PFO and cryptogenic stroke: Do we finally have closure?

In up to 40 percent of patients with acute ischemic stroke, the etiology remains uncertain [1]. The association of a PFO with stroke in a young woman with cerebral arterial embolism was first described in 1877 [2]. Lechat et al. later described the high prevalence of PFO in adults younger than 55 years of age when no identifiable cause of stroke could be identified [3]. They suggested that paradoxical embolism through the PFO may be responsible for stroke more often than had been suspected. Further studies suggested that the size and the degree of shunting as identified by transesophageal echocardiography were important determinates of ischemic stroke and recurrent strokes. Furthermore, the presence of both a patent foramen ovale and atrial septal aneurysm were determinants of a substantial risk for recurrent stroke in individuals with a previous stroke of unknown origin despite the use of aspirin [4]. When aspirin was compared to warfarin in patients with PFO, there was no difference in the rates of adverse events or in the time to the first event, thus raising the speculation that closure of the PFO may decrease the incidence of recurrent events over medical therapy alone [5].