2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation: Executive summary



# Section 1: introduction
During the past three decades, catheter and surgical ablation of atrial fibrillation (AF) have evolved from investigational procedures to their current role as effective treatment options for patients with AF. Surgical ablation of AF, using either standard, minimally invasive, or hybrid techniques, is available in most major hospitals throughout the world. Catheter ablation of AF is even more widely available, and is now the most commonly performed catheter ablation procedure.
In 2007, an initial Consensus Statement on Catheter and Surgical AF Ablation was developed as a joint effort of the Heart Rhythm Society (HRS), the European Heart Rhythm Association (EHRA), and the European Cardiac Arrhythmia Society (ECAS). [bib_ref] HRS/EHRA/ECAS expert Consensus Statement on catheter and surgical ablation of atrial fibrillation:..., Calkins [/bib_ref] The 2007 document was also developed in collaboration with the Society of Thoracic Surgeons (STS) and the American College of Cardiology (ACC). This Consensus Statement on Catheter and Surgical AF Ablation was rewritten in 2012 to reflect the many advances in AF ablation that had occurred in the interim. [bib_ref] HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation:..., Calkins [/bib_ref] The rate of advancement in the tools, techniques, and outcomes of AF ablation continue to increase as enormous research efforts are focused on the mechanisms, outcomes, and treatment of AF. For this reason, the HRS initiated an effort to rewrite and update this Consensus Statement. Reflecting both the worldwide importance of AF, as well as the worldwide performance of AF ablation, this document is the result of a joint partnership between the HRS, EHRA, ECAS, the Asia Pacific Heart Rhythm Society (APHRS), and the Latin American Society of Cardiac Stimulation and Electrophysiology (Sociedad Latinoamericana de Estimulacion Cardiaca y Electrofisiologia . The purpose of this 2017 Consensus Statement is to provide a state-of-the-art review of the field of catheter and surgical ablation of AF and to report the findings of a writing group, convened by these five international societies. The writing group is charged with defining the indications, techniques, and outcomes of AF ablation procedures. Included within this document are recommendations pertinent to the design of clinical trials in the field of AF ablation and the reporting of outcomes, including definitions relevant to this topic.
The writing group is composed of 60 experts representing 11 organizations: HRS, EHRA, ECAS, APHRS, SOLAECE, STS, ACC, American Heart Association (AHA), Canadian Heart Rhythm Society (CHRS), Japanese Heart Rhythm Society (JHRS), and Brazilian Society of Cardiac Arrhythmias (Sociedade Brasileira de Arritmias Cardiacas . All the members of the writing group, as well as peer reviewers of the document, have provided disclosure Atrial fibrillation definitions

## Af episode
An AF episode is defined as AF that is documented by ECG monitoring or intracardiac electrogram monitoring and has a duration of at least 30 seconds, or if less than 30 seconds, is present throughout the ECG monitoring tracing. The presence of subsequent episodes of AF requires that sinus rhythm be documented by ECG monitoring between AF episodes.
Chronic AF Chronic AF has variable definitions and should not be used to describe populations of AF patients undergoing AF ablation.
Early persistent AF Early persistent AF is defined as AF that is sustained beyond 7 days but is less than 3 months in duration.
Lone AF Lone AF is a historical descriptor that is potentially confusing and should not be used to describe populations of patients with AF undergoing AF ablation.
statements for all relationships that might be perceived as real or potential conflicts of interest. All author and peer reviewer disclosure information is provided in Appendix A and Appendix B.
In writing a consensus document, it is recognized that consensus does not mean that there was complete agreement among all the writing group members. Surveys of the entire writing group were used to identify areas of consensus concerning performance of AF ablation procedures and to develop recommendations concerning the indications for catheter and surgical AF ablation. These recommendations were systematically balloted by the 60 writing group members and were approved by a minimum of 80% of these members. The recommendations were also subject to a 1-month public comment period. Each partnering and collaborating organization then officially reviewed, commented on, edited, and endorsed the final document and recommendations.
The grading system for indication of class of evidence level was adapted based on that used by the ACC and the AHA. [bib_ref] The evolution and future of ACC/AHA clinical practice guidelines: a 30-year journey:..., Jacobs [/bib_ref] [bib_ref] Evolution of the ACC/AHA clinical practice guidelines in perspective: guiding the guidelines, Anderson [/bib_ref] It is important to state, however, that this document is not a guideline. The indications for catheter and surgical ablation of AF, as well as recommendations for procedure performance, are presented with a Class and Level of Evidence (LOE) to be consistent with what the reader is familiar with seeing in guideline statements. A Class I recommendation means that the benefits of the AF ablation procedure markedly exceed the risks, and that AF ablation should be performed; a Class IIa recommendation means that the benefits of an AF ablation procedure exceed the risks, and that it is Guidelines reasonable to perform AF ablation; a Class IIb recommendation means that the benefit of AF ablation is greater or equal to the risks, and that AF ablation may be considered; and a Class III recommendation means that AF ablation is of no proven benefit and is not recommended.
The writing group reviewed and ranked evidence supporting current recommendations with the weight of evidence ranked as Level A if the data were derived from high-quality evidence from more than one randomized clinical trial, meta-analyses of high-quality randomized clinical trials, or one or more randomized clinical trials corroborated by high-quality registry studies. The writing group ranked available evidence as Level B-R when there was moderatequality evidence from one or more randomized clinical trials, or meta-analyses of moderate-quality randomized clinical trials. Level B-NR was used to denote moderate-quality evidence from one or more well-designed, well-executed nonrandomized studies, observational studies, or registry studies. This designation was also used to denote moderate-quality evidence from meta-analyses of such studies. Evidence was ranked as Level C-LD when the primary source of the recommendation was randomized or nonrandomized observational or registry studies with limitations of design or execution, meta-analyses of such studies, or physiological or mechanistic studies of human subjects. Level C-EO was defined as expert opinion based on the clinical experience of the writing group.
Despite a large number of authors, the participation of several societies and professional organizations, and the attempts of the group to reflect the current knowledge in the field adequately, this document is not intended as a guideline. Rather, the group would like to refer to the current guidelines on AF management for the purpose of guiding overall AF management strategies. [bib_ref] AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report..., January [/bib_ref] [bib_ref] ESC guidelines for the management of atrial fibrillation developed in collaboration with..., Kirchhof [/bib_ref] This consensus document is specifically focused on catheter and surgical ablation of AF, and summarizes the opinion of the writing group members based on an extensive literature review as well as their own experience. It is directed to all health care professionals who are involved in the care of patients with AF, particularly those who are caring for patients who are undergoing, or are being considered for, catheter or surgical ablation procedures for AF, and those involved in research in the field of AF ablation. This The extension of muscular fibers onto the PVs can be appreciated. Shown in yellow are the five major left atrial autonomic ganglionic plexi (GP) and axons (superior left GP, inferior left GP, anterior right GP, inferior right GP, and ligament of Marshall). Shown in blue is the coronary sinus, which is enveloped by muscular fibers that have connections to the atria. Also shown in blue is the vein and ligament of Marshall, which travels from the coronary sinus to the region between the left superior PV and the left atrial appendage. (B) The large and small reentrant wavelets that play a role in initiating and sustaining AF. (C) The common locations of PV (red) and also the common sites of origin of non-PV triggers (shown in green). (D) Composite of the anatomic and arrhythmic mechanisms of AF. Adapted with permission from Calkins et al. Heart Rhythm 2012; 9:632-696.e21. [bib_ref] HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation:..., Calkins [/bib_ref] statement is not intended to recommend or promote catheter or surgical ablation of AF. Rather, the ultimate judgment regarding care of a particular patient must be made by the health care provider and the patient in light of all the circumstances presented by that patient.
The main objective of this document is to improve patient care by providing a foundation of knowledge for those involved with catheter ablation of AF. A second major objective is to provide recommendations for designing clinical trials and reporting outcomes of clinical trials of AF ablation. It is recognized that this field continues to evolve rapidly. As this document was being prepared, further clinical trials of catheter and surgical ablation of AF were under way.

## Section 2: definitions, mechanisms, and rationale for af ablation
This section of the document provides definitions for use in the diagnosis of AF. This section also provides an in-depth review of the mechanisms of AF and rationale for catheter and surgical AF ablation [fig_ref] Figure 1: Anatomical drawings of the heart relevant to AF ablation [/fig_ref].

