The Role of Risk Factors and Trigger Factors in Cerebrovascular Events After Mitral Valve Replacement: Implications for Antithrombotic Management

To determine the effect of risk factors and trigger factors on cerebrovascular events, 622 patients who survived mitral valve replacement between December 1979 and December 1992 were analyzed. Ninety-six patients suffered 139 nonhemorrhagic cerebrovascular events. Data were available on 138 events in 95 patients. There were 32 transient ischemic attacks (TIAs), 57 reversible ischemic neurological deficits (RINDs), and 49 strokes. Age, sex, atrial fibrillation, left atrial size, systemic hypertension, and abnormal body mass index did not discriminate between patients who suffered events and those who did not. In contrast, smoking status differed significantly between patients who suffered events and those who did not. Among current or recent ex-smokers, the risk of stroke or RIND was significantly higher than in non-smokers (p < < 0.001). The odds ratio of suffering any type of event in patients who smoked at any time postoperatively versus those who did not smoke was 2.9 (95% confidence interval: 1.8 to 4.6). Of 61 patients contacted directly, 30% recalled an infective episode immediately prior to their event. A diurnal and seasonal influence on events was also detected with peaks in the morning and in the winter months, respectively (both p < 0.001). It is concluded that there is persuasive evidence for the involvement of several nonprosthetic factors in the incidence of cerebrovascular events after mitral valve replacement. This has implications for patient management and for future analysis of prosthetic heart valve series.