Abstract 3807: Outcomes of Septal Myectomy and Alcohol Septal Ablation for Obstructive Hypertrophic Cardiomyopathy: The Stanford Experience
Background: The presence of left ventricular outflow tract (LVOT) obstruction predicts increased mortality in hypertrophic cardiomyopathy (HCM). Myectomy and alcohol septal ablation (ASA) aim to decrease LVOT gradient. The impact of such septal reduction therapies on survival requires elucidation.
Method: In this nonrandomized retrospective study, we present data from 171 patients who underwent myectomy and 52 patients who underwent ASA for symptomatic LVOT obstruction between 1971 and 2006 at a single tertiary hospital. Follow-up of NYHA functional class, echocardiographic data, and vital status was obtained from patient records, mailed questionnaires, and Social Security Death Index. Mortality rates were compared with expected mortality rates of age- and gender-matched population using the U.S. Census Bureau 2002 national life tables by means of a 1-sample log-rank test.
Results: The ASA cohort was older (57.3±12.9 vs 48.0±17.1) and more likely to be male (56% vs 49.1%) than the myectomy cohort. Both ASA and myectomy improved NYHA class (2.99±0.35 to 1.5±0.74 for ASA, p<0.001; 2.74±0.65 to 1.54±0.74 for myectomy, p <0.001) and reduced resting (67.1±26.9 to 23.9±29.4 mm Hg for ASA, p<0.001; 67.4±43.4 to 11.2±16.4 mm Hg for myectomy, p<0.001) and provoked LVOT gradients (104.4±34.9 to 35.5±38.6 mm Hg for ASA, p<0.001; 98.1±34.7 to 33.6±34.9 mm Hg for myectomy, p<0.001). 30 day mortality was low (0% for ASA, 2.9% for myectomy). Survival after ASA at 5 and 7 years was 92.3 and 92.3%, respectively. Survival after myectomy at 5, 7, 10, 20, 30, and 36 years was 94.1, 88.1, 80.8, 57.9, 50.0, and 50.0%, respectively. Short term (7-year) survival after ASA (standardized mortality ratio [SMR]= 1.60, p=0.35) was comparable to that of the general population. Long term survival (36-year) after myectomy was lower than for general population (SMR=1.97, p<0.001) but still compared favorably with historical data from non-operated HCM patients.
Conclusion: Myectomy and ASA are safe and effective for symptom relief and LVOT gradient reduction and are associated with favorable short term survival. However, longer follow-up is needed for ASA, and further investigation into the determinants of the still suboptimal long term prognosis after myectomy is warranted.