The Return of Mitral Valve Prolapse as a Cause of Stroke

Abstracts & Commentary

Sources: Avierinos JF, et al. Cerebral ischemic events after diagnosis of mitral valve prolapse. A community-based study of incidence and predictive factors. Stroke. 2003;34:1339-1344; Oppenheimer S. Editorial comment. Is MVP an MVP in ischemic cerebral events? Stroke. 2003;34:1345.

The relationship between mitral valve prolapse (MVP) and ischemic neurological events remains controversial. Barnett and colleagues first reported the association between stroke and mitral valve prolapse mainly in young patients.1 Subsequent publications could not identify any increased risk of cerebral embolism in patients with MVP,2 and the condition ceased to be considered a major risk factor for stroke. Indeed, it has come to be considered a harmless variant that is common in the general population. Avierinos and colleagues at the Mayo Clinic have used the Olmstead County, Minn, Data Base to study the association between MVP and ischemic neurological events. They identified MVP patients diagnosed between 1989 and 1998. Patients were selected for echocardiography on the basis of auscultation findings (70%). The remaining 30% had cardiorespiratory or other symptoms that were reasons for echocardiography. The inclusion criteria were that the patients had no evidence of atrial fibrillation on ECG and no previous cardiac surgery or history of stroke or TIA. There were 777 eligible subjects. Their mean age was 49 ± 20 years, and 66% were women. The follow-up period averaged 5.5 years. Thirty patients (14 men, 16 women) experienced a first ischemic neurological event (12 TIAs, 18 cerebral infarctions). Seven of those patients had recurrent ischemic neurologic events during the follow-up period. Twenty-eight symptomatic patients had carotid Doppler examinations. Only 2 patients, both of whom suffered cerebral infarcts, had ipsilateral cerebrovascular stenosis. Only 1 ischemic event, a TIA, occurred in a patient younger than 50 at diagnosis. Ischemic neurologic events occurred in 20 patients undergoing medical management and in 10 patients only after they had had cardiac surgery. Nine of these 10 patients had severe mitral regurgitation. In 16 patients, the first ischemic neurological event occurred after atrial fibrillation had been diagnosed, and in 14 patients, the first ischemic neurological event occurred without detected atrial fibrillation and under conservative management.

Compared with expected neurological events in the same community, subjects with mitral valve prolapse showed an excess risk of lifetime ischemic events (relative risk, 2.2; P < .001). The excess risk of TIA and stroke was observed in the high-risk subsets of patients undergoing medical management. These high-risk subsets included those with advancing age and thickened mitral leaflets at diagnosis. Subsequently, the need for cardiac surgery and the occurrence of atrial fibrillation in the course of the disease were independently associated with the risk of ischemic neurologic complications. The time-dependent risk factors or excess rates of ischemic neurologic events were related to the degree of mitral regurgitation resulting from MVP. In these patients, the subsequent need for cardiac surgery and the occurrence of atrial fibrillation in the course of the disease were independently associated with the risk of ischemic neurologic complications.

Avierinos et al conclude that the high-risk subgroups of MVP patients, namely those who are older and have mitral regurgitation, atrial fibrillation, and an enlarged left atrial diameter, require careful monitoring and therapeutic interventions to minimize the risk of stroke.

Commentary

As noted by Oppenheimer in his editorial comment on this paper, this is a valuable study that helps to identify mitral valve patients at high risk of cerebral vascular events. The prognostic indicators for a high risk of stroke or TIA were older age (older than 50 years, atrial fibrillation, mitral valve thickening, and mitral regurgitation requiring cardiac surgery). It may be that older age is a marker for the fact that MVP in those patients is ischemic rather than congenital. Atrial fibrillation and an enlarged atrial dimension also are factors that are implicated in cardiogenic stroke apart from the presence of mitral valve prolapse. In the same way, cardiac surgery involving valve repair is an independent risk factor for stroke unrelated to MVP. Although the study makes no recommendations for treatment, clinicians must decide for themselves whether anticoagulation should be instituted in the higher-risk group, notably those older than 50 with atrial fibrillation, mitral valve thickening, or a previous history of stroke or TIA. In patients with mitral valve prolapse and an ischemic neurological event, there was a high recurrence rate that was 27% over the follow-up period. In contrast, patients younger than 50 without any of the high-risk factors probably do not need any prophylactic treatment to prevent stroke because their incidence of cerebral embolism was extremely low. Further studies of MVP patients in the high-risk categories will be required to determine the effect of medical intervention, namely antiplatelet or anticoagulant drugs on prognosis. — John J. Caronna, MD. Dr. Caronna, Vice-Chairman, Department of Neurology, Cornell University Medical Center; Professor of Clinical Neurology, New York Hospital, is Associate Editor of Neurology Alert.

References

1. Barnett HJ, et al. Arch Neurol. 1976;33:777-782.

2. Gilon D, et al. N Engl J Med. 1999;341:8-13.