## Section 3: modifiable risk factors for af and impact on ablation
Management of patients with AF has traditionally consisted of three main components: (1) anticoagulation for stroke prevention; (2) rate control; and (3) rhythm control. With the emergence of large amounts of data, which have both defined and called attention to the interaction between modifiable risk factors and the development of AF and outcomes of AF management, we believe it is time to include risk factor modification as the fourth pillar of AF management. This section of the document reviews the link between modifiable risk factors and both the development of AF and their impacts on the outcomes of AF ablation. [fig_ref] Table 2: A subset of operators empirically isolates the SVC [/fig_ref] , and summarized in [fig_ref] Figure 7: Indications for catheter ablation of symptomatic atrial fibrillation [/fig_ref] of this document, are the Consensus Indications for Catheter and Surgical Ablation of AF. As outlined in the introduction section of this document, these indications are stratified as Class I, Class IIa, Class IIb, and Class III indications. The evidence supporting these indications is provided, as well as a selection of the key references supporting these levels of Guidelines evidence. In making these recommendations, the writing group considered the body of published literature that has defined the safety and efficacy of catheter and surgical ablation of AF. Also considered in these recommendations is the personal lifetime experience in the field of each of the writing group members. Both the number of clinical trials and the quality of these trials were considered. In considering the class of indications recommended by this writing group, it is important to keep several points in mind. First, these classes of indications only define the indications for catheter and surgical ablation of AF when performed by an electrophysiologist or a surgeon who has received appropriate training and/or who has a certain level of experience and is performing the procedure in an experienced center (Section 11). Catheter and surgical ablation of AF are highly complex procedures, and a careful assessment of the benefit and risk must be considered for each patient. Second, these indications stratify patients based only on the type of AF and whether the procedure is being performed prior to or following a trial of one or more Class I or III antiarrhythmic medications. This document for the first time includes indications for catheter ablation of select asymptomatic patients. As detailed in Section 9, there are many other additional clinical and imaging-based variables that can be used to further define the efficacy and risk of ablation in a given patient. Some of the variables that can be used to define patients in whom a lower success rate or a higher complication rate can be expected include the presence of concomitant heart disease, obesity, sleep apnea, left atrial (LA) size, patient age and frailty, as well as the duration of time the patient has been in continuous AF. Each of these variables needs to be considered when discussing the risks and benefits of AF ablation with a particular patient. In the presence of substantial risk or anticipated difficulty of ablation, it could be more appropriate to use additional antiarrhythmic drug (AAD) options, even if the patient on face value might present with a Class I or IIa indication for ablation. Third, it is The circumferential ablation lesions that are created in a circumferential fashion around the right and the left PVs. The primary endpoint of this ablation strategy is the electrical isolation of the PV musculature. (B) Some of the most common sites of linear ablation lesions. These include a "roof line" connecting the lesions encircling the left and/or right PVs, a "mitral isthmus" line connecting the mitral valve and the lesion encircling the left PVs at the end of the left inferior PV, and an anterior linear lesion connecting either the "roof line" or the left or right circumferential lesion to the mitral annulus anteriorly. A linear lesion created at the cavotricuspid isthmus is also shown. This lesion is generally placed in patients who have experienced cavotricuspid isthmus-dependent atrial flutter clinically or have it induced during EP testing. (C) Similar to 6B, but also shows additional linear ablation lesions between the superior and inferior PVs resulting in a figure of eight lesion sets as well as a posterior inferior line allowing for electrical isolation of the posterior left atrial wall. An encircling lesion of the superior vena cava (SVC) directed at electrical isolation of the SVC is also shown. SVC isolation is performed if focal firing from the SVC can be demonstrated. Long-standing persistent: Surgical ablation is reasonable.

## Section 4: indications

## Shown in
IIa B-NR [bib_ref] A new epicardial lesion set for minimal access left atrial maze: the..., Edgerton [/bib_ref] [bib_ref] Totally thorascopic surgical ablation of persistent AF and long-standing persistent atrial fibrillation..., Edgerton [/bib_ref] [bib_ref] Linear left atrial lesions in minimally invasive surgical ablation of persistent atrial..., Lockwood [/bib_ref] [bib_ref] Atrial fibrillation ablation in patients undergoing aortic valve replacement, Malaisrie [/bib_ref] [bib_ref] Assessment of results of surgical treatment for persistent atrial fibrillation during coronary..., Cherniavsky [/bib_ref] [bib_ref] Impact of concomitant surgical atrial fibrillation ablation in patients undergoing aortic valve..., Yoo [/bib_ref] Continued Guidelines important to consider patient preference and values. Some patients are reluctant to consider a major procedure or surgery and have a strong preference for a pharmacological approach. In these patients, trials of antiarrhythmic agents including amiodarone might be preferred to catheter ablation. On the other hand, some patients prefer a nonpharmacological approach. Fourth, it is important to recognize that some patients early in the course of their AF journey might have only infrequent episodes for many years and/or could have AF that is responsive to well-tolerated AAD therapy. And finally, it is important to bear in mind that a decision to perform catheter or surgical AF ablation should only be made after a patient carefully considers the risks, benefits, and alternatives to the procedure.

## Section 5: strategies, techniques, and endpoints
The writing group recommendations for techniques to be used for ablation of persistent and long-standing persistent AF [fig_ref] Table 3: Atrial fibrillation ablation [/fig_ref] , adjunctive ablation strategies, nonablative strategies to improve outcomes of AF ablation, and endpoints for ablation of paroxysmal, persistent, and long-standing persistent AF are covered in this section. A schematic overview of common lesion sets created during an AF ablation procedure is shown in [fig_ref] Figure 6: Schematic of common lesion sets employed in AF ablation [/fig_ref].

## Section 6: technology and tools
This section of the consensus statement provides an update on many of the technologies and tools that are employed for AF ablation procedures. It is important to recognize that this is not a comprehensive listing and that new technologies, tools, and approaches are being developed. It is also important to recognize that radiofrequency (RF) energy is the dominant energy source available for ablation of typical and atypical atrial flutter (AFL). Although cryoablation is a commonly employed tool for AF ablation, it is not well suited for ablation of typical or atypical AFL. Other energy sources and tools are available in some parts of the world and/or are in various stages of development and/or clinical investigation. Shown in [fig_ref] Figure 9: Schematic drawing showing catheter ablation of atrial fibrillation using either RF energy... [/fig_ref] are schematic drawings of AF ablation using point-by-point RF energy [fig_ref] Figure 9: Schematic drawing showing catheter ablation of atrial fibrillation using either RF energy... [/fig_ref] and AF ablation using the cryoballoon (CB) system [fig_ref] Figure 9: Schematic drawing showing catheter ablation of atrial fibrillation using either RF energy... [/fig_ref]. A decision to perform AF ablation in an asymptomatic patient requires additional discussion with the patient because the potential benefits of the procedure for the patient without symptoms are uncertain.

## Section 7: technical aspects of ablation to maximize safety and anticoagulation
Anticoagulation strategies pre-, during, and postcatheter ablation of AF ; signs and symptoms of complications that can occur within the first several months following ablation ; anesthesia or sedation during ablation; and approaches to minimize risk of an atrial esophageal fistula are discussed in this section.

