Long-term outcomes after septal reduction therapy for obstructive hypertrophic cardiomyopathy: a nationwide cohort study

Abstract Aims With cardiac myosin inhibitors emerging as a novel pharmacological option instead of septal reduction therapies (SRT) in obstructive hypertrophic cardiomyopathy (HCM), contemporary data on national long-term outcomes after SRT are needed. Methods In this nationwide cohort study from 2015 to 2021, patients with obstructive HCM undergoing SRT (surgical myectomy or transcoronary ablation of septal hypertrophy) were 1:8 propensity score-matched with nonobstructive HCM patients or surgical controls undergoing appendectomy without heart disease in recent records. As assessed in time-to-event analyses, the primary outcome was a composite of all-cause mortality after discharge and rehospitalization for heart failure. Results After matching, 125 patients with obstructive HCM hospitalized for SRT were compared to 743 patients hospitalized with nonobstructive HCM. The incidence rate (IR) of the primary outcome was lower in the SRT group (12.62 versus 74.86 per 1,000 patient-years (py); hazard ratio (HR), 0.17 (95% confidence interval [CI], 0.07 to 0.42); median follow-up 31 months). In the second comparison, 126 patients with obstructive HCM undergoing SRT were matched to 560 surgical controls without heart disease undergoing laparoscopic appendectomy. The IR of the primary outcome after SRT was comparable to that of surgical controls without heart disease (12.61 versus 8.09 per 1,000 py; HR, 1.53 (95% CI, 0.56 to 4.18); median follow-up 41 months). Conclusion In this nationwide cohort study, SRT was associated with a lower incidence of all-cause mortality after discharge and rehospitalization for heart failure compared to patients hospitalized with nonobstructive HCM, with an incidence comparable to surgical controls without heart disease.