Atrial fibrillation is a common complication of cardiothoracic surgery, occurring in 25% to 50% of patients before discharge.1 It is more common in older patients, those with chronic obstructive pulmonary disease, patients undergoing valve surgery, and those in whom β-blockers are withdrawn.1,2 Postoperative atrial fibrillation (POAF) is not benign and is associated with worse outcomes, including increased risks of stroke, all-cause mortality, length of hospital stay, and increased health care utilization.3 However, the risks of POAF are not transient nor limited to the days and months after surgery.4,5 Multiple studies have shown patients with POAF have a 4-fold to 8-fold increased risk of developing atrial fibrillation (AF) during long-term follow-up, compared with those without POAF.5-7 For example, in a study of patients undergoing cardiac surgery in Olmsted County, Minnesota, after a mean follow-up of 8 years, 43% of patients with new-onset POAF developed AF, compared with only 11% of patients without POAF.6