Clinical implications of atrial fibrillation recurrence vs. burden following catheter ablation: outcome data from 3 contemporary clinical trials using an insertable cardiac monitor

Background Recurrence of atrial fibrillation (AF) following catheter ablation is typically defined in clinical trials in a binary fashion, e.g. > 30 seconds or none. However, the clinical implications of this endpoint, adopted from formal guidelines, have been questioned. Purpose We hypothesized that assessment of AF burden can provide incremental clinical and management implications to the dichotomous definition of AF recurrence following ablation. Methods The study population comprised 147 patients enrolled in 3 ongoing multicenter randomized clinical trials (ICM REDUCE-AF [N=67]); HYBRID-AF (N=55] and DAPA-AF [N=25]), each employing an insertable cardiac monitor (ICM) to assess post-ablation AF recurrence and burden. The rate of cardiovascular (CV)-related healthcare utilization (CV-HCU, defined as the total number CV admissions, ED visits, cardioversions, procedures, and unplanned office visits) was compared based on AF recurrence (defined as >2 minutes of ICM-detected AF) vs. based on AF burden post-ablation (defined as time in AF divided by total monitoring time). Results Among the 147 study patients, mean age was 65 years; 53 (36%) were women; and 78 (53%) had persistent AF. At 12-months post-ablation (excluding blanking), the cumulative probability of AF recurrence was 60% (Figure 1A). However, 27% of AF recurrences were associated with a very low AF burden (≤0.1%) and low CV-HCU (10 events per 100 patient-months), similar to patients without AF recurrence (11 events per 100 patient-months). In contrast, recurrences with a higher AF burden (>0.1%; mean 17% ± 25%) were associated with a 3-fold higher rate of CV-HCU (31 events per 100 patient-months, p<0.001; Figure 1B). Findings were consistent regardless of AF-type, comorbidities or LVEF. Conclusions A substantial proportion of AF recurrences following contemporary AF ablation are associated with a very low AF burden without apparent effect on CV outcomes, whereas higher AF burden is associated with increased CV-HCU. These findings stress the need to move beyond a dichotomous definition of AF recurrence and to monitor AF burden post-ablation to guide management decisions in contemporary clinical practice.