How much atrial fibrillation is too much after ablation of paroxysmal atrial fibrillation? Insights from the COMPARE CRYO study using continuous rhythm monitoring

Recurrence after pulmonary vein isolation (PVI) is currently defined as any atrial arrhythmia lasting >30s. While there is general agreement that this definition is suboptimal, it is unclear what alternative efficacy endpoint definitions would relate best to the patients’ disease burden and to metrics of healthcare utilization.

To evaluate the impact of alternative efficacy endpoints after PVI based on AF burden, longest AF episode duration and number of episodes on patients’ disease burden and on metrics of healthcare utilization 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 timing and duration of every episode as well as the total number of episodes and AF burden were evaluated between 91-365 days. Patients were classified on the basis of AF burden, duration of the longest AF episode, and the number of AF episodes. Outcomes of redo procedures, AF-related hospitalizations (including cardioversions) and change in quality of life (EQ5D) score were assessed.

For the 201 patients enrolled in the study, the primary endpoint of AF/AT recurrence occurred in 44% (89) patients. A total of 6104 arrhythmia episodes occurring between days 91 and 365 were analyzed. Rates of redo ablations and AF-related hospitalizations were lowest in patients with AF burden <0.1%, AF episode durations <1h or <6 AF episodes, respectively (Figure 1, Panel A-C). This increased for AF burden >0.1%, AF episode duration >1h, and >6 AF episodes and was highest for AF burden >1%, AF episode duration >24h, and >33 AF episodes (Figure 1, Panel A-C). Patients with their longest episode >24h had a reduced EQ-5D score at 12 months from baseline (p=0.008).

Alternative efficacy endpoints based on AF burden, AF episode duration or number of AF episodes have a significant impact on healthcare utilization metrics. AF burden >0.1%, AF episode duration >1h and more than 6 AF episodes resulted in increased rates of redo procedures and AF-related hospitalizations.

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