Cardiovascular Hospitalizations Burden Following Septal Myectomy for Obstructive Hypertrophic Cardiomyopathy

Background Longer‐term morbidity post septal myectomy (SM) in obstructive hypertrophic cardiomyopathy has not been well characterized at a national level. We aimed to investigate the nonfatal longer‐term post‐SM outcomes from a national all‐payer individual‐level claims. Methods The Symphony Health Claims database (2016–2021) was analyzed to identify all adult patients with obstructive hypertrophic cardiomyopathy who underwent SM in the United States and had at least 1 claim within 120 days before SM. The primary outcome was cardiovascular hospitalizations (CVH) starting >30 days post‐SM. Results A total of 5324 patient (median age 62.0 [52.0–70.0], 53.2% female, 70% commercial insurance) underwent SM and 95.8% were followed >30 days post SM. During 2.7 (1.2–4.2) years median follow‐up, CVH occurred in 46.7% (80% of CVH within 16 months of SM). CVH for new atrial fibrillation/flutter was 25.4%, ventricular arrhythmias 9.7%, syncope 9.3%, myocardial infarction 5.2%, cardiac arrest 1.6%, ventricular septal defect 0.9%, and need for advanced heart failure therapy 0.6%. Repeat SM was required in 43 patients (0.8%). The strongest predictors of CVH post SM were presence of an implantable cardioverter‐defibrillator at baseline (adjusted odds ratio [aOR], 1.72 [95% CI, 1.50–1.97], P <0.001), chronic obstructive pulmonary disease (aOR, 1.65 [95% CI, 1.44–1.89], P <0.001), and chronic kidney disease (aOR, 1.45 [95% CI, 1.26–1.66], P <0.001). Conclusions Over a 3‐year period, SM for obstructive hypertrophic cardiomyopathy was associated with a high burden of CVH. Investigating the drivers of these events and strategies to mitigate the high incidence of intermediate and long‐term nonfatal complications post SM will help improve the care of patients with obstructive hypertrophic cardiomyopathy.