In patients who underwent patent foramen ovale closure (PFOc), post-implant AF (PIAF) occurred far more frequently than previously reported and was strongly linked with older age at PFOc, according to a study published in Catheterization & Cardiovascular Interventions. Robert J. Sommer, MD, and colleagues examined the incidence and time course of AF after PFOc using implantable loop recorders (ILR) placed during cryptogenic stroke assessment. Among 761 patients who underwent PFOc between January 2016 and December 2020, 35 received an ILR implanted before PFOc, without recorded AF, and were monitored for 1 month or more post-PFOc. Following PFOc, the mean duration of ILR was 54.6 weeks. AF was observed in 37% of patients. Patients who underwent PFOc and developed PIAF were older than those who did not (62 vs 52). In all but one patient with AF, the initial PIAF event occurred within 4 weeks of PFOc, with the highest frequency around 2 weeks. No recurrent strokes were reported during ILR monitoring.