Prognostic Value of the Hemodynamic Gain Index in Patients With Hypertrophic Cardiomyopathy

Hemodynamic gain index (HGI) is a novel, simple parameter calculated from resting and peak systolic blood pressure and heart rate (HR) during exercise, however, its prognostic value in patients with hypertrophic cardiomyopathy (HCM) is unknown. We investigate the prognostic value of alternative nonmetabolic exercise testing parameters in a contemporary HCM cohort. HGI was calculated from systolic blood pressure at rest and peak /HR data from consecutive HCM patients who underwent cardiopulmonary exercise testing for symptom evaluation. Multivariable Cox regression analysis was performed with the primary outcome of all-cause mortality and/or heart transplantation. Logistic regression models were used for HGI to predict the need for future myectomy or alcohol septal ablation. In our cohort of 905 patients with HCM, HGI correlated well with circulatory power (CP, r = 0.71, p <0.001) and peak VO₂ (r = 0.64, p <0.001). HGI (Area Under Curve (AUC) 0.87, 95% CI 0.81-0.92) demonstrated comparable accuracies to CP (AUC 0.88, 95% CI 0.83-0.92) and peak VO₂ (AUC 0.81, 95% CI 0.75-0.87) in predicting transplant-free survival. Higher HGI was independently associated with a lower risk of primary endpoint (adjusted HR 0.25, 95% CI 0.15-0.42, p <0.001), all-cause mortality (adjusted HR 0.31,95% CI 0.17-0.56, p <0.001), and was associated with lower risk for future myectomy or alcohol septal ablation (OR 0.78, 95% CI 0.67-0.91, p = 0.002). HGI may serve as an independent predictor for adverse outcomes in patients with HCM with comparable prognostic value to peak VO₂ and CP. In addition, HGI may identify those who would likely need myectomy or alcohol septal ablation, independent of pVO₂ evaluation.