Subaortic Membrane With Mitral Chordae Rupture Mimicking Left Ventricular Outflow Tract Obstruction in Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is an autosomal-dominant disorder that can lead to left ventricular outflow tract (LVOT) obstruction. Some patients present with syncope, dyspnea, chest pain, or sudden cardiac death. A subaortic membrane (SAM) is an unusual cause of ventricular outflow tract obstruction causing symptoms that can imitate HCM. It is essential to differentiate between these two entities, as it has important implications in guiding treatment and determining the type of intervention. Echocardiography is the gold standard modality for the diagnosis. In this report, we present a case of a 56-year-old man presenting with subaortic stenosis with ruptured mitral chordae misdiagnosed as HCM with SAM.