Relationship Between Patent Foramen Ovale and Stroke Subtypes

Background: Contrast-enhanced transcranial Doppler ultrasonography is a sensitive non-invasive method for detecting a patent foramen ovale (PFO). The association between the clinical finding of a suchlike detected right-to-left shunt and ischemic stroke is still a matter of debate. We aimed to investigate the potential causal relationship in a population of unselected stroke patients. Methods: The records of 764 consecutive patients who were investigated at our institution were reviewed. For microembolic monitoring, a 2MHz pulse-wave transcranial Doppler device was used for simultaneous insonation of both middle cerebral arteries. The embolic signals were recorded after galactose (Echovist®) injection via the right antecubital vein during Valsalva maneuver. In case of a positive finding, the examination was repeated also at rest to discriminate large versus small shunts. Stroke or TIA were subtyped using the TOAST classification criteria. Results: Right-to-left shunting was detected in 255 (33.4%) patients. A positive finding was more common in patients with stroke of unknown origin compared with other subtype groups (43.3 vs. 28.2%, P<0.001). Mean age was smaller in PFO carriers (53.1 vs. 60.8 years, P<0.001). Multivariate analysis confirmed age and cryptogenic stroke to be independently associated with detectable PFO. Conclusions: Our findings confirm the previously proposed relationship between PFO and cryptogenic stroke in a large population of unselected stroke patients. Our findings suggest a causal connection rather than coincidence.