Prognostic Impact of Spontaneous Conversion to Sinus Rhythm in Patients With Symptomatic Paroxysmal Atrial Fibrillation: A Propensity-Matched Follow-Up Study.

BACKGROUND: Paroxysmal atrial fibrillation (PAF) patients do not invariably progress to persistent AF, with a consistent group of patients showing AF regression during follow-up. The prognostic implications of spontaneous conversion (SCV) to sinus rhythm (SR) in those patients has never been evaluated yet. OBJECTIVE: To evaluate the long-term prognostic impact of early SCV to SR in patients presenting with symptomatic, hemodynamically stable, PAF in the emergency department (ED). METHODS: Consecutive patients with symptomatic, hemodynamically stable PAF were included. Patients discharged in SR and followed-up thereafter were stratified based on the occurrence of SCV within 6 h from ED admission. Propensity score matching (PSM) was employed to adjust for relevant baseline differences. The primary outcome was a composite of progression to permanent AF, progression to persistent AF, initiation of antiarrhythmic drugs, AF ablation and need for pharmacologic or electrical cardioversion. Secondary outcomes included AF episodes frequency and individual components of the composite outcome. RESULTS: Out of 158 patients, 52 experienced SCV while 106 required active cardioversion. After PSM, 52 matched pairs were analyzed. During a median follow-up of 17.0 months (IQR: 12.8-21.3 months), the primary composite outcome occurred significantly less frequently in the SCV group compared to the non-SCV group (21 vs. 41 events; log-rank p < 0.001). SCV was associated with a significant reduction of primary outcome occurrence (OR 0.361 [95% CI: 0.176; 0.739], p-value 0.005). The SCV group also exhibited a lower arrhythmic burden, with fewer AF episodes (median 1 [3] vs. 2 [4], p < 0.001) and reduced need for cardioversion (p = 0.008). The primary and secondary outcomes did not differ among SCV and non-SCV groups in the unmatched population. CONCLUSIONS: SCV in patients with PAF is associated with lower arrhythmic burden and reduced need for rhythm-control strategies at follow-up.