Heterogeneity in endpoints, monitoring methods and blanking periods in clinical trials of atrial fibrillation ablation: a systematic review and meta-analysis

BACKGROUND: Catheter ablation is a cornerstone of rhythm control in atrial fibrillation (AF). It is important that clinical trials in AF ablation have comparable endpoints and outcomes. We performed a systematic review of randomised controlled trials (RCTs) in AF ablation to evaluate endpoint definitions, monitoring methods, follow-up protocols and blanking periods. METHODS: Electronic databases were searched for RCTs in catheter ablation for AF with ≥ 100 patients and ≥ 6 months of follow-up. Data were collected on study characteristics, patient demographics, arrhythmia monitoring methods, blanking periods, arrhythmia endpoints. RESULTS: 129 RCTs (n = 31,406) met inclusion criteria; 114 studies involved radiofrequency ablation and 43% patients had persistent AF. There were 19 different definitions of arrhythmia endpoints; the most common was AF/atrial tachyarrhythmia ≥ 30 s (102/129; 79%). Composite endpoints were used in 55 studies (43%). There were 11 different methods of monitoring arrhythmia recurrence; 24-h Holter (67/129; 52%) was most frequent, followed by transtelephonic/event-triggered monitoring (50/129; 39%), then 7-day Holter monitors (30/129; 23%). In the first year of follow-up, arrhythmia recurrence was most commonly assessed at 6 months (120/129; 93%), 12 months (117/129; 91%), and 3 months (116/129; 90%); 56 trials (43%) reported 1-month visit. Most trials used a 90-day blanking period (109/129, 84%). Recurrences during blanking period was reported in only 32 trials (25%). CONCLUSION: Significant heterogeneity exists in RCTs of AF ablation with varying definitions of arrhythmia recurrence, monitoring methods, follow-up schedules and blanking periods. Scientific consensus and more standardised assessment of arrhythmia recurrence is needed to improve comparability of clinical outcomes in RCTs of AF ablation.