Clinical Outcomes of Persistent Atrial Fibrillation Ablation Using Ablation Index-guided Radiofrequency Catheter Ablation in Patients With Continuous Monitoring

Atrial fibrillation (AF) is the commonest condition affecting the rhythm of the heart. Tablets to try to normalize the heart rhythm rarely work well. As a result, doctors have devised a treatment called catheter ablation in which special wires are used to deliver heat energy (called ablation lesions) on the inside surface of the heart. Unfortunately, in many patients (almost 1 in 2), some of these ablation lesions recover, and that leads to the recurrence of AF. Many of these patients then need a second procedure to deliver further ablation at these recovered areas.

Because of that problem, a software called Ablation Index has been developed to optimize the delivery of ablation lesions. The study aims to find out the effectiveness of the use of that Ablation Index in improving the ablation outcomes in patients with persistent AF. Also, the study will test the effectiveness of a new ablation approach using a catheter which is capable of delivering high-power during ablation and therefore requires shorter time for ablation. This will be achieved by following up patients who received ablation for 12 months to monitor their response to treatment in terms of freedom from AF.

This study will include patients with persistent AF which means AF episode(s) that last for longer than seven days. Patients participating in the study will undergo their ablation treatment either guided by ablation Index or delivered using high-power, short-duration (HPSD) ablation.

All participants will undergo implantation of a cardiac monitor, also knowns as loop recorder, to monitor for recurrence of atrial tachyarrhythmia following ablation. The monitor stores these ECG recordings which will be downloaded during review appointments that will be arranged 6 weeks, 3 months, 6 months and 12 months after the ablation procedure.

All participants will undergo implantation of a cardiac monitor, also knowns as a loop recorder, to monitor for recurrence of atrial tachyarrhythmia following ablation. The monitor stores these ECG recordings which will be downloaded during review appointments that will be arranged 6 weeks, 3 months, 6 months, and 12 months after the ablation procedure.

Single-center, prospective cohort study including patients with persistent AF (PeAF).

Primary Hypothesis:

Single AF ablation procedure that includes PVI achieved with point-by-point Wide Area Circumferential catheter ablation (WACA) either guided by Ablation Index (AI) targets or by HPSD ablation delivered using QDOT Micro catheter results in reduction in ATA as detected by insertable cardiac monitor (ICM).

Secondary hypotheses:

Single AF ablation procedure that includes PVI achieved with point-by-point WACA guided by Ablation Index targets has low incidence of adverse events and results in freedom from ATA, and improvement of AF symptoms and quality of life.

AF ablation procedures done by HPSD ablation delivered using QDOT Micro catheter will have shorter time and similar outcomes to procedures done using SmartTouch SF catheter guided by Ablation Index targets.

Eligibility Criteria:
Inclusion criteria:

* Aged over 18 years
* Persistent AF defined according to the 2017 HRS/EHRA/ECAS/APHRS/SOLAECE Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation, as AF episode that lasts longer than 7 days. (Calkins et al., 2017)
* Symptomatic despite drug treatment.
* Due to undergo AF ablation.

Exclusion criteria:

* Inability or unwillingness to receive oral anticoagulation with a Vitamin K antagonist (VKA) or non-VKA (NOAC) agent
* Previous catheter or surgical ablation procedure for AF
* Unwillingness or inability to complete the required follow-up arrangements
* Current pattern of paroxysmal AF
* Long standing persistent AF (continuous AF longer than 12 months before ablation)
* Prior prosthetic mitral valve replacement or severe structural cardiac abnormality
* Known infiltrative cardiomyopathy
* Known severe left ventricular systolic function (ejection fraction \<35%)
* Pregnancy