Resting heart rate and heart rate reserve in advanced heart failure have distinct pathophysiologic correlates and prognostic impact: A prospective pilot study

Objectives: The purpose of this study was to compare the prognostic impact of clinical and biomarker correlates of resting heart rate (HR) and chronotropic incompetence in heart failure (HF) patients. Background: The mechanisms and underlying pathophysiological influences of HR abnormalities in HF are incompletely understood. Methods: In a prospective pilot study, 81 patients with advanced systolic HF (97% were receiving beta-blockers) and 25 age-, sex-, and body-size matched healthy controls underwent maximal cardiopulmonary exercise testing with sampling of neurohormones and biomarkers. Results: Two-thirds of HF patients met criteria for chronotropic incompetence. Resting HR and HR reserve (HRR, a measure of chronotropic response) were not correlated with each other and were associated with distinct biomarker profiles. Resting HR correlated with increased myocardial stress (B-type natriuretic peptide [BNP]: r = 0.26; pro-A-type natriuretic peptide: r = 0.24; N-terminal-proBNP: r = 0.32) and inflammation (leukocyte count: r = 0.28; high-sensitivity C-reactive protein assay: r = 0.25). In contrast, HRR correlated with the neurohumoral response to HF (copeptin: r = -0.33; norepinephrine: r = -0.29) but not with myocyte stress or injury reflected by natriuretic peptides or hs-troponin I. Patients in the lowest chronotropic incompetence quartile (HRR ≤0.38) displayed more advanced HF, reduced exercise capacity, ventilatory inefficiency, and poorer quality of life. Over a median follow-up of 17 months, the combined endpoint of death or urgent transplant/assist device implantation occurred more frequently in patients with higher resting HR (>67 beats/min) or lower HRR, with both markers providing additive prognostic information. Conclusions: Increased resting HR and chronotropic incompetence may reflect different pathophysiological processes, provide incremental prognostic information, and represent distinct therapeutic targets.