25 to 40% of stokes are classified as cryptogenic, meaning no clear cause, such as atrial fibrillation or carotid stenosis, can be identified. Patent foramen ovale (PFO) is associated with recurrence of cryptogenic stroke, particularly in young patients.¹ The problem is that PFOs are very common and can be identified in 25% of the general population, and are not associated with an increase in the risk for stroke in this large group.² PFOs can be identified in about 65% of individuals aged < 55 years who are affected by cryptogenic stroke. Transcatheter device closure of a PFO may reduce the risk for recurrent stroke by closing the route for a paradoxical embolism. Observational studies showed that PFO closure is associated with an 84% lower risk for recurrent stroke.³ Initial studies of transcatheter closure of PFO did not show a benefit of closure over that of medical therapy alone. It is possible that the initial studies were not sufficiently long enough to show a benefit. 2 more recent studies with larger numbers and longer follow-up have shown a benefit. This meta-analysis of all studies shows that recurrence rate is low, but that transcatheter closure offers a better chance of not having a recurrent stroke than medical therapy alone. — Neil Skolnik, MD

1. Overell JR, Bone I, Lees KR. Interatrial septal abnormalities and stroke: A meta-analysis of case-control studies. Neurology. 2000;55:1172-1179.
2. Di Tullio MR, Sacco RL, Sciacca RR, Jin Z, Homma S. Patent foramen ovale and the risk of ischemic stroke in a multiethnic population. J Am Coll Cardiol. 2007;49:797-802.
3. Agarwal S, Bajaj NS, Kumbhani DJ, Tuzcu EM, Kapadia SR. Meta-analysis of transcatheter closure versus medical therapy for patent foramen ovale in prevention of recurrent neurological events after presumed paradoxical embolism. JACC Cardiovasc Interv. 2012;5:777-789. doi:10.1016/j.jcin.2012.02.021.