Cardiovascular Hospitalizations Burden Following Septal Myectomy for Obstructive Hypertrophic Cardiomyopathy

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. 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. 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). 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.