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Published on: February 13, 2021
Resting Heart Rate and Chronotropic Response to Exercise: Prognostic Implications in Heart Failure Across the Left
Mário Santos1, Erin West2, Hicham Skali2
1Department of Physiology and Cardiothoracic Surgery, Cardiovascular R&D Unit, Faculty of Medicine, University of Porto, Portugal; Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
Insights
Higher resting heart rate (HR) and impaired chronotropic response to exercise (CIx) are independent predictors of worse outcomes in heart failure (HF) patients. These markers offer additive prognostic value across the full spectrum of left ventricle ejection fraction (LVEF).
Area of Science:
- Cardiology
- Clinical Medicine
- Exercise Physiology
Background:
- Heart failure (HF) management requires accurate prognostic markers.
- Resting heart rate (HR) and exercise-induced chronotropic response are potential indicators of HF severity.
- Understanding their relationship with clinical outcomes across different left ventricle ejection fraction (LVEF) categories is crucial.
Purpose of the Study:
- To investigate the association between resting HR, chronotropic index (CIx), and clinical outcomes in a broad HF population.
- To determine if resting HR and CIx provide independent or additive prognostic information.
- To assess if these relationships vary based on LVEF.
Main Methods:
- A cohort of 718 patients with HF underwent exercise testing to assess resting HR and CIx.
- Clinical outcomes, including device implantation, transplantation, or death, were tracked over a median of 4.4 years.
- Cox regression models, adjusted for multiple clinical factors, were used to evaluate prognostic associations.
Main Results:
- Resting HR and CIx were poorly correlated and did not predict each other.
- Higher resting HR (per 5 bpm increase) and lower CIx (per SD change) were independently associated with adverse clinical outcomes.
- These prognostic associations were consistent across the spectrum of LVEF, with no significant heterogeneity.
Conclusions:
- Resting HR and CIx are independent prognostic markers in HF patients.
- Both parameters offer additive value for predicting clinical outcomes, regardless of LVEF.
- These findings highlight the importance of assessing both resting HR and chronotropic response in HF risk stratification.
Background:
We studied the relationship between resting heart rate (HR), chronotropic response to exercise, and clinical outcomes in patients with heart failure (HF) across the spectrum of left ventricle ejection fraction (LVEF).
Methods And Results:
Resting HR and chronotropic index (CIx) were assessed in 718 patients with HF (53 ± 14 years of age, 66% male) referred for exercise testing. Associations with the composite outcome of left ventricular assist device implantation, transplantation, or death (151 events, 4.4 [range 3.0-5.8] years of follow-up) were assessed with the use of Cox models adjusted for age, sex, HF etiology, diabetes, LVEF, beta-blocker use, device therapy, estimated glomerular filtration rate, and peak oxygen uptake. Resting HR was 73 ± 15 beats/min, CIx was 0.60 ± 0.26, LVEF was 34% ± 15%, and 39% had an LVEF ≥40%. Resting HR correlated poorly with CIx (r = 0.08; P = .04) and did not predict (P = .84) chronotropic incompetence (CIx <0.60). Both higher resting HR (per 5 beats/min increase: adjusted hazard ratio [HR] -1.05, 95% confidence interval [CI] 1.00-1.11) and CIx (per SD change: adjusted HR -0.77, 95% CI 0.62-0.94) were independent prognostic markers. No heterogeneity of effect was noted based on LVEF (P >.05).
Conclusion:
Higher resting HR and lower CIx are both associated with more severe HF, but correlated poorly with each other. They provide independent and additive prognostic information in HF across the LVEF spectrum.
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