Recurrent Cerebrovascular Events
March 1, 2002
Recurrent Cerebrovascular Events
Abstracts & Commentary
Sources: Mas JL, et al. Recurrent cerebrovascular events associated with patent foramen ovale, atrial septal aneurysm, or both. N Engl J Med. 2001;345:1740-1746; Meier B. Patent foramen ovale—beauty spot or health threat? Cardiology Rounds. 2001;5:1-8 (www.cardiologyrounds.org).
Results of transesophageal echocardiography (TEE) during recent years have identified a high prevalence of cardiac abnormalities in the general population. In one study of randomly selected subjects aged 45 years or older, TEE detected patent foramen ovale (PFO) in 26% and atrial septal aneurysm (ASA) in 2%. In patients with a cryptogenic stroke, associated rates of detection of PFO range from 31-77% and for ASA from 4-25% (Neurology. 2000;55:1865-1867).
In a prospective multicenter study, Mas and colleagues enrolled 581 patients, aged 18-55 years, who had suffered a cryptogenic ischemic stroke within the preceding 3 months. All received aspirin 300 mg daily for secondary stroke prevention. All patients underwent transthoracic echo cardiography and TEE. Patients were assessed for PFO and ASA at rest and during valsalva maneuver and coughing.
After 4 years, the risk of recurrent stroke was 2% among patients with PFO alone, 15% among patients with both PFO and ASA, 8%, and 4% among patients who had neither of these cardiac abnormalities. No recurrences affected the patients with ASA alone. The presence of both PFO and ASA was a significant predictor of an increased risk of recurrent stroke (hazard ratio, 4.17; 95% confidence interval, 1.47-11.84). The presence of isolated PFO, whether small or large, was not a significant risk factor for recurrence.
In an encyclopedic review, Bernhard Meier has summarized the etiology of PFO, diagnostic methods for PFO and the relationship between PFO and stroke, as well as methods of closure, emphasizing percutaneous transcatheter closure.
Commentary
An ASA is 10 times less common than a PFO. It previously has been identified in the Stroke Prevention Assessment of Risk in a Community (SPARC) Study (Mayo Clin Proc. 1999;74:862-869) as a risk enhancer in the presence of PFO, rather than an independent source of embolism. Mas et al have confirmed that finding.
Mas et al did not confirm that the size of the PFO or the degree of shunting was a significant predictor of the risk of recurrent TIA or stroke. In a previous study, Homma and colleagues reported that the size of a PFO and the number of bubbles passing through were significant risk factors for stroke (Stroke. 1994;25:582-586).
In view of the low risk of recurrent stroke in PFO patients treated medically with aspirin or warfarin, the role of surgical or percutaneous transcatheter closure of a PFO remains uncertain. Nevertheless, percutaneous close of a PFO seems promising and should be considered in patients with recurrent emboli on medical treatment, with an ASA, or a tendency for venous thrombosis. —John J. Caronna.
Caronna, MD, Vice-Chairman, Department of Neurology, Cornell University Medical Center; Professor of Clinical Neurology, New York Hospital, is Associate Editor of Neurology Alert.
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