Co-Existing Subaortic Stenosis in a Patient With Hypertrophic Obstructive Cardiomyopathy: A Rare and Interesting Finding

Abstract

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disorder leading to left ventricular outflow tract (LVOT) obstruction. It can present with chest pain, syncope, breathlessness, or it may cause sudden cardiac death in some cases. The echocardiography in most cases while cardiac CT or cardiac MRI in selected cases are the important diagnostic modalities to make the diagnosis of HCM. In this case report, we discuss a case of a young female patient previously diagnosed with HCM and presented with palpitations, chest pain, and shortness of breath. Her echocardiography revealed severe asymmetrically hypertrophied left ventricle (LV) with normal function, the systolic anterior motion of the mitral valve was present and a subvalvular aortic membrane was also seen. The CT was also performed showing severe asymmetrical hypertrophied septum and thickened trileaflet tricommissural aortic valve with no calcification or significant valvular aortic stenosis but there was a subaortic membrane (concentric only sparing anteriorly). The presence of subaortic membrane with HCM is a rare finding and it can be a diagnostic challenge and untreated cases are susceptible to progressive heart failure and worsening of the symptoms by further increasing LVOT obstruction. A thorough investigation and planning before surgical intervention is required to achieve optimal results.

Imaging of left ventricular outflow tract obstruction in hypertrophic cardiomyopathy

“…Long-standing subaortic stenosis can result in LV hypertrophy which can be confused with HCM. A subaortic membrane has also been reported in previously documented cases of known HCM [28,29]. Mitral valve chordal rupture has been reported with a subaortic membrane, mimicking SAM seen in HCM and further confusing the diagnosis [30].…”