Hypertrophic Cardiomyopathy with Absent Major Septal Perforator Coronary Artery Successfully Treated With Dual-Chamber Pacing as an Alternate Strategy to Septal Reduction Therapy: A Case Report

Abstract

The most important hemodynamic consequence of hypertrophic cardiomyopathy (HCM) is left ventricular outflow tract (LVOT) obstruction. Its primary management is surgical myectomy, but an alternative treatment is alcohol septal ablation (ASA). However, in patients with unfavorable coronary anatomy that precludes ASA (i.e., absent major septal perforator artery), another option is dual-chamber pacemaker implantation to relieve the LVOT obstruction. Case: A 77-year-old Filipino female presented with one week’s history of chest pain and dyspnea. On work-up, 2D-echocardiography revealed HCM with systolic anterior motion (SAM) of the mitral valve, with a peak instantaneous gradient of 194 mmHg across the basal left ventricular cavity. The patient refused myectomy; ASA was the preferred treatment option. However, coronary angiography revealed incidental absence of major septal perforator artery, which made the patient unsuitable for ASA. As an alternate strategy, a dual-chamber pacemaker was inserted. This resulted in a significant decrease in peak instantaneous gradient (from 194 mmHg to 37 mmHg), the obliteration of systolic anterior motion and improvement in overall wall motion. She was asymptomatic and stable after pacemaker insertion and remained asymptomatic on follow-up after five months. Conclusion: We present a case of HCM with congenitally absent major septal perforator coronary artery, treated with dual-chamber pacemaker. To our knowledge, this is the first reported local experience of an angiographically absent major septal perforator coronary anatomy in the setting of HCM and also the first description of dual-chamber pacemaker implantation done to successfully relieve LVOT obstruction. Although the role of dual-chamber pacing has become limited in HCM because septal reduction therapy has resulted in improved symptoms and decrease in LVOT gradient, this cardiac pacing remains essential and may be considered the treatment of choice in patients who are unsuitable for surgical myectomy and ASA. KEYWORDS: hypertrophic cardiomyopathy, hypertrophic obstructive cardiomyopathy, HCM, HOCM, surgical myectomy, alcohol septal ablation, dual chamber pacemaker implantation