Patent foramen ovale (PFO) closure is reported to result in fewer episodes of clinically manifest recurrent cerebral ischemia than medical treatment. We evaluated by means of magnetic resonance imaging (MRI) whether silent cerebral ischemic episodes are also decreased by PFO closure. Seventy-one patients with PFO were selected for percutaneous closure of PFO at our center. All had PFO with large right-to-left shunt documented by transcranial Doppler ultrasound and transesophageal echocardiography, > or =1 previous stroke or transient ischemic attack with MRI documentation at the index event, and no alternative cause for cerebral ischemia. MRI studies were performed in all patients 24 hours before the procedure and at 1-year follow-up (or before in the case of a suspected new neurologic event). Eight patients (11%) had >1 clinical event before the procedure. Comparing the 2 MRI studies before the procedure, silent ischemic lesions were observed in 14 other patients (20%). Thus, considering clinical and silent events together, >1 event was present at baseline in 22 patients (31%). After PFO closure (follow-up 16 +/- 7 months), 1 recurrent neurologic event occurred (1%, p = 0.02 vs preprocedural clinical events); however, urgent brain MRI results were negative. Moreover, only 1 patient showed 1 new silent lesion at brain MRI at follow-up (1%, p <0.001 vs preprocedural silent brain lesions). Considering clinical and silent events, relapses occurred in 2 patients only (p <0.001 vs before procedure). Recurrent events were limited to those with incomplete PFO closure at postprocedural transcranial Doppler ultrasound (p = 0.02). In conclusion, percutaneous PFO closure results in few clinical or silent events after 1-year follow-up, especially when complete PFO closure is successfully accomplished.