Impact of alternative efficacy end point definitions on reported outcomes after ablation of paroxysmal atrial fibrillation - Insights from the COMPARE-CRYO study using continuous rhythm monitoring.

Abstract

Background: Recurrence after atrial fibrillation (AF) ablation is commonly defined as any atrial arrhythmia lasting ≥30 seconds. It is unclear how alternative efficacy end point definitions would change the observed success rates and how they would relate to patients' disease burden or health care utilization metrics.

Objective: This study aimed to evaluate the impact of alternative end point definitions after AF ablation based on AF-burden, duration or number of episodes using implantable cardiac monitors (ICM).

Methods: This is a prespecified substudy of the COMPARE-CRYO (COMPARison of the PolarX and the Arctic Front CRYOballoon for pulmonary vein isolation) study, which enrolled patients with paroxysmal AF undergoing cryoballoon ablation. All patients underwent ICM implantation, and the blanking period was 90 days. Details were collected on timing, duration, and number of episodes, and AF-burden between 91-365 days. Outcome measures were redo ablations and AF-related hospitalizations.

Results: The primary end point of any recurrence lasting ≥30 seconds occurred in 89 of 201 patients (44%). One-year success rates increased with increasing arrhythmia duration thresholds from 56% (≥30 sec) to 97% (≥24 hrs), with number of episode thresholds from 56% (≥1 episode) to 98% (≥100 episodes) and with AF-burden thresholds from 56% (AF-burden >0%) to 93% (AF-burden >2%). Rates of redo ablations and AF-related hospitalizations increased for AF-episode durations >1 hour, >6 AF-episodes, and an AF-burden >0.1%, and were highest for AF-episode durations >24 hours, >33 AF-episodes, and an AF-burden >1%.

Conclusion: Alternative efficacy end point definitions have a significant impact on reported outcomes and health care utilization metrics after AF ablation. These findings are important when considering end point definitions other than the traditional 30 seconds in the design of future AF-ablation trials.