The association between the diameter of a patent foramen ovale and the risk of embolic cerebrovascular events

PURPOSE: We sought to determine whether the size of a patent foramen ovale affected the risk of embolic cerebrovascular events of unknown origin. PATIENTS AND METHODS: We ascertained the presence and measured the size of patent foramen ovale using multiplane transesophageal echocardiography in 121 consecutive patients younger than 60 years who had transient ischemic attacks or ischemic strokes and in 123 control subjects. None of the patients had left heart, aortic, or carotid sources of embolism, or echocardiographic signs of elevated left or right atrial pressure. We used multivariate logistic regression to determine whether the size of the patent foramen ovale was an independent risk factor for cerebrovascular events. RESULTS: The mean (± SD) diameter of a patent foramen ovale was significantly larger in patients (4 ± 2 mm) than in control subjects (2 ± 1 mm, P<0.0001). A patent foramen ovale greater than 4 mm was associated with an increased risk of transient ischemic attacks [odds ratio (OR) = 3.4; 95% confidence interval (CI), 1.0 to 11, P = 0.04], ischemic strokes (OR = 12; 95% CI, 3.3 to 44, P = 0.0001), and, especially, having evidence of two or more strokes (OR = 27; 95% CI, 4.7 to 160, P = 0.0002). CONCLUSION: The diameter of a patent foramen ovale is an independent risk factor for ischemic events, especially recurrent strokes.