Distinct Subgroups and Outcomes in Patients With Hypertrophic Obstructive Cardiomyopathy After Septal Myectomy.

Abstract

Hypertrophic obstructive cardiomyopathy (HOCM) is a structurally heterogeneous disease with variable clinical outcomes. Although septal myectomy provides symptomatic benefits, interindividual differences in postoperative risk and long-term prognosis remain unknown. A retrospective cohort of 699 patients with HOCM was analyzed. A latent class analysis model was derived to identify distinct subgroups. Group-specific postoperative and long-term outcomes were compared. A decision tree model was developed to simplify clinical classification. Three subgroups were identified: group 1 (younger patients), group 2 (older patients with a smaller left atrial diameter [LAD]), and group 3 (older patients with an enlarged LAD). Compared with group 1, group 3 had a significantly higher risk of postoperative new-onset atrial fibrillation, prolonged ventilation, renal failure, and composite complications. During a median follow-up of 7.7 years, group 3 showed an increased risk of composite outcome of all-cause mortality and cardiac readmission (adjusted hazard ratio, 1.67; 95% CI, 1.13-2.45; P = .009) and major adverse cardiac and cerebrovascular events (adjusted hazard ratio, 2.18; 95% CI, 1.17-4.05; P = .014). Group 1 had the highest risk of ventricular arrhythmias compared with group 2 (adjusted hazard ratio, 2.58; 95% CI, 1.20-5.57; P = .016). A simplified decision tree using age ≥50 years and LAD ≥42 mm achieved a classification accuracy of 95.7%. Latent class analysis revealed distinct subgroups of HOCM. Older patients with an enlarged LAD had the highest cardiovascular risk, whereas younger patients had an elevated arrhythmia risk. Subgroup-based stratification may inform personalized perioperative and long-term surveillance strategies in patients with HOCM.