Case images: Absence of posterior mitral valve leaflet detected in late adulthood.

A 62-year-old woman suffering from dyspnea and palpitation was referred. Electrocardiography (ECG) revealed left bundle branch block and atrial fibrillation. Transthoracic echocardiography revealed absence of posterior mitral valve leaflet (PMVL) and mild mitral regurgitation (Figure A, Video 1*). Posterior myocardial wall replacement of the posterior leaflet had proceeded to coaptation line of the mitral valve (Figure B, Video 2*). Chordae tendineae and papillary muscles were attached to the tip of posterior myocardial wall. Coronary sinus was dilated. However, contrast echocardiography was normal during agitated saline injection into right and left upper extremity intravenous line. Ejection fraction was 40%, measured by Simpson’s rule. Subsequent transesophageal echocardiography (TEE) confirmed transthoracic echocardiography findings (Figure C; arrow: absent PMVL; Video 3*; all midesophageal views; 87°). Color Doppler examination revealed mild mitral regurgitation in TEE examination (Figure D). Coronary arteries were near normal on angiography. Medical follow-up was decided upon. Congenital malformations of the posterior mitral leaflet are extremely rare and present with a wide spectrum. Hypoplasia of the posterior mitral valve leaflet has been reported, and a few cases of absent PMVL have been described. Absence of the PMVL is usually symptomatic, due to severe mitral regurgitation and coexisting abnormalities such as intracardiac shunt. The present patient was asymptomatic until late adulthood, and no other cardiac anomaly was present. Absent PMVL may be more prevalent in asymptomatic adults than is known. 275