Long-term monitoring after surgical ablation for atrial fibrillation: how much is enough?

INTRODUCTION: Evaluating and comparing the success of surgical ablation techniques in the treatment of atrial fibrillation is complicated by clinicians' use of varying techniques to measure the burden of atrial fibrillation after ablation. Intuitively, one would expect longer monitoring to be more accurate, picking up atrial fibrillation events occurring at a low rate, but how long is long enough? This study compared rates of normal sinus rhythm recorded after atrial fibrillation ablation in a cohort of patients monitored for a range of durations.
METHODS: Two hundred fifty-four patients (50.4% paroxysmal) underwent surgical ablation for treatment of atrial fibrillation. All patients were monitored at 6 months with both electrocardiography and either an event monitor or implanted pacemaker device that could be interrogated. Event monitoring and pacemaker data were analyzed for rhythm at 24 hours, 7 days, and 14 days; pacemaker data were also analyzed at 3 months.
RESULTS: In the overall group, we found that rates of normal sinus rhythm detected were greatest with electrocardiography (91.7%) and decreased significantly at each of the longer durations (88.2% at 24 hours, 82.7% at 7 days, 81.1% at 14 days). Pacemaker data from a subset of patients revealed minimal or no statistically significant changes from 7 days to 3 months. Results were consistent across types of atrial fibrillation.
CONCLUSIONS: These findings suggest that rhythm measurements in patients with atrial fibrillation differ according to the measurement duration used. We recommend longer-term monitoring, with 7 days providing both good accuracy and good patient compliance.