The case is reported of a patient with a previously undiagnosed cause of severe congestive heart failure (CHF) caused by the presence of a discrete subaortic stenosis (SAS) from a subvalvular membrane (SVM). The clinical decision making was complicated by the concurrent presence of systolic anterior motion (SAM) of the mitral valve leaflet. Due to the limitations and eventual failure of physiologically opposing medical management strategies, the patient eventually required an open-heart surgical approach and underwent intraoperative SVM resection. A persistent intraoperative left ventricular outflow tract (LVOT) gradient of 50 mmHg due to SAM prompted mitral valve replacement, which resulted in a complete resolution of the LVOT gradient and symptoms. In this extremely rare scenario of SAS and SAM, when SVM resection is thought to be inadequate to relieve LVOT obstruction due to the concurrent presence of SAM, mitral valve replacement represents a reasonable therapeutic approach.