Increased left ventricular mass in idiopathic mitral valve prolapse.

We performed M-mode echocardiography on 100 subjects with idiopathic mitral valve prolapse (IMVP) and on 100 normal control subjects to determine if differences exist between the two groups in cardiac chamber size, left ventricular performance or left ventricular mass. Subjects with IMVP demonstrated significantly greater left ventricular mass than normal control subjects. There were no significant differences in fractional shortening of the left ventricle or left ventricular end-diastolic volume. There was no significant difference in left ventricular mass between asymptomatic subjects with IMVP and those with chest pain, palpitations, syncope or presyncope. Subjects with and without mitral regurgitation showed no significant difference in mass. The results indicate that subjects with IMVP demonstrate subtle left ventricular hypertrophy which does not appear to be caused by underlying organic heart disease, mitral regurgitation or sustained hypercontractility. This suggests that myocardial involvement is an integral part of the IMVP syndrome.