Abstract 14301: Effects of Septal Reduction Therapy on Acute Cardiovascular Events and All-cause Mortality in Patients With Obstructive Hypertrophic Cardiomyopathy: Propensity Score-matched Study

Introduction: Septal reduction therapy (SRT) - i.e., septal myectomy and alcohol septal ablation - has been used to treat medically-refractory obstructive hypertrophic cardiomyopathy (HOCM) for a few decades. However, the effects of SRT on the risk of acute cardiovascular (CV) events and all-cause mortality are largely unknown. Hypothesis: SRT is associated with a long-term decrease in acute CV events and a short-term increase in all-cause mortality in patients with HOCM. Methods: We performed a propensity score (PS)-matched study using all-payer databases that capture all hospitalizations and outpatient visits in New York State. We identified patients with HOCM who underwent SRT between January 1, 2007 and December 31, 2014 (i.e., the SRT group) and those who have never had SRT but had at least one hospitalization for HOCM during the same period (i.e., the control group). We performed 1:1 PS matching using age, sex, race/ethnicity, source of payment, season and year of starting event follow-up (i.e., the day of SRT or the index hospitalization), and Elixhauser comorbidity measures. The primary outcomes were (1) acute CV event (i.e., emergency department visit or unplanned hospitalization for CV disease) during 1-360 days and 361-720 days and (2) 7-, 15-, 30-, 180-, and 360-day all-cause mortality. We compared the risk of the outcome event using logistic regression models. Results: The analytic cohort consisted of 690 patients with HOCM (i.e., 345 PS-matched pairs). The SRT group had a lower risk of acute CV event during 361-720 days (OR 0.44; 95% CI, 0.20-0.97; P=0.04) but a higher risk of 7-day mortality (11 vs. 2 in the control group; P=0.03). The SRT group had a non-significant trend towards lower all-cause mortality in longer terms ( Figure ). Conclusion: In this population-based PS-matched study of patients with HOCM, SRT was associated with a reduced risk of acute CV events in the second post-procedure year at the sacrifice of a short-term increase in all-cause mortality.