## Section 8: follow-up considerations
AF ablation is an invasive procedure that entails risks, most of which are present during the acute procedural period. However, complications can also occur in the weeks or months following ablation. Recognizing common symptoms after AF ablation and distinguishing those that require urgent evaluation and referral to an electrophysiologist is an important part of follow-up after AF ablation. The success of AF ablation is based in large part on freedom from AF If a reproducible focal trigger that initiates AF is identified outside the PV ostia at the time of an AF ablation procedure, ablation of the focal trigger should be considered.
IIa C-LD [bib_ref] Catheter ablation of atrial fibrillation originating from the non-pulmonary vein foci, Chen [/bib_ref] [bib_ref] Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary..., Haissaguerre [/bib_ref] [bib_ref] Predictors of non-pulmonary vein ectopic beats initiating paroxysmal atrial fibrillation: implication for..., Lee [/bib_ref] [bib_ref] Alterations of heart rate variability after radiofrequency catheter ablation of focal atrial..., Hsieh [/bib_ref] [bib_ref] Nonpulmonary vein foci: do they exist?, Shah [/bib_ref] [bib_ref] Provocability of atrial fibrillation triggers during pulmonary vein isolation in patients with..., Lin [/bib_ref] [bib_ref] Left atrial appendage: an underrecognized trigger site of atrial fibrillation, Biase [/bib_ref] [bib_ref] Prevalence and distribution of focal triggers in persistent and long-standing persistent atrial..., Santangeli [/bib_ref] [bib_ref] Catheter ablation of paroxysmal atrial fibrillation initiated by nonpulmonary vein ectopy, Lin [/bib_ref] [bib_ref] Percutaneous alternative to the Maze procedure for the treatment of persistent or..., Lee [/bib_ref] [bib_ref] Importance of non-pulmonary vein triggers ablation to achieve long-term freedom from paroxysmal..., Zhao [/bib_ref] [bib_ref] Randomized ablation strategies for the treatment of persistent atrial fibrillation: RASTA study, Dixit [/bib_ref] When performing AF ablation with a force-sensing RF ablation catheter, a minimal targeted contact force of 5 to 10 grams is reasonable.
IIa C-LD [bib_ref] Paroxysmal AF catheter ablation with a contact force sensing catheter: results of..., Natale [/bib_ref] [bib_ref] Comparison of antiarrhythmic drug therapy and radiofrequency catheter ablation in patients with..., Wilber [/bib_ref] [bib_ref] Pulmonary vein isolation using "contact force" ablation: the effect on dormant conduction..., Andrade [/bib_ref] [bib_ref] Electrical reconnection after pulmonary vein isolation is contingent on contact force during..., Neuzil [/bib_ref] [bib_ref] Novel contact force sensor incorporated in irrigated radiofrequency ablation catheter predicts lesion..., Yokoyama [/bib_ref] [bib_ref] Relationship between catheter contact force and radiofrequency lesion size and incidence of..., Ikeda [/bib_ref] [bib_ref] Locations of high contact force during left atrial mapping in atrial fibrillation..., Nakagawa [/bib_ref] [bib_ref] Predictive value of impedance changes for real-time contact force measurements during catheter..., Kumar [/bib_ref] [bib_ref] Prospective characterization of catheter-tissue contact force at different anatomic sites during antral..., Kumar [/bib_ref] [bib_ref] The relationship between contact force and clinical outcome during radiofrequency catheter ablation..., Reddy [/bib_ref] [bib_ref] Contact force sensing technology identifies sites of inadequate contact and reduces acute..., Haldar [/bib_ref] [bib_ref] Assessment of catheter tip contact force resulting in cardiac perforation in swine..., Perna [/bib_ref] [bib_ref] Comparison of lesion formation between contact force-guided and non-guided circumferential pulmonary vein..., Kimura [/bib_ref] [bib_ref] Quantitative magnetic resonance imaging analysis of the relationship between contact force and..., Sohns [/bib_ref] [bib_ref] Clinical impact of an open-irrigated radiofrequency catheter with direct force measurement on..., Martinek [/bib_ref] [bib_ref] Real-time contact force sensing for pulmonary vein isolation in the setting of..., Marijon [/bib_ref] [bib_ref] Optimizing radiofrequency ablation of paroxysmal and persistent atrial fibrillation by direct catheter..., Sigmund [/bib_ref] [bib_ref] Randomized trial comparing pulmonary vein isolation using the SmartTouch catheter with or..., Ullah [/bib_ref] [bib_ref] Impact of real-time contact force and impedance measurement in pulmonary vein isolation..., Wakili [/bib_ref] Posterior wall isolation might be considered for initial or repeat ablation of persistent or long-standing persistent AF.
IIb C-LD [bib_ref] Left atrial posterior wall isolation does not improve the outcome of circumferential..., Tamborero [/bib_ref] [bib_ref] A new approach for complete isolation of the posterior left atrium including..., Kumagai [/bib_ref] [bib_ref] Long-term effects of box isolation on sympathovagal balance in atrial fibrillation, Yamaguchi [/bib_ref] [bib_ref] Catheter ablation of atrial fibrillation. State of the Art, Kumagai [/bib_ref] [bib_ref] Does isolation of the left atrial posterior wall improve clinical outcomes after..., Kim [/bib_ref] [bib_ref] Left atrial posterior wall isolation reduces the recurrence of atrial fibrillation: a..., He [/bib_ref] [bib_ref] Left atrial appendage isolation in patients with long-standing persistent AF undergoing catheter..., Biase [/bib_ref] [bib_ref] Ablation versus amiodarone for treatment of persistent atrial fibrillation in patients with..., Biase [/bib_ref] Administration of high-dose isoproterenol to screen for and then ablate non-PV triggers may be considered during initial or repeat AF ablation procedures in patients with paroxysmal, persistent, or long-standing persistent AF.
IIb C-LD [bib_ref] Catheter ablation of atrial fibrillation originating from the non-pulmonary vein foci, Chen [/bib_ref] [bib_ref] Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary..., Haissaguerre [/bib_ref] [bib_ref] Predictors of non-pulmonary vein ectopic beats initiating paroxysmal atrial fibrillation: implication for..., Lee [/bib_ref] [bib_ref] Alterations of heart rate variability after radiofrequency catheter ablation of focal atrial..., Hsieh [/bib_ref] [bib_ref] Nonpulmonary vein foci: do they exist?, Shah [/bib_ref] [bib_ref] Provocability of atrial fibrillation triggers during pulmonary vein isolation in patients with..., Lin [/bib_ref] [bib_ref] Left atrial appendage: an underrecognized trigger site of atrial fibrillation, Biase [/bib_ref] [bib_ref] Prevalence and distribution of focal triggers in persistent and long-standing persistent atrial..., Santangeli [/bib_ref] [bib_ref] Catheter ablation of paroxysmal atrial fibrillation initiated by nonpulmonary vein ectopy, Lin [/bib_ref] [bib_ref] Percutaneous alternative to the Maze procedure for the treatment of persistent or..., Lee [/bib_ref] [bib_ref] Importance of non-pulmonary vein triggers ablation to achieve long-term freedom from paroxysmal..., Zhao [/bib_ref] [bib_ref] Randomized ablation strategies for the treatment of persistent atrial fibrillation: RASTA study, Dixit [/bib_ref] DF-based ablation strategy is of unknown usefulness for AF ablation.
IIb C-LD [bib_ref] Chronic rapid atrial pacing. Structural, functional, and electrophysiological characteristics of a new..., Morillo [/bib_ref] [bib_ref] Atrial activation during chronic atrial fibrillation in patients with isolated mitral valve..., Harada [/bib_ref] [bib_ref] Spatial and temporal organization during cardiac fibrillation, Gray [/bib_ref] [bib_ref] Spatially distributed dominant excitation frequencies reveal hidden organization in atrial fibrillation in..., Berenfeld [/bib_ref] [bib_ref] Left-to-right gradient of atrial frequencies during acute atrial fibrillation in the isolated..., Mansour [/bib_ref] [bib_ref] Presence of left-to-right atrial frequency gradient in paroxysmal but not persistent atrial..., Lazar [/bib_ref] [bib_ref] Real-time dominant frequency mapping and ablation of dominant frequency sites in atrial..., Atienza [/bib_ref] [bib_ref] Comparison of radiofrequency catheter ablation of drivers and circumferential pulmonary vein isolation..., Atienza [/bib_ref] The usefulness of creating linear ablation lesions in the right or left atrium as an initial or repeat ablation strategy for persistent or long-standing persistent AF is not well established.
IIb B-NR [bib_ref] Approaches to catheter ablation for persistent atrial fibrillation, Verma [/bib_ref] [bib_ref] Five-year outcome of catheter ablation of persistent atrial fibrillation using termination of..., Scherr [/bib_ref] [bib_ref] Randomized study comparing combined pulmonary vein-left atrial junction disconnection and cavotricuspid isthmus..., Wazni [/bib_ref] [bib_ref] Circumferential pulmonary vein ablation with additional linear ablation results in an increased..., Sawhney [/bib_ref] [bib_ref] Atrial tachycardia after circumferential pulmonary vein ablation of atrial fibrillation: mechanistic insights,..., Chae [/bib_ref] [bib_ref] Characterization of reentrant circuits in left atrial macroreentrant tachycardia: critical isthmus block..., Ouyang [/bib_ref] [bib_ref] Peri-mitral atrial flutter in patients with atrial fibrillation ablation, Matsuo [/bib_ref] [bib_ref] The modified anterior line: an alternative linear lesion in perimitral flutter, Tzeis [/bib_ref] [bib_ref] Pulmonary vein isolation versus defragmentation: the CHASE-AF clinical trial, Vogler [/bib_ref] [bib_ref] Catheter ablation of long-lasting persistent atrial fibrillation: clinical outcome and mechanisms of..., Haissaguerre [/bib_ref] [bib_ref] A new approach for catheter ablation of atrial fibrillation: mapping of the..., Nademanee [/bib_ref] [bib_ref] Long-term follow-up of persistent atrial fibrillation ablation using termination as a procedural..., O&apos;neill [/bib_ref] [bib_ref] Predicting factors for atrial fibrillation acute termination during catheter ablation procedures: implications..., Lo [/bib_ref] [bib_ref] Linear ablation following pulmonary vein isolation in patients with atrial fibrillation: a..., Zhang [/bib_ref] [bib_ref] Linear ablation in addition to circumferential pulmonary vein isolation (Dallas lesion set)..., Kim [/bib_ref] [bib_ref] Biatrial linear ablation in sustained nonpermanent AF: results of the substrate modification..., Wynn [/bib_ref] The usefulness of linear ablation lesions in the absence of macroreentrant atrial flutter is not well established.
IIb C-LD [bib_ref] Approaches to catheter ablation for persistent atrial fibrillation, Verma [/bib_ref] [bib_ref] Five-year outcome of catheter ablation of persistent atrial fibrillation using termination of..., Scherr [/bib_ref] [bib_ref] Randomized study comparing combined pulmonary vein-left atrial junction disconnection and cavotricuspid isthmus..., Wazni [/bib_ref] [bib_ref] Circumferential pulmonary vein ablation with additional linear ablation results in an increased..., Sawhney [/bib_ref] [bib_ref] Atrial tachycardia after circumferential pulmonary vein ablation of atrial fibrillation: mechanistic insights,..., Chae [/bib_ref] [bib_ref] Characterization of reentrant circuits in left atrial macroreentrant tachycardia: critical isthmus block..., Ouyang [/bib_ref] [bib_ref] Peri-mitral atrial flutter in patients with atrial fibrillation ablation, Matsuo [/bib_ref] [bib_ref] The modified anterior line: an alternative linear lesion in perimitral flutter, Tzeis [/bib_ref] [bib_ref] Pulmonary vein isolation versus defragmentation: the CHASE-AF clinical trial, Vogler [/bib_ref] [bib_ref] Catheter ablation of long-lasting persistent atrial fibrillation: clinical outcome and mechanisms of..., Haissaguerre [/bib_ref] [bib_ref] A new approach for catheter ablation of atrial fibrillation: mapping of the..., Nademanee [/bib_ref] [bib_ref] Long-term follow-up of persistent atrial fibrillation ablation using termination as a procedural..., O&apos;neill [/bib_ref] [bib_ref] Predicting factors for atrial fibrillation acute termination during catheter ablation procedures: implications..., Lo [/bib_ref] [bib_ref] Linear ablation following pulmonary vein isolation in patients with atrial fibrillation: a..., Zhang [/bib_ref] [bib_ref] Linear ablation in addition to circumferential pulmonary vein isolation (Dallas lesion set)..., Kim [/bib_ref] [bib_ref] Biatrial linear ablation in sustained nonpermanent AF: results of the substrate modification..., Wynn [/bib_ref] The usefulness of mapping and ablation of areas of abnormal myocardial tissue identified with voltage mapping or MRI as an initial or repeat ablation strategy for persistent or long-standing persistent AF is not well established.
IIb B-R [bib_ref] A new approach for complete isolation of the posterior left atrium including..., Kumagai [/bib_ref] [bib_ref] Box Isolation of Fibrotic Areas (BIFA): a patient-tailored substrate modification approach for..., Kottkamp [/bib_ref] [bib_ref] Catheter ablation of atrial fibrillation: how to modify the substrate?, Kottkamp [/bib_ref] [bib_ref] Tailored atrial substrate modification based on low-voltage areas in catheter ablation of..., Rolf [/bib_ref] [bib_ref] Proven isolation of the pulmonary vein antrum with or without left atrial..., Bai [/bib_ref] [bib_ref] Impact of voltage mapping to guide whether to perform ablation of the..., Cutler [/bib_ref] [bib_ref] Catheter ablation of nonparoxysmal atrial fibrillation using electrophysiologically guided substrate modification during..., Yang [/bib_ref] [bib_ref] Pre-existent left atrial scarring in patients undergoing pulmonary vein antrum isolation: an..., Verma [/bib_ref] [bib_ref] Contact electroanatomic mapping derived voltage criteria for characterizing left atrial scar in..., Kapa [/bib_ref] [bib_ref] Detection and quantification of left atrial structural remodeling with delayed-enhancement magnetic resonance..., Oakes [/bib_ref] [bib_ref] Atrial fibrillation ablation outcome is predicted by left atrial remodeling on MRI, Mcgann [/bib_ref] The usefulness of ablation of complex fractionated atrial electrograms as an initial or repeat ablation strategy for persistent and long-standing persistent AF is not well established.
IIb B-R [bib_ref] Approaches to catheter ablation for persistent atrial fibrillation, Verma [/bib_ref] [bib_ref] Five-year outcome of catheter ablation of persistent atrial fibrillation using termination of..., Scherr [/bib_ref] [bib_ref] Catheter ablation of long-lasting persistent atrial fibrillation: clinical outcome and mechanisms of..., Haissaguerre [/bib_ref] [bib_ref] A new approach for catheter ablation of atrial fibrillation: mapping of the..., Nademanee [/bib_ref] [bib_ref] Long-term follow-up of persistent atrial fibrillation ablation using termination as a procedural..., O&apos;neill [/bib_ref] [bib_ref] Current ablation techniques for persistent atrial fibrillation: results of the European Heart..., Dagres [/bib_ref] [bib_ref] Clinical outcomes of catheter substrate ablation for highrisk patients with atrial fibrillation, Nademanee [/bib_ref] [bib_ref] Localized sources maintaining atrial fibrillation organized by prior ablation, Haissaguerre [/bib_ref] [bib_ref] Catheter ablation of long-lasting persistent atrial fibrillation: critical structures for termination, Haissaguerre [/bib_ref] [bib_ref] Characterization of electrograms associated with termination of chronic atrial fibrillation by catheter..., Takahashi [/bib_ref] [bib_ref] Intraprocedural use of ibutilide to organize and guide ablation of complex fractionated..., Singh [/bib_ref] [bib_ref] Classifying fractionated electrograms in human atrial fibrillation using monophasic action potentials and..., Narayan [/bib_ref] [bib_ref] Selective CFAE targeting for atrial fibrillation study (SELECT AF): clinical rationale, design,..., Verma [/bib_ref] [bib_ref] Mechanistic approaches to detect, target, and ablate the drivers of atrial fibrillation, Quintanilla [/bib_ref] The usefulness of ablation of rotational activity as an initial or repeat ablation strategy for persistent and long-standing persistent AF is not well established.
IIb B-NR The usefulness of ablation of autonomic ganglia as an initial or repeat ablation strategy for paroxysmal, persistent, and long-standing persistent AF is not well established. It is reasonable to consider a patient's BMI when discussing the risks, benefits, and outcomes of AF ablation with a patient being evaluated for an AF ablation procedure.

