Microvascular dysfunction causing myocardial ischemia in obstructive hypertrophic cardiomyopathy

Abstract

Hypertrophic cardiomyopathy (HCM) is characterized by myocardial hypertrophy and can lead to significant complications including left ventricular outflow tract obstruction (LVOTO) and myocardial ischemia. Microvascular dysfunction (MVD) is a less recognized but crucial cause of myocardial ischemia in HCM, contributing to myocardial injury in the absence of obstructive coronary artery disease. We presented a case of a 48-year-old male with retrosternal chest tightness radiating to the left arm for 3 h. Electrocardiography revealed left ventricular (LV) hypertrophy with ST-segment depression and T wave inversion. High-sensitivity troponin T levels were elevated. Echocardiography showed marked LV wall thickness, predominantly at the basal septum, with systolic anterior motion of anterior mitral valve leaflet causing LVOTO. Adenosine stress cardiac magnetic resonance imaging demonstrated faint patchy scars in the hypertrophied ventricular septum and significant stress-induced perfusion defects beyond the area of myocardial scarring. Coronary angiography showed normal epicardial arteries, suggesting MVD as the underlying cause of ischemia. The patient was treated with nebivolol and verapamil, leading to symptom relief and a reduction in the pressure gradient of LVOTO at follow-up. This case highlights the role of MVD in causing myocardial ischemia in patients with HCM. Effective management of HCM with MVD includes pharmacological therapy to alleviate outflow obstruction and improve myocardial perfusion. Comprehensive diagnostic and treatment approaches are essential for optimizing outcomes in patients with this complex condition.