Patent foramen ovale and ischemic stroke recurrence

During the last two decades, evidence has shown an association between patent foramen ovale (PFO) and cryptogenic stroke, predominantly in younger patients. In a meta-analysis of case-control studies, approximately 35%–50% of patients with cryptogenic ischemic stroke had a PFO, vs only 4%–10% of age-matched patients. That is a fivefold increase risk of cryptogenic stroke in younger patients with PFO.1 However, causality and its recurrence seem to be more complex, considering that 27% of the general population has this vestige of fetal circulation.2 The risk of stroke recurrence due to the failure of the primum and secundum septa to fuse postnatally is low. In the PFO-ASA trial, the recurrence in aspirin-treated patients was 2.3% in 4 years vs 4.2% observed in those without an interatrial septal abnormality. This risk strikingly increased to 15.2% if coexisting atrial septal aneurysm (ASA) was present.3 The ASA-PFO embolic mechanism is unclear but it is possibly related to motion dynamics influencing flow through the PFO leading to paradoxical emboli or possibly being a nidus for thrombus formation. In other …