## Iib
IIa B-R It is reasonable to screen for signs and symptoms of sleep apnea when evaluating a patient for an AF ablation pro- The usefulness of discontinuation of antiarrhythmic drug therapy prior to AF ablation in an effort to improve longterm outcomes is unclear.
IIb C-LD [bib_ref] Reversal of electrical remodeling after cardioversion of persistent atrial fibrillation, Raitt [/bib_ref] [bib_ref] Reverse electrical remodeling of the atria post cardioversion in patients who remain..., Chalfoun [/bib_ref] [bib_ref] Effect of restoration of sinus rhythm by extensive antiarrhythmic drugs in predicting..., Igarashi [/bib_ref] [bib_ref] Improved outcome following restoration of sinus rhythm prior to catheter ablation of..., Rivard [/bib_ref] [bib_ref] Effect of periprocedural amiodarone on procedure outcome in patients with long-standing persistent..., Mohanty [/bib_ref] The usefulness of initiation or continuation of antiarrhythmic drug therapy during the postablation healing phase in an effort to improve long-term outcomes is unclear.
IIb C-LD [bib_ref] Reversal of electrical remodeling after cardioversion of persistent atrial fibrillation, Raitt [/bib_ref] [bib_ref] Reverse electrical remodeling of the atria post cardioversion in patients who remain..., Chalfoun [/bib_ref] [bib_ref] Effect of restoration of sinus rhythm by extensive antiarrhythmic drugs in predicting..., Igarashi [/bib_ref] [bib_ref] Improved outcome following restoration of sinus rhythm prior to catheter ablation of..., Rivard [/bib_ref] [bib_ref] Effect of periprocedural amiodarone on procedure outcome in patients with long-standing persistent..., Mohanty [/bib_ref] Strategies to reduce the risks of AF Performance of a TEE in patients who present for ablation in sinus rhythm and who have not been anticoagulated prior to catheter ablation is reasonable.
[formula] IIa C-EO 5,6 [/formula]
Use of intracardiac echocardiography to screen for atrial thrombi in patients who cannot undergo TEE may be considered.
IIb C-EO [bib_ref] Left atrial thrombus associated with ablation for atrial fibrillation: identification with intracardiac..., Ren [/bib_ref] [bib_ref] A prospective comparison of cardiac imaging using intracardiac echocardiography with transesophageal echocardiography..., Saksena [/bib_ref] [bib_ref] Intracardiac echocardiography for detection of thrombus in the left atrial appendage: comparison..., Baran [/bib_ref] [bib_ref] Intracardiac echocardiographic diagnosis of thrombus formation in the left atrial appendage: a..., Ren [/bib_ref] [bib_ref] Comparison of intracardiac echocardiography and transesophageal echocardiography for imaging of the right..., Anter [/bib_ref] [bib_ref] Detection of left atrial thrombus by intracardiac echocardiography in patients undergoing ablation..., Sriram [/bib_ref] During ablation Heparin should be administered prior to or immediately following transseptal puncture during AF catheter ablation procedures and adjusted to achieve and maintain an ACT of at least 300 seconds.
[formula] I B-NR 369,380-382,387-393 [/formula]
Administration of protamine following AF catheter ablation to reverse heparin is reasonable.
IIa B-NR [bib_ref] Incidence and outcomes of protamine reactions in patients undergoing catheter ablation of..., Chilukuri [/bib_ref] Postablation
In patients who are not therapeutically anticoagulated prior to catheter ablation of AF and in whom warfarin will be used for anticoagulation postablation, low molecular weight heparin or intravenous heparin should be used as a bridge for initiation of systemic anticoagulation with warfarin following AF ablation.*

