Reoperation for acquired discrete subaortic membrane and multivalvular dysfunction after mitral valve replacement.

A 57-year-old female patient presented to our outpatient clinic with complaints of anginal chest pain. She had a history of mitral commissurotomy and later mechanical mitral valve replacement via a robotic surgical approach due to rheumatic heart disease. On physical examination, a pansystolic murmur at the apex and an arrhythmic mechanical heart sound were noted. Transesophageal echocardiography (TEE) revealed severe tricuspid valve insufficiency, pulmonary hypertension, moderate to severe aortic stenosis, acquired discrete subaortic membrane (DSM), a paravalvular leak with mild insufficiency in the mechanical prosthetic mitral valve, and non-obstructive pannus on the left ventricular side. The patient underwent reoperation, including DSM resection, aortic and tricuspid valve replacement, and paravalvular leak repair. Postoperative recovery was uneventful. Acquired DSM following mitral valve replacement (MVR) is a rare but increasingly recognized entity. The underlying mechanism may involve postoperative hemodynamic alterations, excessive leaflet preservation, or residual fibrosis. Extended myectomy techniques may offer a more durable solution in selected cases, reducing the risk of recurrence and reoperation. Supplementary Information: The online version contains supplementary material available at 10.1007/s12055-025-01995-8.