Methods:

The investigators conducted an investigator-initiated, open-label, multicenter, randomized clinical trial at 10 Canadian centers. Enrollment spanned from March 2017–March 2020, with follow-up through September 11, 2020. As a result of the coronavirus disease 2019 (COVID-19) pandemic, enrollment stopped on July 17, 2020, at which point 85% of the proposed sample size was enrolled. Cardiac surgical patients with CHA₂DS₂-VASc (congestive heart failure, hypertension, age ≥75 years, diabetes, prior stroke or transient ischemic attack, vascular disease, age 65-74 years, female sex) score ≥4 or ≥2 with risk factors for postoperative atrial fibrillation (POAF), no history of preoperative AF, and POAF lasting <24 hours during hospitalization were enrolled. The intervention group underwent continuous cardiac rhythm monitoring with wearable, patch-based monitors for 30 days after randomization. Monitoring was not mandated in the usual care group within 30 days after randomization. The primary outcome was cumulative AF and/or atrial flutter lasting ≥6 minutes detected by continuous cardiac rhythm monitoring or by a 12-lead electrocardiogram within 30 days of randomization. Prespecified secondary outcomes included cumulative AF lasting ≥6 hours and ≥24 hours within 30 days of randomization, death, myocardial infarction, ischemic stroke, non–central nervous system thromboembolism, major bleeding, and oral anticoagulation prescription. Comparison of the proportion of patients between the two groups with the primary outcome was performed with the Pearson χ² test.