Abstract 16627: Predictors of Response to Exercise Training in Patients With Hypertrophic Cardiomyopathy

Abstract

Introduction: RESET-HCM was a randomized clinical trial of 16 weeks of moderate-intensity exercise training (ExT) in patients with hypertrophic cardiomyopathy (HCM). Compared with usual activity (UA), ExT resulted in a modest but significant 6% improvement in mean peak oxygen consumption (VO 2peak ), the best measure of cardiorespiratory fitness (CRF). Studies of heart failure populations have shown that ≥15% improvement in VO 2peak can be achieved with ExT. Hypothesis: We hypothesize that intervention-, disease-, and patient-specific factors differentially influence VO 2peak response to ExT. Methods: Data from 113 subjects were analyzed. Those who achieved ≥ 15% improvement in VO 2peak in response to ExT were categorized as high responders (HR), while low responders (LR) were those who did not. Baseline characteristics and activity log data were compared between HR and LR. Logistic regression investigated associations between VO 2peak response and these measures. Results: Twenty-two subjects were HR (16/57 [28.1%] in the ExT group vs. 6/56 [10.7%] in the UA group, p=0.02). HR had fewer comorbidities such as hypertension (9.1% vs 26.4%, p=0.03) and diabetes mellitus (0% vs 7.7%, p=0.01). Ejection fraction (EF) was lower among HR than LR (68.6% vs 71%, p=0.02), but other measures of cardiac remodeling, including hypertrophy and fibrosis burden, resting left ventricular outflow obstruction, and diastolic function did not differ. HR had lower baseline VO 2peak (18.4 vs 22.6 mL/kg/min, p=0.01). Although adherence to the frequency element of exercise prescriptions decreased over time in both groups, HR were 25% more adherent (p=0.02), exercising an average of 1 more day per week (3.8 vs 2.8, p=0.02). On multivariate analysis, baseline VO 2peak (OR: 0.79; 95% CI: 0.68-0.92) and EF (OR: 0.85; 95% CI: 0.74-0.98) were independent predictors of ≥15% improvement in VO 2peak after adjustment for age and sex. Higher exercise frequency (OR: 1.37; 95% CI: 0.97-1.95) was also an important factor. Conclusions: Higher exercise frequency, lower CRF at baseline, and lower EF predicted a greater magnitude of response to moderate intensity ExT in HCM patients. Future studies will be necessary to make the response to ExT more uniform across a heterogeneous group of HCM patients.