[Clinicopathologic study of mitral regurgitation due to abnormal chordae tendineae]

Severe mitral regurgitation (MR) due to abnormal chordae tendineae as a primary cause is rare. This clinicopathologic study included four such cases which occurred among 6,500 consecutive autopsies on persons older than 60 years. This paper describes three of these cases. Case 1 was a 76-year-old woman with congestive heart failure, MR and atrial fibrillation. She died of acute myocardial infarction. The heart weighed 360 g. Mitral regurgitation was caused by a thick and long abnormal chorda originating from the posteromedial papillary muscle and protruding into the atrial surface of the middle scallop of the posterior mitral leaflet associated with prolapsed anterior mitral leaflet. Case 2 was an 81-year-old woman with MR and congestive heart failure. She died of acute myocardial infarction. The heart weighed 480 g. There were abnormal chordae tendineae with very few branches at the posterior commissure. Parts of both mitral leaflets on the sides of posterior commissure were also prolapsed. Case 3 was a 91-year-old man with MR and atrial fibrillation. He died of congestive heart failure. The heart weighed 530 g. Abnormal chordae tendineae with reticular structures originated from the anterolateral papillary muscle and protruded into the anterior mitral leaflet, which induced severe MR. These cases had abnormally protruding chordae tendineae, abnormal branching, and abnormal structures of the chordae tendineae, respectively. These abnormal chordae tendineae were considered to be congenital anomalies. Clinically all patients had a holosystolic murmur (Levine III-IV degrees), refractory congestive heart failure and atrial fibrillation. The etiology of the MR in these three patients was suspected to be ruptured chordae tendineae demonstrated on echocardiograms. These patients had heavy hearts (mean 457 g) with enlarged left atria and thickened mitral valves, which corresponded to the appearance of severe MR.