## I c-eo
Systemic anticoagulation with warfarin* or a NOAC is recommended for at least 2 months postcatheter ablation of AF.
[formula] I C-EO 1,2 [/formula]
Adherence to AF anticoagulation guidelines is recommended for patients who have undergone an AF ablation procedure, regardless of the apparent success or failure of the procedure.
[formula] I C-EO 5,6 [/formula]
Decisions regarding continuation of systemic anticoagulation more than 2 months post ablation should be based on the patient's stroke risk profile and not on the perceived success or failure of the ablation procedure.
[formula] I C-EO 5,6 [/formula]
In patients who have not been anticoagulated prior to catheter ablation of AF or in whom anticoagulation with a NOAC or warfarin has been interrupted prior to ablation, administration of a NOAC 3 to 5 hours after achievement of hemostasis is reasonable postablation. Asymptomatic cerebral embolism is defined as an occlusion of a blood vessel in the brain due to an embolus that does not result in any acute clinical symptoms. Silent cerebral embolism is generally detected using a diffusion weighted MRI.
Atrioesophageal fistula An atrioesophageal fistula is defined as a connection between the atrium and the lumen of the esophagus. Evidence supporting this diagnosis includes documentation of esophageal erosion combined with evidence of a fistulous connection to the atrium, such as air emboli, an embolic event, or direct observation at the time of surgical repair. A CT scan or MRI scan is the most common method of documentation of an atrioesophageal fistula.

## Bleeding
Bleeding is defined as a major complication of AF ablation if it requires and/or is treated with transfusion or results in a 20% or greater fall in hematocrit.
Bleeding following cardiac surgery Excessive bleeding following a surgical AF ablation procedure is defined as bleeding requiring reoperation or > _ 2 units of PRBC transfusion within any 24 hours of the first 7 days following the index procedure.

## Cardiac perforation
We recommend that cardiac perforation be defined together with cardiac tamponade. See "Cardiac tamponade/ perforation."

## Cardiac tamponade
We recommend that cardiac tamponade be defined together with cardiac perforation. See "Cardiac tamponade/ perforation."
Cardiac tamponade/ perforation Cardiac tamponade/perforation is defined as the development of a significant pericardial effusion during or within 30 days of undergoing an AF ablation procedure. A significant pericardial effusion is one that results in hemodynamic compromise, requires elective or urgent pericardiocentesis, or results in a 1-cm or more pericardial effusion as documented by echocardiography. Cardiac tamponade/perforation should also be classified as "early" or "late" depending on whether it is diagnosed during or following initial discharge from the hospital. Deep sternal wound infection/mediastinitis following cardiac surgery
Deep sternal wound infection/mediastinitis following cardiac surgery requires one of the following: (1) an organism isolated from culture of mediastinal tissue or fluid; (2) evidence of mediastinitis observed during surgery; (3) one of the following conditions: chest pain, sternal instability, or fever (>38 C), in combination with either purulent discharge from the mediastinum or an organism isolated from blood culture or culture of mediastinal drainage.

## Esophageal injury
Esophageal injury is defined as an erosion, ulceration, or perforation of the esophagus. The method of screening for esophageal injury should be specified. Esophageal injury can be a mild complication (erosion or ulceration) or a major complication (perforation).
Gastric motility/pyloric spasm disorders Gastric motility/pyloric spasm disorder should be considered a major complication of AF ablation when it prolongs or requires hospitalization, requires intervention, or results in late disability, such as weight loss, early satiety, diarrhea, or GI disturbance.

## Major complication
A major complication is a complication that results in permanent injury or death, requires intervention for treatment, or prolongs or requires hospitalization for more than 48 hours. Because early recurrences of AF/AFL/AT are to be expected following AF ablation, recurrent AF/AFL/AT within 3 months that requires or prolongs a patient's hospitalization should not be considered to be a major complication of AF ablation.

## Mediastinitis
Mediastinitis is defined as inflammation of the mediastinum. Diagnosis requires one of the following: (1) an organism isolated from culture of mediastinal tissue or fluid; (2) evidence of mediastinitis observed during surgery; (3) one of the following conditions: chest pain, sternal instability, or fever (>38 C), in combination with either purulent discharge from the mediastinum or an organism isolated from blood culture or culture of mediastinal drainage. Myocardial infarction in the context of AF ablation
The universal definition of myocardial infarction 395 cannot be applied in the context of catheter or surgical AF ablation procedures because it relies heavily on cardiac biomarkers (troponin and CPK), which are anticipated to increase in all patients who undergo AF ablation as a result of the ablation of myocardial tissue. Similarly, chest pain and other cardiac symptoms are difficult to interpret in the context of AF ablation both because of the required sedation and anesthesia and also because most patients experience chest pain following the procedure as a result of the associated pericarditis that occurs following catheter ablation. We therefore propose that a myocardial infarction, in the context of catheter or surgical ablation, be defined as the presence of any one of the following criteria: (1) detection of ECG changes indicative of new ischemia (new ST-T wave changes or new LBBB) that persist for more than 1 hour;
(2) development of new pathological Q waves on an ECG; (3) imaging evidence of new loss of viable myocardium or new regional wall motion abnormality.

## Pericarditis
Pericarditis should be considered a major complication following ablation if it results in an effusion that leads to hemodynamic compromise or requires pericardiocentesis, prolongs hospitalization by more than 48 hours, requires hospitalization, or persists for more than 30 days following the ablation procedure.
Phrenic nerve paralysis Phrenic nerve paralysis is defined as absent phrenic nerve function as assessed by a sniff test. A phrenic nerve paralysis is considered to be permanent when it is documented to be present 12 months or longer following ablation.

## Continued
Guidelines recurrence based on ECG monitoring. Arrhythmia monitoring can be performed with the use of noncontinuous or continuous ECG monitoring tools . This section also discusses the important topics of AAD and non-AAD use prior to and following AF ablation, the role of cardioversion, as well as the indications for and timing of repeat AF ablation procedures.

## Section 9: outcomes and efficacy
This section provides a comprehensive review of the outcomes of catheter ablation of AF. [fig_ref] Table 7: Selected clinical trials of catheter ablation of atrial fibrillation and/or for FDA... [/fig_ref] summarizes the main findings of the most important clinical trials in this field. Outcomes of AF ablation in subsets of patients not well represented in these trials are reviewed. Outcomes for specific ablation systems and strategies (CB ablation, rotational activity ablation, and laser balloon ablation) are also reviewed.

## Section 10: complications
Catheter ablation of AF is one of the most complex interventional electrophysiological procedures. AF ablation by its nature involves catheter manipulation and ablation in the delicate thin-walled atria, which are in close proximity to other important organs and structures that can be impacted through collateral damage. It is therefore not surprising that AF ablation is associated with a significant risk of complications, some of which might result in life-long disability and/ or death. This section reviews the complications associated with catheter ablation procedures performed to treat AF. The types and incidence of complications are presented, their mechanisms are explored, and the optimal approach to prevention and treatment is discussed [fig_ref] Figure 8: Indications for surgical ablation of atrial fibrillation [/fig_ref]. Acute procedural success is defined as electrical isolation of all pulmonary veins. A minimal assessment of electrical isolation of the PVs should consist of an assessment of entrance block. If other methods are used to assess PVI, including exit block and/or the use of provocative agents such as adenosine or isoproterenol, they should be prespecified. Furthermore, it is recommended that the wait time used to screen for early recurrence of PV conduction once initial electrical isolation is documented be specified in all prospective clinical trials.
Acute procedural success (not related by pulmonary vein isolation)
Typically, this would apply to substrate ablation performed in addition to PVI for persistent AF. Although some have proposed AF termination as a surrogate for acute procedural success, its relationship to long-term success is controversial. Complete elimination of the additional substrate (localized rotational activation, scar region, non-PV trigger, or other target) and/or demonstration of bidirectional conduction block across a linear ablation lesion would typically be considered the appropriate endpoint.
One-year success* One-year success is defined as freedom from AF/AFL/AT after removal from antiarrhythmic drug therapy as assessed from the end of the 3month blanking period to 12 months following the ablation procedure. Because cavotricuspid isthmus-dependent atrial flutter is easily treated with cavotricuspid isthmus ablation and is not an iatrogenic arrhythmia following a left atrial ablation procedure for AF, it is reasonable for clinical trials to choose to prespecify that occurrence of isthmus-dependent atrial flutter, if confirmed by entrainment maneuvers during electrophysiology testing, should not be considered an ablation failure or primary effectiveness endpoint.

