Pre-Procedural Time Spent in Atrial Fibrillation Using Intermittent ECG Monitoring Is Associated with Arrhythmia Recurrence After Ablation: The ISOLATION Cohort Study

AIMS: Atrial fibrillation (AF) is conventionally classified as paroxysmal or persistent. AF burden might better reflect response to rhythm-control interventions. This study evaluated the association between estimated pre-procedural time spent in AF and recurrences after AF ablation, compared with conventional AF classification. METHODS AND RESULTS: In patients scheduled for AF ablation, clinical characteristics were collected before ablation, and 60-second single-lead ECGs were recorded three times daily (with additional symptom-triggered recordings) for four weeks. Pre-procedural time spent in AF was estimated as the number of days with detected AF divided by total monitoring days. The primary endpoint was AF recurrence between 3 and 12 months post-ablation. Of 302 patients (mean age 64 ± 9 years; 33% female), 201 (67%) had paroxysmal AF and 101 (33%) had persistent AF. After 12 months, recurrence rates were higher in persistent than in paroxysmal AF (37.6% vs. 24.4%, P & 0.01) and in patients with a higher (>32%) vs. lower (≤32%) percentage of time spent in AF (36.4% vs. 24.0%, P < 0.01). Notably, paroxysmal AF patients with a higher percentage of time in AF had recurrence rates comparable to those of patients with persistent AF. Pre-procedural percentage of time in AF independently predicted arrhythmia recurrence at 12-month follow-up (HR: 1.06; 95% CI: 1.0-1.1; P & 0.025). CONCLUSION: A higher pre-procedural percentage of time spent in AF derived from 60-second single-lead ECGs is independently associated with atrial arrhythmia recurrence after ablation. Assessing the percentage of pre-procedural time spent in AF might help identify paroxysmal AF patients with a high AF recurrence risk in future studies.