Heart Murmur and Cardiomegaly in a Young Man

A 38-year-old man was seen for evaluation of a heart murmur. Left ventricular prominence was seen on a chest film; the ECG suggested left ventricular hypertrophy. A left ventricular-mitral valve echocardiogram is shown in the Figure below with a superimposed high-frequency second left intercostal space phonocardiogram. What is your diagnosis? Cardiac catheterization confirmed this diagnosis and demonstrated moderate severity. The echocardiogram was taken of the left ventricle at the level of the mitral valve. As shown in the Figure, the ECG (lead II) is at the top of the echocardiogram. A high-frequency phonocardiogram was taken at the second left intercostal space. A loud aortic component of the second sound (S2) is followed by a high-frequency decrescendo diastolic murmur of aortic regurgitation. The first sound (S2) is diminished at the second left intercostal space. The posterior left ventricular wall motion is anterior during systole. The anterior mitral