Abstract 13106: Heart Rate Recovery and Chronotropic Response in Patients With Hypertrophic Cardiomyopathy
Background: Alterations in heart rate variability, abnormalities in catecholamine re-uptake by myocardial sympathetic nerve terminals and marked peripheral vasodilation during exercise have been reported in hypertrophic cardiomyopathy(HCM), suggesting impaired sympatho-vagal balance. This study was designed to evaluate the relationship between autonomic function, clinical, stress and imaging features in HCM patients.
Methods: 273 HCM patients and 94 age-matched healthy subjects were enrolled. HCM patients were classified into 4 groups based on heart rate recovery (HRR) 1st min and chronotropic response (CR). The clinical, stress characters, Echocardiographic and cardiac magnetic resonance (CMR) features were assessed.
Results: HCM patients had significantly lower HRR indices at 1~5min and higher prevalence of abnormal CR when compared to the control group (Table 1). Isolated impairment of HRR with normal CR (n=13) was seen in <5% of HCM patients - these patients had the highest LV mass and highest E/e’ ratio, indicating diastolic dysfunction. A combined impairment of CR and HRR (n=57) was seen in 20% of HCM patients - these patients were more symptomatic, had higher rest LVOT gradients and highest percentage of delayed enhancement (DE) on CMR, when compared to the rest of the HCM cohort. In contrast, HCM patients with both normal HRR and CR (n=118) were youngest, least symptomatic, had highest exercise capacity, lowest rest LVOT gradient, less diastolic dysfunction and less DE. Myectomy improved CR and reduced prevalence of abnormal BP response to exercise. Multivariate analysis showed that LA volume index had the strongest independent association with HRR. METs were associated with HRR and CR. E/e’ had the best linear correlation with HRR and CR.
Conclusions: HCM patients have a high prevalence of abnormal HRR and CR, suggesting autonomic imbalance. Myectomy improved CR and reduced abnormal BP response to exercise.
- © 2013 by American Heart Association, Inc.