Impact of alternative efficacy endpoint definitions on reported outcomes after ablation of paroxysmal atrial fibrillation, insights from the COMPARE CRYO study using continuous rhythm monitoring

Recurrence after atrial fibrillation (AF) ablation is currently defined as any atrial arrhythmia lasting >30s. While it is generally agreed that this definition has limited value from a disease burden and patient perspective, data on the impact of alternative endpoint definitions for AF ablation is scarce.

To evaluate the impact of alternative endpoint definitions after AF ablation based on the arrhythmia duration, the number of episodes and AF burden using continuous rhythm monitoring by means of implantable cardiac monitors (ICM).

This is a prespecified sub study of the COMPARE-CRYO study, which enrolled patients with paroxysmal atrial fibrillation undergoing cryoballoon ablation. All patients underwent ICM implantation and the blanking period duration was 90 days. The time and duration of every atrial arrhythmia episode were evaluated.

For the 201 patients enrolled in the study, a total of 6104 arrhythmia episodes occurring between days 91 and 365 were analysed. The 1-year success rate increased with arrhythmia duration thresholds from 56% (≥30 sec) to 97% (≥24h, p<0.0001, Figure 1A). Similarly, the success rate increased with definitions based on the minimal number of episodes from 56% for a single episode of recurrence to 98% for at least 100 episodes of AF (p<0.001, Figure 1B). Definitions based on AF burden resulted in 1-year success rates from 56% for an AF-Burden >0% to 93% for an AF-Burden >2% (p<0.001, Figure 1C).

Alternative endpoint definitions based on arrhythmia duration, number of episodes or AF burden have a significant impact on the reported efficacy outcomes after AF ablation. Our findings are important when considering endpoint definitions other than the traditional 30 seconds in the design of future AF ablation trials.fig 1A

and fig 1B