## Alternative one-year success
Although the one-year success definition provided above remains the recommended end point that should be reported in all AF ablation trials, and the endpoint for which the objective performance criteria listed below were developed, the Task Force recognizes that alternative definitions for success can be used if the main goal of therapy in the study is to relieve AF-related symptoms and to improve patient QOL. In particular, it is appropriate for clinical trials to define success as freedom from only symptomatic AF/AFL/AT after removal from antiarrhythmic drug therapy as assessed from the end of the 3-month blanking period to 12 months following the ablation procedure if the main goal of therapy in the study is to relieve AF-related symptoms and to improve patient QOL. However, because symptoms of AF can resolve over time, and because studies have shown that asymptomatic AF represents a greater proportion of all AF postablation than prior to ablation, clinical trials need to continue to report freedom from both symptomatic and asymptomatic AF even if this alternative one year success definition is used as the primary trial endpoint. Clinical/partial success* It is reasonable for clinical trials to define and incorporate one or more secondary definitions of success that can be referred to as "clinical success" or "partial success." If these alternative definitions of success are included, they should be defined prospectively. In prior Consensus Documents the Task Force has proposed that clinical/partial success be defined as a "75% or greater reduction in the number of AF episodes, the duration of AF episodes, or the % time a patient is in AF as assessed with a device capable of measuring AF burden in the presence or absence of previously ineffective antiarrhythmic drug therapy." Because there is no firm scientific basis for selecting the cutoff of 75% rather than a different cutoff, this prior recommendation is provided only as an example of what future clinical trials may choose to use as a definition of clinical/partial success.
Long-term success* Long-term success is defined as freedom from AF/AFL/AT recurrences following the 3-month blanking period through a minimum of 36-month follow-up from the date of the ablation procedure in the absence of Class I and III antiarrhythmic drug therapy.
Recurrent AF/AFL/AT Recurrent AF/AFL/AT is defined as AF/AFL/AT of at least 30 seconds' duration that is documented by an ECG or device recording system and occurs following catheter ablation. Recurrent AF/AFL/AT may occur within or following the post ablation blanking period. Recurrent AF/AFL/AT that occurs within the postablation blanking period is not considered a failure of AF ablation. Early recurrence of AF/AFL/AT Early recurrence of AF/AFL/AT is defined as a recurrence of atrial fibrillation within three months of ablation.
Episodes of atrial tachycardia or atrial flutter should also be classified as a "recurrence." These are not counted toward the success rate if a blanking period is specified.

## Recurrence of af/afl/at
Recurrence of AF/AFL/AT postablation is defined as a recurrence of atrial fibrillation more than 3 months following AF ablation. Episodes of atrial tachycardia or atrial flutter should also be classified as a "recurrence."
Late recurrence of AF/ AFL/AT Late recurrence of AF/AFL/AT is defined as a recurrence of atrial fibrillation 12 months or more after AF ablation. Episodes of atrial tachycardia or atrial flutter should also be classified as a "recurrence."
Blanking period A blanking period of three months should be employed after ablation when reporting efficacy outcomes. Thus, early recurrences of AF/AFL/AT within the first 3 months should not be classified as treatment failure. If a blanking period of less than 3 months is chosen, it should be prespecified and included in the Methods section.

## Continued

## Stroke screening
A risk-based approach to determine the level of postablation stroke screening in clinical trials is recommended by the Task Force. For ablation devices with a lower risk of stroke and for which a stroke signal has not been reported, a minimum standardized neurological assessment of stroke should be conducted by a physician at baseline and at hospital discharge or 24 hours after the procedure, whichever is later. If this neurological assessment demonstrates new abnormal findings, the patient should have a formal neurological consult and examination with appropriate imaging (i.e., DW-MRI), used to confirm any suspected diagnosis of stroke. For devices in which a higher risk of stroke is suspected or revealed in prior trials, a formal neurological examination by a neurologist at discharge or 24 hours after the procedure, whichever is later, is recommended. Appropriate imaging should be obtained if this evaluation reveals a new neurological finding. In some studies in which delayed stroke is a concern, repeat neurological screening at 30 days postablation might be appropriate. Detectable AF/AFL/AT Detectable AF is defined as AF/AFL/AT of at least 30 seconds' duration when assessed with ECG monitoring. If other monitoring systems are used, including implantable pacemakers, implantable defibrillators, and subcutaneous ECG monitoring devices, the definition of detectable AF needs to be prespecified in the clinical trial based on the sensitivity and specificity of AF detection with the particular device. We recommend that episodes of atrial flutter and atrial tachycardia be included within the broader definition of a detectable AF/AFL/AT episode.
AF/AFL/AT burden It is reasonable for clinical trials to incorporate AF/AFL/AT burden as a secondary endpoint in a clinical trial of AF ablation. In stating this it is recognized that there are no conclusive data that have validated a rate of AF burden reduction as a predictor of patient benefit (i.e. reduction in mortality and major morbidities such as stroke, CHF, QOL, or hospitalization). If AF burden is included, it is important to predefine and standardize the monitoring technique that will be used to measure AF burden. Available monitoring techniques have been discussed in this document. Should AF burden be selected as an endpoint in a clinical trial, the chosen monitoring technique should be employed at least a month prior to ablation to establish a baseline burden of AF.

## Entrance block
Entrance block is defined as the absence, or if present, the dissociation, of electrical activity within the PV antrum.
Entrance block is most commonly evaluated using a circular multielectrode mapping catheter positioned at the PV antrum. Entrance block can also be assessed using detailed point-by-point mapping of the PV antrum guided by an electroanatomical mapping system. The particular method used to assess entrance block should be specified in all clinical trials. Entrance block of the left PVs should be assessed during distal coronary sinus or left atrial appendage pacing in order to distinguish far-field atrial potentials from PV potentials. It is recommended that reassessment of entrance block be performed a minimum of 20 minutes after initial establishment of PV isolation.
Procedural endpoints for AF ablation strategies not targeting the PVs Procedural endpoints for AF ablation strategies not targeting the PVs: The acute procedural endpoints for ablation strategies not targeting the PVs vary depending on the specific ablation strategy and tool. It is important that they be prespecified in all clinical trials. For example, if a linear ablation strategy is used, documentation of bidirectional block across the ablation line must be shown. For ablation of CFAEs, rotational activity, or non-PV triggers, the acute endpoint should at a minimum be elimination of CFAEs, rotational activity, or non-PV triggers. Demonstration of AF slowing or termination is an appropriate procedural endpoint, but it is not required as a procedural endpoint for AF ablation strategies not targeting the PVs.

## Esophageal temperature monitoring
Esophageal temperature monitoring should be performed in all clinical trials of AF ablation. At a minimum, a single thermocouple should be used. The location of the probe should be adjusted during the procedure to reflect the location of energy delivery. Although this document does not provide formal recommendations regarding the specific temperature or temperature change at which energy delivery should be terminated, the Task Force does recommend that all trials prespecify temperature guidelines for termination of energy delivery.

## Enrolled subject
An enrolled subject is defined as a subject who has signed written informed consent to participate in the trial in question.

## Exit block
Exit block is defined as the inability to capture the atrium during pacing at multiple sites within the PV antrum. Local capture of musculature within the pulmonary veins and/or antrum must be documented to be present to make this assessment. Exit block is demonstrated by a dissociated spontaneous pulmonary vein rhythm.

## Nonablative strategies
The optimal nonablative therapy for patients with persistent and long-standing persistent AF who are randomized to the control arm of an AF ablation trial is a trial of a new Class I or III antiarrhythmic agent or a higher dose of a previously failed antiarrhythmic agent. For patients with persistent or long-standing persistent AF, performance of a direct-current cardioversion while taking the new or dose adjusted antiarrhythmic agent should be performed, if restoration of sinus rhythm is not achieved following initiation and/or dose adjustment of antiarrhythmic drug therapy. Failure of pharmacological cardioversion alone is not adequate to declare this pharmacological strategy unsuccessful.
Noninducibility of atrial fibrillation Noninducibility of atrial fibrillation is defined as the inability to induce atrial fibrillation with a standardized prespecified pharmacological or electrical stimulation protocol. The stimulation protocol should be prespecified in the specific clinical trial. Common stimulation approaches include a high-dose isoproterenol infusion protocol or repeated atrial burst pacing at progressively more rapid rates.

