RISK OF STROKE WITH MITRAL-VALVE PROLAPSE IN POPULATION-BASED COHORT STUDY

Background and Purpose The purpose of this study was to clarify whethe r mitral valve prolapse increases the subsequent risk of stroke. Metho ds A historical cohort study was conducted on 1079 residents of Olmste d County, Minnesota, who had an initial echocardiographic diagnosis of mitral valve prolapse between 1975 and 1989 without prior stroke or t ransient ischemic attack and who were followed up for first stroke occ urrence. Results There was an overall twofold increase in the incidenc e of stroke among individuals with mitral valve prolapse relative to t he reference population (standardized morbidity ratio, 2.1; 95% confid ence interval, 1.3 to 3.2). Sex, duration of follow-up from the diagno sis of mitral valve prolapse, or calendar year of initial diagnosis di d not modify the association. Within the cohort of patients who were a t least 35 years old at diagnosis of mitral valve prolapse, a time-dep endent proportional-hazards multivariate model and a person-years anal ysis revealed that age, ischemic heart disease, congestive heart failu re, and diabetes mellitus were important determinants for stroke when person-years of observation after mitral valve replacement were exclud ed. Among seven persons with mitral valve replacement, three strokes o ccurred in 24 person-years of follow-up. For those with an auscultator y diagnosis of mitral valve prolapse only as the indication for echoca rdiography (44%), the risk of stroke relative to the population was 1. 0 (95% confidence interval, 0.2 to 2.9); for those with another cardia c diagnosis, the standardized morbidity ratio was 2.5 (95% confidence interval, 1.5 to 4.0). Conclusions Individuals with uncomplicated mitr al valve prolapse did not have an increased risk of stroke, although a small increase in the risk may not have been detected.