Patent Foramen Ovale, Subclinical Cerebrovascular Disease and Ischemic Stroke in a Population-Based Cohort

Study Questions:

What is the relationship between patent foramen ovale (PFO) and ischemic stroke and cerebrovascular disease in the general population?

Methods:

A sample of 1,100 stroke-free individuals ages 39 and older was followed for a mean of 11 years. PFO was diagnosed using transthoracic echocardiogram with saline contrast injection. A subcohort of 360 subjects underwent brain magnetic resonance imaging (MRI) for detection of silent brain infarct (SBI).

Results:

The mean age was 68.7 ± 10.1 years. A PFO was present in 164 (14.9%) participants. Over the follow-up period (mean 11.0 ± 4.5 years), 111 (10.1%) ischemic strokes occurred in the entire cohort. Ischemic stroke occurred in 15 (9.2%) patients with PFO and 96 (10.3%) patients without PFO. The 12.5-year cumulative stroke risk was 10.1% (standard error 2.5%) in participants with PFO and 10.4% (standard error 1.1%) in participants without PFO. The adjusted hazard ratio for PFO and stroke was 1.10 (95% confidence interval, 0.64-1.91). For subjects in the MRI cohort, PFO was not associated with SBI (adjusted odds ratio, 1.15; 95% confidence interval, 0.50-2.62).

Conclusions:

The authors concluded that in a community-based cohort, PFO was not associated with an increased risk of clinical stroke or subclinical cerebrovascular disease.

Perspective:

This important study investigated the relationship between PFO and stroke in the general population. While previous case-control studies have demonstrated a relationship between PFO and stroke, this prospective study showed no association between PFO and either clinical stroke or subclinical cerebrovascular disease. This study will provide reassurance to clinicians and patients regarding the incidental finding of PFO, and affirms that there does not appear to be a role for therapies directed at primary prevention of stroke. The age of the patient population was relatively advanced (mean age almost 69 years), and the prevalence of PFO was somewhat smaller than reported in some studies at 14.9%. This may have been due to the use of transthoracic echocardiography for diagnosis of PFO. This study should not impact secondary prevention strategies for patients with previous stroke, as they have self-selected themselves into a high-risk group and therefore cannot be compared with the general population. Importantly, although several high-risk features of PFO have been put forth (size, presence of atrial septal aneurysm), further investigation will be required to prospectively identify individuals with PFO at risk for ischemic stroke.

Clinical Topics: Congenital Heart Disease and Pediatric Cardiology, Noninvasive Imaging, Prevention, Congenital Heart Disease, CHD & Pediatrics and Arrhythmias, CHD & Pediatrics and Imaging, CHD & Pediatrics and Quality Improvement, Echocardiography/Ultrasound, Magnetic Resonance Imaging

Keywords: Odds Ratio, Risk, Stroke, Follow-Up Studies, Ischemic Attack, Transient, Heart Defects, Congenital, Foramen Ovale, Patent, Magnetic Resonance Imaging, Primary Prevention, Prevalence, Case-Control Studies, Secondary Prevention, Cerebrovascular Disorders, Brain Infarction, Confidence Intervals, Echocardiography, Incidental Findings


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