Morrow myectomy for obstructive hypertrophic cardiomyopathy in a patient with mitral valve prosthesis. A definitive resolution A case report.

Abstract

Introduction: Hypertrophic cardiomyopathy (HCM) is the most common type of cardiomyopathy and the leading cause of sudden cardiac death in young individuals. It is an autosomal dominant inherited disease with over 1,000 known mutations, most commonly affecting the β-myosin heavy chain. Sudden cardiac death, heart failure, and thromboembolic events are the significant causes of mortality in patients with HCM, with surgical intervention serving as a cornerstone of treatment.

Case Report: A 50-year-old man with a history of paroxysmal atrial fibrillation and mitral valve replacement with a mechanical prosthesis (severe mitral regurgitation) presented with a one-week history of palpitations and New York Heart Association (NYHA) class III dyspnea, with rapid progression of the functional class. Physical examination revealed a grade II/VI systolic murmur at the aortic area and a grade III/VI holosystolic murmur at the mitral area radiating to the axilla. Initial echocardiography demonstrated asymmetric septal hypertrophy (23 mm) with resting, and Valsalva-induced left ventricular outflow tract (LVOT) obstruction, with a pre-intervention gradient of 83 mmHg, and a severe eccentric perivalvular leak extending along the interatrial septum (Coanda effect) to the left atrial roof. Left ventricular ejection fraction was 62%, and diastolic function was restrictive. The heart team recommended surgical intervention.

Results: Septal myectomy significantly benefits the clinical course and survival of patients with obstructive HCM. In over 90% of cases, septal myectomy eliminates or significantly reduces the LVOT gradient. It improves exercise capacity and provides long-term benefits, with survival rates similar to those of the general population.