## Continued

## Guidelines

## Patient populations for inclusion in clinical trials
It is considered optimal for clinical trials to enroll patients with only one type of AF: paroxysmal, persistent, or longstanding persistent. If more than one type of AF patient is enrolled, the results of the trial should also be reported separately for each of the AF types. It is recognized that "early persistent" AF responds to AF ablation to a similar degree as patients with paroxysmal AF and that the response of patients with "late persistent AF" is more similar to that in those with long-standing persistent AF.
Therapy consolidation period Following a 3-month blanking period, it is reasonable for clinical trials to incorporate an additional 1-to 3-month therapy consolidation period. During this time, adjustment of antiarrhythmic medications and/or cardioversion can be performed. Should a consolidation period be incorporated into a clinical trial design, the minimum followup duration should be 9 months following the therapy consolidation period. Performance of a repeat ablation procedure during the blanking or therapy consolidation period would "reset" the endpoint of the study and trigger a new 3-month blanking period. Incorporation of a therapy consolidation period can be especially appropriate for clinical trials evaluating the efficacy of AF ablation for persistent or long-standing persistent AF. The challenge of this approach is that it prolongs the overall study duration. Because of this concern regarding overall study duration, we suggest that the therapy consolidation period be no more than 3 months in duration following the 3-month blanking period.

## Recommendations regarding repeat ablation procedures
It is recommended that all clinical trials report the single procedure efficacy of catheter ablation. Success is defined as freedom from symptomatic or asymptomatic AF/AFL/AT of 30 seconds or longer at 12 months postablation.
Recurrences of AF/AFL/AT during the first 3-month blanking period post-AF ablation are not considered a failure. Performance of a repeat ablation procedure at any point after the initial ablation procedure should be considered a failure of a single procedure strategy. It is acceptable for a clinical trial to choose to prespecify and use a multiprocedure success rate as the primary endpoint of a clinical trial. When a multiprocedure success is selected as the primary endpoint, efficacy should be defined as freedom from AF/flutter or tachycardia at 12 months after the final ablation procedure. In the case of multiple procedures, repeat ablation procedures can be performed at any time following the initial ablation procedure. All ablation procedures are subject to a 3-month post blanking window, and all ablation trials should report efficacy at 12 months after the final ablation procedure. Cardioversion definitions We recommend that the term "Maze" procedure is appropriately used only to refer to the biatrial lesion set of the Cox-Maze operation. It requires ablation of the RA and LA isthmuses. Less extensive lesion sets should not be referred to as a "Maze" procedure, but rather as a surgical AF ablation procedure. In general, surgical ablation procedures for AF can be grouped into three different groups: (1) a full biatrial Cox-Maze procedure; (2) PVI alone; and (3) PVI combined with left atrial lesion sets.
Hybrid epicardial and endo-

## Cardial af ablation
This term refers to a combined AF ablation procedure involving an off-pump minimally invasive surgical AF ablation as well as a catheter-based AF ablation procedure designed to complement the surgical lesion set. Hybrid ablation procedures may be performed in a single-procedure setting in a hybrid operating room or a cardiac catheterization laboratory environment, or it can be staged. When staged, it is most typical to have the patient undergo the minimally invasive surgical ablation procedure first following by a catheter ablation procedure 1 to 3 months later. This latter approach is referred to as a "staged Hybrid AF ablation procedure." (1) The minimum effectiveness endpoint is freedom from symptomatic and asymptomatic episodes of AF/AFL/AT recurrences at 12 months following ablation, free from antiarrhythmic drug therapy, and including a prespecified blanking period.
Minimum chronic acceptable success rate: paroxysmal AF at 12-month follow-up If a minimum chronic success rate is selected as an objective effectiveness endpoint for a clinical trial, we recommend that the minimum chronic acceptable success rate for paroxysmal AF at 12-month follow-up is 50%.
Minimum chronic acceptable success rate: persistent AF at 12-month follow-up If a minimum chronic success rate is selected as an objective effectiveness endpoint for a clinical trial, we recommend that the minimum chronic acceptable success rate for persistent AF at 12-month follow-up is 40%.
Minimum chronic acceptable success rate: long-standing persistent AF at 12-month follow-up If a minimum chronic success rate is selected as an objective effectiveness endpoint for a clinical trial, we recommend that the minimum chronic acceptable success rate for long-standing persistent AF at 12-month follow-up is 30%.
Minimum follow-up screening for paroxysmal AF recurrence For paroxysmal AF, the minimum follow-up screening should include (1) 12-lead ECG at each follow-up visit; (2) 24-hour Holter at the end of the follow-up period (e.g., 12 months); and (3) event recording with an event monitor regularly and when symptoms occur from the end of the 3-month blanking period to the end of follow-up (e.g., 12 months).
Minimum follow-up screening for persistent or longstanding AF recurrence
For persistent and long-standing persistent AF, the minimum follow-up screening should include (1) All studies should report freedom from AF, atrial tachycardia, and atrial flutter. These endpoints can also be reported separately. All studies should also clearly specify the type and frequency of ECG monitoring as well as the degree of compliance with the prespecified monitoring protocol.

## Section 11: training requirements
This section of the document outlines the training requirements for those who wish to perform catheter ablation of AF.

## Section 12: surgical and hybrid af ablation
Please refer to [fig_ref] Table 2: A subset of operators empirically isolates the SVC [/fig_ref] and [fig_ref] Figure 8: Indications for surgical ablation of atrial fibrillation [/fig_ref] presented earlier in this Executive Summary.

## Section 13: clinical trial design
Although there have been many advances made in the field of catheter and surgical ablation of AF, there is still much to be learned about the mechanisms of initiation and maintenance of AF and how to apply this knowledge to the still-evolving techniques of AF ablation. Although single-center, observational reports have dominated the early days of this field, we are quickly moving into an era in which hypotheses are put through the rigor of testing in well-designed, randomized, multicenter clinical trials. It is as a result of these trials that conventional thinking about the best techniques, success rates, complication rates, and long-term outcomes beyond AF recurrence-such as thromboembolism and mortality-is being put to the test. The ablation literature has also seen a proliferation of meta-analyses and other aggregate analyses, which reinforce the need for consistency in the approach to reporting the results of clinical trials. This section reviews the minimum requirements for reporting on AF ablation trials. It also acknowledges the potential limitations of using specific primary outcomes and emphasizes the need for broad and consistent reporting of secondary outcomes to assist the end-user in determining not only the scientific, but also the clinical relevance of the results [fig_ref] Table 3: Atrial fibrillation ablation [/fig_ref].

