Patent foramen ovale as a risk factor for cryptogenic stroke.

OBJECTIVE

To determine and compare the prevalence of patent foramen ovale in patients with stroke of undetermined origin (cryptogenic) and in patients with stroke of determined origin to assess the possible role of patent foramen ovale as a risk factor for cryptogenic stroke.

DESIGN

Cross-sectional study with nested case-control analysis.

PATIENTS

A total of 146 patients (73 men, 73 women) with acute ischemic stroke referred to the echocardiography laboratory for evaluation.

SETTING

Neurovascular Unit and Echocardiography Laboratory, Columbia-Presbyterian Medical Center, New York, New York.

MEASUREMENTS

Patients were considered to have strokes of determined origin or cryptogenic strokes according to National Institute of Neurological Disorders and Stroke (NINDS) Stroke Data Bank criteria. The presence of patent foramen ovale was assessed by contrast echocardiography, performed blinded for type of stroke. The association between patent foramen ovale and type of stroke was tested after correcting for patients' demographic variables and stroke risk factors.

RESULTS

The overall prevalence of patent foramen ovale was 26 of 146 patients (18%; 95% Cl, 11.4% to 24.6%). Patients with cryptogenic stroke (31%) had a significantly higher prevalence of patent foramen ovale than did patients with an identifiable cause of stroke (69%) in both the younger (less than 55 years; 48% compared with 4%; P less than 0.001) and the older (greater than or equal to 55 years; 38% compared with 8%; P less than 0.001) age groups. Multiple logistic regression analysis was used to identify the presence of a patent foramen ovale as strongly associated with the diagnosis of cryptogenic stroke (odds ratio, 7.2; Cl, 2.4 to 21.7), irrespective of patient age and other stroke risk factors.

CONCLUSIONS

Patients with cryptogenic stroke have a higher prevalence of patent foramen ovale than patients with stroke of determined cause in all age groups, even after correcting for the presence of recognized stroke risk factors. This identifies patent foramen ovale as a risk factor for cryptogenic stroke. Regardless of patient age, contrast echocardiography should be considered when the cause of stroke is unknown.