In approximately 30% of young survivors of stroke, no clear cause is identified despite a thorough evaluation.1 Patent foramen ovale is found on transesophageal echocardiography in about half of these patients, as compared with approximately 25% of the general population. Clinicians, then, often assume that the patent foramen ovale was the cause of the stroke, although it may be incidental in some patients.2–4 The most effective strategy for the prevention of stroke recurrence in such patients is uncertain, and some experts recommend closure of the patent foramen ovale to prevent future embolic events, although high-level data have been lacking. . . .