## Unanswered questions in af ablation
There is still much to be learned about the mechanisms of AF, techniques of AF ablation, and long-term outcomes. The following are unanswered questions for future investigation:
(1) AF ablation and modification of stroke risk and need for ongoing oral anticoagulation (OAC): The CHA 2 DS 2 -VASc score was developed for patients with clinical AF. If a patient has received a successful ablation such that he/she no longer has clinical AF (subclinical, or no AF), then what is the need for ongoing OAC? Are there any patients in whom successful ablation could lead to discontinuation of OAC? (2) Substrate modification in catheter-based management of AFparticularly for persistent AF: What is the proper lesion set required beyond pulmonary vein isolation? Do lines and complex fractionated atrial electrogram (CFAE) have any remaining role? Are these approaches ill-advised or simply discouraged? What is the role of targeting localized rotational activations? How do we ablate a localized rotational activation? How can scar be characterized and targeted for ablation? Do we need to replicate the MAZE procedure? Does the right atrium need to be targeted as well as the left atrium? (3) Autonomic influence in AF: Is clinical AF really an autonomic mediated arrhythmia? Is elimination of ganglionated plexi required? Is there a role for autonomic modulation, for example, spinal cord or vagal stimulation? (4) Contribution and modulation of risk factors on outcomes of AF ablation: Obesity reduction has been shown to reduce AF burden and recurrence in patients undergoing ablation. What is the role of bariatric surgery? Does the modulation of other risk factors influence outcome such as hypertension, sleep apnea, and diabetes? (5) Outcomes in ablation of high-risk populations: Do high-risk populations benefit from AF ablation? Congestive heart failure has been assessed in smaller trials, but larger trials are required. Outcome data are needed in patients with very enlarged LAs, hypertrophic cardiomyopathy, patients with renal failure on dialysis, and the very elderly. (6) Surgical vs catheter-based vs hybrid ablation: There should be more comparative work between percutaneous and minimally invasive surgical approaches. Both report similar outcomes, but there is a dearth of comparative data. Is there any patient benefit to hybrid procedures? (7) How do we characterize patients who are optimal candidates for ablation? Preablation late gadolinium-enhanced (LGE)-magnetic resonance imaging (MRI) might identify patients with heavy burdens of scar who are unlikely to respond to ablation. These techniques must become reproducible and reliable and must be assessed in multicenter trials. Other markers need to be investigated, including genetic markers, biochemical markers, and clinical markers based on aggregated risk scores. (8) The incremental role of new technologies: As newer and often more expensive technologies are produced for AF ablation, their definitive incremental value must be determined in order to justify change in practice or case cost. These technologies include global (basket) mapping techniques, newer ablation indices for assessing lesion durability, advanced imaging for viewing lesions in the myocardium, etc. New energy sources, including laser, low-intensity ultrasound, photonic particle therapy, external beam ablation, and MRI-guided ablation, must be assessed in comparative fashion. (9) Outcomes of AF ablation: We need to better understand the clinical relevance of ablation outcomes. What is the significance of time to recurrence of 30 seconds of arrhythmia? How do we best quantify AF burden? How do these outcomes relate to quality of life and stroke risk? (10) What is the role of surgical LA reduction? Does left atrial appendage (LAA) occlusion or obliteration improve outcome of persistent AF ablation with an accompanying reduction in stroke? Does ablation work through atrial size reduction? What is the incidence of "stiff atrial" syndrome and does this mitigate the clinical impact of ablation? (11) Working in teams: What is the role of the entire heart team in AF ablation? Does a team approach achieve better outcomes than a "silo" approach? An acute or subacute clinically overt bleed that does not meet the criteria for a major bleed but prompts a clinical response such that it leads to one of the following: hospital admission for bleeding; physician-guided medical or surgical treatment for bleeding; change in antithrombotic therapy (including interruption or discontinuation).
Minor bleeding (ISTH definition)
All nonmajor bleeds. Minor bleeds are further divided into clinically relevant and not. Continued Guidelines (12) Improving the safety of catheter ablation: As ablation extends to more operators and less experienced operators, the statistical occurrence of complications will increase. We need newer techniques to minimize complications and institute standards for operators to improve the reproducibility of ablation results and safety profiles at a variety of centers worldwide. (13) How does catheter ablation affect mortality, stroke, and hospitalization in broad and selected patient populations receiving catheter ablation for AF? (14) Management of patients who fail initial attempts at catheter ablation: Should there be specific criteria for repeat ablations (e.g., atrial size, body mass index)? Should patients be referred for surgery for repeat ablation?
In order to address these and other important questions in the field of catheter and surgical AF ablation, we urge investigators to create and participate in multisite collaborations and electrophysiology research networks with involvement of senior and junior investigators on the steering committees to push forward the next phase of AF research. We also urge funding bodies to support these important initiatives.

# Section 14: conclusion
Catheter ablation of AF is a very commonly performed procedure in hospitals throughout the world. This document provides an up-todate review of the indications, techniques, and outcomes of catheter and surgical ablation of AF. Areas for which a consensus can be reached concerning AF ablation are identified, and a series of consensus definitions have been developed for use in future clinical trials of AF ablation. Also included within this document are recommendations concerning indications for AF ablation, technical performance of this procedure, and training. It is our hope to improve patient care by providing a foundation for those involved with care of patients with AF as well as those who perform AF ablation. It is recognized that this field continues to evolve rapidly and that this document will need to be updated. Successful AF ablation programs optimally
[fig] Figure 1: Anatomical drawings of the heart relevant to AF ablation. This series of drawings shows the heart and associated relevant structures from four different perspectives relevant to AF ablation. This drawing includes the phrenic nerves and the esophagus. (A) The heart viewed from the anterior perspective. (B) The heart viewed from the right lateral perspective. (C) The heart viewed from the left lateral perspective. (D) The heart viewed from the posterior perspective. (E) The left atrium viewed from the posterior perspective. Illustration: Tim Phelps V C 2017 Johns Hopkins University, AAM. [/fig]
[fig] Figure 2: This figure includes six CT or MR images of the left atrium and pulmonary veins viewed from the posterior perspective. Common and uncommon variations in PV anatomy are shown. (A) Standard PV anatomy with 4 distinct PV ostia. (B) Variant PV anatomy with a right common and a left common PV. (C) Variant PV anatomy with a left common PV with a short trunk and an anomolous PV arising from the right posterior left atrial wall. (D) and (E) Variant PV anatomy with a common left PV with a long trunk. (F) Variant PV anatomy with a massive left common PV. [/fig]
[fig] Figure 3: Schematic drawing showing various hypotheses and proposals concerning the mechanisms of atrial fibrillation. (A) Multiple wavelets hypothesis. (B) Rapidly discharging automatic foci. (C) Single reentrant circuit with fibrillatory conduction. (D) Functional reentry resulting from rotors or spiral waves. (E) AF maintenance resulting from dissociation between epicardial and endocardial layers, with mutual interaction producing multiplying activity that maintains the arrhythmia. [/fig]
[fig] Figure 4: Structure and mechanisms of atrial fibrillation. (A) Schematic drawing of the left and right atria as viewed from the posterior perspective. [/fig]
[fig] Figure 5: Schematic drawing showing mechanisms of atrial flutter and atrial tachycardia. (A) Isthmus-dependent reverse common (clockwise) atrial flutter. (B) Isthmus-dependent common (counter clockwise) atrial flutter. (C) Focal atrial tachycardia with circumferential spread of activation of the atria (can arise from multiple sites within the left and right atrium). (D) Microreentrant atrial tachycardia with circumferential spread of activation of the atria. (E) Perimitral atrial flutter. (F) Roof-dependent atrial flutter. [/fig]
[fig] Figure 6: Schematic of common lesion sets employed in AF ablation. (A) [/fig]
[fig] Figure 7: Indications for catheter ablation of symptomatic atrial fibrillation. Shown in this figure are the indications for catheter ablation of symptomatic paroxysmal, persistent, and long-standing persistent AF. The Class for each indication based on whether ablation is performed after failure of antiarrhythmic drug therapy or as firstline therapy is shown. Please refer toTable 2Band the text for the indications for catheter ablation of asymptomatic AF. [/fig]
[fig] Figure 8: Indications for surgical ablation of atrial fibrillation. Shown in this figure are the indications for surgical ablation of paroxysmal, persistent, and long-standing persistent AF. The Class for each indication based on whether ablation is performed after failure of antiarrhythmic drug therapy or as first-line therapy is shown. The indications for surgical AF ablation are divided into whether the AF ablation procedure is performed concomitantly with an open surgical procedure (such as mitral valve replacement), a closed surgical procedure (such as coronary artery bypass graft surgery), or as a stand-alone surgical AF ablation procedure performed solely for treatment of atrial fibrillation.Guidelines [/fig]
[fig] Figure 9: Schematic drawing showing catheter ablation of atrial fibrillation using either RF energy or cryoballoon AF ablation. (A) Shows a typical wide area lesion set created using RF energy. Ablation lesions are delivered in a figure of eight pattern around the left and right PV veins. Also shown is a linear cavotricuspid isthmus lesion created for ablation of typical atrial flutter in a patient with a prior history of typical atrial flutter or inducible isthmus-dependent typical atrial flutter at the time of ablation. A multielectrode circular mapping catheter is positioned in the left inferior PV. (B) Shows an ablation procedure using the cryoballoon system. Ablation lesions have been created surrounding the right PVs, and the cryoballoon ablation catheter is positioned in the left superior PV. A through the lumen multielectrode circular mapping catheter is positioned in the left superior PV. Illustration: Tim Phelps V C 2017 Johns Hopkins University, AAM. [/fig]
[table] Table 2: A subset of operators empirically isolates the SVC. (D) Representative sites for ablation when targeting rotational activity or CFAEs are targeted. Modified with permission from Calkins et al. Heart Rhythm 2012; 9:632-696.e21. 2 .................................................................................................................................................................................................................... Indications for catheter (A and B) and surgical (C, D, and E) ablation of atrial fibrillation Indications for surgical ablation of atrial fibrillation C. Indications for concomitant open (such as mitral valve) surgical ablation of atrial fibrillation [/table]
[table] Table 3: Atrial fibrillation ablation: strategies, techniques, and endpoints [/table]
[table] Table 8: Definitions of complications associated with AF ablation [/table]
[table] Table 10: Definitions for use when reporting outcomes of AF ablation and in designing clinical trials of catheter or surgical ablation of AF [/table]
[table] Table 11: Quality-of-life scales, definitions, and strengths [/table]
[table] Table 12: Non-AF recurrence-related endpoints for reporting in AF ablation trials An acute episode of focal or global neurological dysfunction caused by brain, spinal cord, or retinal vascular injury as a result of hemorrhage or infarction. Symptoms or signs must persist > _24 hours, or if documented by CT, MRI or autopsy, the duration of symptoms/signs may be less than 24 hours. Stroke may be classified as ischemic (including hem- [/table]