Methods:

Patients at three academic hospitals in Hamilton, Ontario with a documented first-time episode of AF during hospitalization for medical illness or NCS, no known prior AF diagnosis, and who returned to sinus rhythm at the time of hospital discharge were eligible to participate in this study. Subjects were followed for 1 year, by 14-day rhythm monitoring by a wearable patch at 1 month and 6 months, and by telephone follow-up at 1 month, 6 months, and 1 year after hospital discharge.

The primary outcome was any AF episode lasting ≥30 seconds, detected by wearable monitor or during clinical care. Secondary outcomes included time from discharge to AF recurrence, total AF burden, total AF duration, longest AF episode, adverse events (death, heart failure, stroke, bleeding, or hospitalization for myocardial infarction or heart failure), and use of anticoagulation within 12 months after enrollment. Patients from the same hospital units with no AF history, matched by age and sex, were recruited as controls. Sensitivity analysis was performed comparing indication for index hospitalization (medical illness vs. NCS), cases treated with electrical or chemical cardioversion compared to those in which the AF terminated spontaneously, and subjects whose postdischarge AF diagnosis was based on clinical encounter versus wearable patch.