Mitral valve prolapse and infective endocarditis

This study describes the clinical features, laboratory findings and follow-up of 25 patients with bacterial endocarditis found to have mitral valve prolapse. Mitral valve prolapse was confirmed by echocardiography (17 patients), angiocardiography (nine patients) or by pathologic study of the mitral valve (10 patients). There were no associated cardiac lesions except for atrial septal defect in two patients. Physical examination at the time of endocarditis revealed holosystolic murmurs in 22 patients (five with late systolic crescendo) and mid-systolic click with late systolic murmur in three. Six patients with holosystolic murmurs were known to have had only late systolic murmurs prior to endocarditis. Causative organisms included alpha Streptococcus in 12 patients, Strep. group D in five, Staphylococcal aureus in four, and Strep. hemolyticus, Bacteroides, Hemophilus aphrophilus, Strep. pneumoniae and Moraxella in one patient each. Nine patients, six of whom had ruptured chordae tendineae, subsequently required mitral valve replacement. In two additional patients congestive heart failure developed which responded to medical therapy. Cerebral embolism occurred in five patients. Three patients had second episodes of endocarditis. One death occurred from cerebral hemorrhage secondary to thrombocytopenia. Ten of these 25 patients were found in a review of 87 consecutive patients with infective endocarditis seen over a five-year period at Stanford University Hospital. Twenty-eight of the 87 had isolated mitral regurgitation, suggesting that mitral valve prolapse is the basis for about one third (10 of 28) of the instances of bacterial endocarditis associated with isolated mitral regurgitation in our hospital. The high incidence of holosystolic murmurs suggests either that endocarditis leads to more severe mitral regurgitation and ruptured chordae in some instances or that patients with holosystolic murmurs are more susceptible to bacterial endocarditis than those with less striking auscultatory findings.