Controversies in cardiovascular medicine. Most fully informed patients choose septal ablation over septal myectomy.

Hypertrophic cardiomyopathy (HCM) is a disease characterized by primary hypertrophy of the left (and sometimes right) ventricle. The clinical manifestations of the disease are dyspnea, angina, and a continuum encompassing lightheadedness, presyncope, syncope, and sudden death. Although HCM often is caused by an identifiable mutation in a gene coding for a sarcomeric protein and inherited in an autosomal-dominant pattern, many patients do not have any relatives in whom the disease is manifest. The prevalence of HCM is estimated to be 0.2%, with ≈600 000 Americans affected. Response by Maron p 216 Several anatomic variants of HCM exist. Of these, hypertrophic obstructive cardiomyopathy (HOCM) is the variant that has been the subject of the most intense investigation. HOCM was previously termed idiopathic hypertrophic subaortic stenosis and is characterized by 4 closely related pathoanatomic features (Figure 1).1 Obstruction to left ventricular (LV) outflow is caused by bulging of the thickened septum into the left ventricular outflow tract (LVOT) during systole, with apposition of the anterior (occasionally posterior) leaflet of the mitral valve, which demonstrates systolic anterior motion. Mitral regurgitation usually is present, although the degree varies greatly among patients with HOCM. LVOT gradients may be present at rest or only during Valsalva maneuver or exercise (provocable obstruction). A recent report suggests that if patients with provocable gradients are included, most patients with HCM have the obstructive form of the disease.2 Figure 1. Schematic depiction of 4 elements of the pathoanatomy of HOCM showing asymmetric septal hypertrophy (ASH), systolic anterior motion (SAM) of the anterior leaflet of the mitral valve, an LVOT gradient, and mitral regurgitation (MR). LA indicates left atrium. Reprinted from Fifer.1 The management of HCM may be considered as consisting of 4 elements (Table 1).3 For patients at high risk of sudden death, implantation …