Effectiveness of Alcohol Septal Ablation Versus Transaortic Extended Myectomy in Hypertrophic Cardiomyopathy with Midventricular Obstruction

OBJECTIVES: Investigate the effectiveness of alcohol septal ablation (ASA) and transaortic extended myectomy (TEM) in hypertrophic cardiomyopathy (HCM) with midventricular obstruction (MVO). BACKGROUND: MVO is less common than subaortic obstruction. Data on the effectiveness of ASA and TEM in MVO are lacking. METHODS: The clinical profiles of 22 patients undergoing ASA and 37 patients undergoing TEM were compared. No patient had apical aneurysm, abnormal chordae, mitral valve replacement or repair. RESULTS: Baseline midventricular pressure gradient and symptoms were comparable between the ASA and TEM groups. During follow-up, both groups demonstrated substantial reduction in pressure gradient (the ASA group: 79.7 ± 21.2 mm Hg to 43.7 ± 28.9 mm Hg, P < 0.001; the TEM group: 69.0 ± 23.9 mm Hg to 15.0 ± 16.9 mm Hg, P < 0.001). The reduction in pressure gradient was greater (78.9 ± 18.6% vs. 46.4 ± 33.4%, P < 0.001) and the residual pressure gradient was lower after TEM versus ASA (P < 0.001). Patients with New York Heart Association class III/IV dyspnea decreased from 59.1 to 18.2% (P = 0.022) in the ASA group and from 56.8 to 5.6% (P < 0.001) in the TEM group. Patients with Canadian Cardiovascular Society class III/IV angina decreased from 40.9 to 9.1% (P = 0.016) in the ASA group and from 32.4 to 0% (P < 0.001) in the TEM group. CONCLUSIONS: While ASA and TEM both improve gradients and symptoms, TEM may provide a more reliable reduction in gradients compared to ASA.