Unipolar Atrial Electrogram Modification Combined to the Contact Force Sensing Technology for Pulmonary Vein Isolation
Condition: Atrial Fibrillation; Arrhythmia
MeSH terms: Atrial Fibrillation
Study type: Observational

Summary: 
      Prospective observational multicentric study evaluating the efficacy of considering unipolar
      signal modification during radio frequency catheter ablation of patients with symptomatic
      paroxysmal atrial fibrillation in France between November 2013 and January 2015. All
      procedures were conducted according to the standard clinical care and current guidelines.
      Pulmonary vein isolation was guided according to force (at least 10 grams) and application
      vector (perpendicular to the wall) developed until the atrial unipolar electrogram recording
      became a complete positive signal. Patients were discharged from hospital free of any
      anti-arrhythmic drugs. Recurrence of arrhythmias at 12 months (primary outcome) was assessed
      by continuous 48-hour Holter at 1, 3, 6, 9 and 12 months post-catheter ablation.
    

Detailed description: 
      Patients and Setting: Consecutive patients referred to the participating institutions, from
      November 2013 to January 2015, for catheter ablation of symptomatic and drug resistant
      paroxysmal atrial fibrillation (AF) were enrolled in this observational 12-follow up study.
      Paroxysmal AF was defined as any episode of AF that terminates spontaneously in less than
      seven days. Eligibility criteria, as well as outcome measures have been detailed in other
      sections.

      Radiofrequency catheter ablation for AF: All procedures were conducted according to the
      standard clinical care and North American and European guidelines. Of note, the investigators
      did not assign specific interventions to the subjects of the study, and all interventions
      (trans-oesophageal echocardiography, pulmonary vein isolation) are recommended by American
      Heart Association and European Society of Cardiology. AF catheter ablation were conducted
      under efficient vitamin K antagonists (INR 2-3) and general anesthesia without
      discontinuation of anti-arrhythmic drugs (AAD). Trans-esophageal echocardiography was
      performed for each patient within 48 hours before the procedure to exclude any intra-cardiac
      thrombi. Two long sheaths (Preface™, Biosense Webster, Diamond Bar, CA or SLO™, Saint Jude
      Medical, Minnetonka, MN) were advanced into the LA after two trans-septal punctures.
      Intravenous heparin was administered with a target activated clotting time beyond 320
      seconds. Three catheters, inserted through the right femoral vein, were used for mapping and
      ablation: a 6F non deflectable hexapolar 2.5-2.5-2.5-2.5-247.5 mm interspacing electrodes
      catheter placed at the high right atrium (RA) or into the coronary sinus (CS) whenever
      possible (Curve: A-Josephson type, Biosense Webster), with its proximal electrode placed at
      the level of the inferior vena cava, a 7F circular decapolar mapping catheter (Lasso™) placed
      into the LA through one of the constantly perfused long sheaths and used to monitor PVI, and
      a 3.5 mm 7F externally irrigated-tip ablation contact force sensing catheter (SmartTouch™),
      placed within the LA through the second constantly irrigated long sheath. A LA anatomy shell
      was created with the aid of the Carto3 system (Biosense Webster). This shell was merged or
      not with 3D computed tomography scan acquired prior to the ablation procedure depending on
      operator's choice. Pulmonary veins were isolated two-by-two at their antral level by creating
      a continuous circular lesion. The carina regions were targeted only if PVs could not be
      isolated despite complete circular lesion creation around PVs ostia. Radiofrequency ablation
      settings used were: 30 W/48°C/17 ml per minute except for the posterior LA wall (25W/48°C/17
      ml per min) and the ridge (35W/48°C/30 ml per min). Thirty minutes after PVI, entrance and
      exit blocks were rechecked for each PV. In case of PV reconnection, supplemental RF
      applications were performed in order to re-isolate PVs following a two-step approach.

      Evaluation of the unipolar signal modification: every radiofrequency (RF) delivery was
      performed with a minimal 10 g of force, through the entire RF application and lasted 10
      seconds after the unipolar atrial electrogram, recorded by the ablation catheter, which
      always demonstrated positive-negative morphology before ablation, became complete positive
      signal (except on the posterior LA wall where 5 supplemental seconds only were added). During
      individual RF applications, the modification of the unipolar atrial electrogram was monitored
      in real-time with the Carto™ system at a sweep speed of 200mm/s. Reference annotation signal
      was recorded from the bipolar signal of either electrodes 1-2 or 3-4 of the non-deflectable
      6F hexapolar catheter, depending on whether the latter was placed into the CS or at the high
      RA. Unipolar signal was recorded from the 3.5mm distal electrode of the ablation catheter and
      was filtered on the Carto™ system with a [0.5-120] Hz band-pass filter and displayed in the
      Carto™ annotation viewer. The indifferent electrode was used as the cathode and was located
      at the level of the inferior vena cava.

      Post-ablation Management and Follow-up: All patients were discharged home within 3 days, and
      enrolled in a 12-month follow-up. Post-procedure, AAD were discontinued while vitamin K
      antagonists were prescribed for 3 months. Subsequently, vitamin K antagonists were continued
      or not, depending on the CHA2DS2-VASc score of each patient. Patients were evaluated
      pre-discharge, at 1, 3, 6, 9 and 12 months post-procedure. Information collected included
      details of cardiac medications, NYHA functional class and history of any arrhythmias or other
      adverse events. In addition, a 12-lead ECG and 24-hour Holter monitoring were systematically
      obtained at each visit. Echocardiography was performed in all cases the day after procedure.
      No antiarrhythmic medication was prescribed following ablation. If there was documented
      recurrence of symptomatic AF during the 3-month blanking period and the patient required
      antiarrhythmic drug therapy, a previously ineffective but tolerated class 1 or class 3
      (sotalol) drug was the preferred option. Atrial tachycardia/AF recurrence was considered, any
      episode lasting > 30 s (either symptomatic or asymptomatic) subsequent to a 3-month blanking
      period.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Consecutive patients referred to the participating institutions, from November 2013 to
        January 2015, for catheter ablation of symptomatic and drug resistant PAF. Paroxysmal AF
        was considered any episode of AF that terminates spontaneously in less than seven days.
      
Keywords: Catheter Ablation; Pulmonary Vein Isolation; Radiofrequency