Heart rate response to exercise in heart failure patients: The prognostic role of metabolic–chronotropic relation and heart rate recovery

Abstract

BackgroundThe dynamics of the sinus node response to exercise is linked to functional capacity and outcome in heart failure (HF). The goal of the work was to analyze determinants and impacts of cardio-acceleration, described by the concept of metabolic-chronotropic relation (MCR) and of cardio-deceleration, described by heart rate recovery (HRR). MethodsA cohort of 25 healthy controls and 78 patients with advanced systolic HF and optimized medical and/or device therapy (97% receiving beta-blockers, 54% ICD) underwent maximal cardiopulmonary exercise test and were prospectively followed. ResultsHF patients had impaired exercise performance compared with controls (pVO2 15±4 vs. 29±7ml.kg−1.min−1, p<0.0001) and lower both MCR slope (0.54±0.24 vs. 0.90±0.15, p<0.0001) and HRR (14.7±7.9 vs. 18.3±4.2min−1, p=0.03). In HF patients, MCR slope was inversely associated with beta-blocker dose (r=−0.24), NYHA class (r=−0.28) and HF duration (r=−0.25), whereas HRR with estimated glomerular filtration rate (eGFR, r=0.39), age (r=−0.28) and BMI (r=−0.31, all p<0.05). During a follow-up of 1269±933days, 64% patients experienced an adverse outcome (death, urgent transplantation, left ventricular assist device implantation). Those patients had higher NT-proBNP (p=0.02), worse left ventricular systolic function (LVEF, p=0.03) and lower MCR slope (p=0.02) but not HRR (p=0.19). MCR slope (but not HRR) was a significant outcome predictor (p=0.02 for Cox unadjusted model) even after adjustment for LVEF, serum natrium, systolic blood pressure, eGFR and NT-proBNP (p=0.04). ConclusionMCR slope is associated with different clinical variables than HRR. Compared to HRR, MCR slope provides significant prognostic information in HF patients.