Mavacamten versus septal ablation: prognostic differences in 1-year cardiovascular events for HOCM with resting LVOTG ≥50 mmHg

Background Hypertrophic obstructive cardiomyopathy (HOCM) with significant left ventricular outflow tract obstruction (LVOTO) carries a high risk of heart failure and arrhythmias. While septal ablation and the targeted therapy mavacamten both effectively reduce left ventricular outflow tract gradients (LVOTG), their comparative impact on the clinical outcomes in real-world settings, particularly in Chinese cohorts, remains undefined. Purpose This study compares the 1-year cardiovascular outcomes between these two strategies. Methods A retrospective cohort study was conducted on consecutive HOCM patients admitted to the First Affiliated Hospital of Chongqing Medical University from January 2018 to December 2024, with the inclusion criterion of resting LVOTG ≥50 mmHg confirmed by echocardiography. Patients were stratified by initial treatment into a septal ablation group (n=49) and an oral mavacamten group (n=47). The primary endpoint was a 1-year composite of cardiovascular events: heart failure hospitalization, malignant ventricular arrhythmia, septal perforation, or cardiac arrest. Comprehensive baseline demographic, clinical, laboratory, and echocardiographic data were collected. Kaplan-Meier survival analysis and multivariable Cox regression were used to compare outcomes and identify independent predictors. Results At baseline, the ablation group was significantly younger (58.3±10.4 vs. 64.9±12.9 years, P=0.007) and had a higher proportion of males (46.9% vs. 25.5%, P=0.029) compared to the mavacamten group, though resting LVOTG were similar. Post-treatment, both interventions significantly reduced LVOTG (P<0.001 for both), with a more pronounced reduction observed in the ablation group (P<0.001). Despite this superior hemodynamic effect, the 1-year composite event rate was significantly higher in the ablation group (16.3% vs. 4.3%, P=0.016; unadjusted HR 5.27, 95%CI 1.15–24.06). After multivariable adjustment for age, sex, and other confounders, septal ablation remained an independent and potent risk factor for the primary endpoint (adjusted HR 11.24, 95%CI 1.55–83.33, P=0.017). No other baseline parameter showed independent predictive value. Conclusion In this real-world cohort of Chinese HOCM patients with severe LVOTO, mavacamten was associated with superior 1-year cardiovascular event-free survival compared to septal ablation. The finding that ablation was an independent predictor of adverse outcomes suggests that despite its hemodynamic efficacy, it may carry inherent procedural risks that influence the prognosis. These results underscore the need for individualized shared decision-making and larger prospective studies to guide treatment selection in this population.