RESUMO
Patients with a prolapsing mitral leaflet frequently have chest pain while their coronary arteriograms are normal. In this regard, these patients are similar to the group of patients with angina and normal coronary arteriograms. In the present study, clinical, electrocardiographic, cardiac hemodynamic, angiographic, and metabolic findings in 20 patients with a prolapsing mitral leaflet were compared to those of 16 patients with angina and normal coronary arteriograms. Except for the presence of mitral leaflet prolapse and systolic clicks, the findings were similar in both groups. We postulate that prolapsing mitral leaflet is probably related to two different mechanisms. In one the primary pathologic change is in the mitral valve (mainly myxomatous transformation), and the abnormalities of ventricular contraction are secondary to unloading of the heart because of a volume shift into the distended and enlarged mitral leaflets. In the other group, the primary pathologic change is in the myocardium, with secondary prolapse of the mitral valve. The myocardial abnormality itself is probably related to primary underlying myocardial disease or to arteriolar pathologic changes. The latter group has probably the same pathophysiologic abnormality as patients with angina and normal coronary arteriograms.