Abstract
Background: Sympathetic dysfunction can be evaluated by heart rate reserve (HRR) with exercise test. Objectives: To determine the value of HRR in predicting outcome of patients with hypertrophic cardiomyopathy (HCM). Methods: We enrolled 917 HCM patients (age = 49 ± 15 years, 516 men) assessed with exercise stress echocardiography (ESE) in 11 centres. ESE modality was semi-supine bicycle in 51 patients (6%), upright bicycle in 476 (52%), and treadmill in 390 (42%). During ESE, we assessed left ventricular outflow tract obstruction (LVOTO), stress-induced new regional wall motion abnormalities (RWMA), and HRR (peak/rest heart rate, HR). By selection, all patients completed the follow-up. Mortality was the predetermined outcome measure Results: During ESE, RWMA occurred in 22 patients (2.4%) and LVOTO (≥50 mmHg) in 281 (30.4%). HRR was 1.90 ± 0.40 (lowest quartile ≤ 1.61, highest quartile > 2.13). Higher resting heart rate (odds ratio 1.027, 95% CI: 1.018–1.036, p < 0.001), older age (odds ratio 1.021, 95% CI: 1.009–1.033, p < 0.001), lower exercise tolerance (mets, odds ratio 0.761, 95% CI: 0.708–0.817, p < 0.001) and resting LVOTO (odds ratio 1.504, 95% CI: 1.043–2.170, p = 0.029) predicted a reduced HRR. During a median follow-up of 89 months (interquartile range: 36–145 months), 90 all-cause deaths occurred. At multivariable analysis, lowest quartile HRR (Hazard ratio 2.354, 95% CI 1.116–4.968 p = 0.025) and RWMA (Hazard ratio 3.279, 95% CI 1.441–7.461 p = 0.004) independently predicted death, in addition to age (Hazard ratio 1.064, 95% CI 1.043–1.085 p < 0.001) and maximal wall thickness (Hazard ratio 1.081, 95% CI 1.037–1.128, p < 0.001). Conclusions: A blunted HRR during ESE predicts survival independently of RWMA in HCM patients.
Highlights
The assessment of mortality risk patients with hypertrophic cardiomyopathy (HCM)and little or no symptoms is a challenging task, and several approaches targeted on different physiologic variables have been proposed [1,2,3]
At univariate analysis the lowest quartile of heart rate reserve (HRR) predicted survival in the subset studied off (n = 524, Hazard ratio = 2.865—95% confidence interval (CI) 1.353–6.067, p = 0.006) or on (n = 383, Hazard ratio = 4.777—95% CI 1.078–21.777, p = 0.04) beta-blockers at the time of exercise stress echocardiography (ESE)
Our results suggest that this definable, accessible parameter is able to identify HCM patients at risk for future cardiac events
Summary
The assessment of mortality risk patients with hypertrophic cardiomyopathy (HCM)and little or no symptoms is a challenging task, and several approaches targeted on different physiologic variables have been proposed [1,2,3]. Since the three parameters focus on three different, important and largely unrelated pathophysiological targets, our study hypothesis is that left ventricular outflow tract obstruction (LVOTO), RWMA, and HRR during ESE may all independently contribute to improved risk stratification of HCM patients. To test this hypothesis, we evaluated LVOTG, RWMA, and HRR during ESE for predicting survival in HCM by interrogating the ESE multicentre data base built over the last 30 years with different generations of SE [7,8,9], and currently ongoing with SE 2020 [10].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
