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

Sigmoidal heart rate response pattern during exercise in patients with chronic heart failure

Detailed heart rate (HR) response patterns during exercise in patients with heart failure (HF) and sinus rhythm remain uncertain. We screened consecutive patients with HF who underwent cardiopulmonary exercise tests at a large academic center from November 2013 to July 2023. HR response during exercise was statistically classified using logistic differential equation models. A total of 99 patients were included. Of them, 75 patients were assigned to "sigmoidal pattern" and the other 24 to "exponential pattern." Patients with the sigmoidal pattern were older and exhibited higher plasma B-type natriuretic peptide levels. Increases in HR and oxygen consumption (V̇o2)/kg up to the anaerobic threshold level were not different between both patterns. However, beyond the threshold, the sigmoidal pattern group showed no further increase in HR and significantly lower V̇o2/kg than their counterparts (interactions for P < 0.001). HR response during exercise in patients with heart failure and sinus rhythm was categorized into two unique groups: sigmoidal and exponential patterns. More detailed clarification of the sigmoidal pattern, potentially indicating sinus node dysfunction, should offer new clinical insights for chronotropic incompetence.NEW & NOTEWORTHY Heart rate response patterns can be classified into two groups among patients with chronic heart failure reaching maximal exertion: sigmoidal and exponential.

Heart Rate Recovery: Up to Date in Heart Failure-A Literature Review

The rising prevalence of cardiovascular disease underscores the growing significance of heart failure (HF). Pathophysiological insights into HF highlight the dysregulation of the autonomic nervous system (ANS), characterized by sympathetic overactivity and diminished vagal tone, impacting cardiovascular function. Heart rate recovery (HRR), a metric measuring the heart's ability to return to its baseline rate post-exertion, plays a crucial role in assessing cardiovascular health. Widely applied across various cardiovascular conditions including HF, coronary artery disease (CAD), and arterial hypertension (HTN), HRR quantifies the difference between peak and recovery heart rates. Given its association with elevated sympathetic tone and exercise, HRR provides valuable insights into the perspective of HF, beyond effort tolerance, reaching toward prognostic and mortality indicators. Incorporating HRR into cardiovascular evaluations enhances our understanding of autonomic regulation in HF, offering potential implications for prognostication and patient management. This review addresses the significance of HRR in HF assessment, analyzing recently conducted studies, and providing a foundation for further research and clinical application.

Heart Rate Recovery Assessed by Cardiopulmonary Exercise Testing in Patients with Cardiovascular Disease: Relationship with Prognosis

BACKGROUND

The use of exercise testing has expanded in recent decades and there is a wealth of information examining the prognostic significance of exercise variables, such as peak oxygen consumption or ventilatory measures whilst exercising. However, a paucity of research has investigated the use of recovery-derived parameters after exercise cessation. Heart rate recovery (HRR) has been considered a measure of the function of the autonomic nervous system and its dysfunction is associated with cardiovascular risk.

OBJECTIVES

We aim to provide an overview of the literature surrounding HRR and its prognostic significance in patients with cardiovascular disease undertaking an exercise test.

DATA SOURCES

In December 2020, searches of PubMed, Scopus, and ScienceDirect were performed using key search terms and Boolean operators.

STUDY SELECTION

Articles were manually screened and selected as per the inclusion criteria.

RESULTS

Nineteen articles met inclusion criteria and were reviewed. Disagreement exists in methodologies used for measuring and assessing HRR. However, HRR provides prognostic mortality information for use in clinical practice.

CONCLUSIONS

HRR is a simple, non-invasive measure which independently predicts mortality in patients with heart failure and coronary artery disease; HRR should be routinely incorporated into clinical exercise testing.

Effects of chronotropic incompetence on exercise capacity in people with heart failure versus age-matched controls

Chronotropic incompetence (CI) is an inability to adequately raise heart rate during physiological stress. We established CI prevalence and exercise capacity in heart failure versus healthy age-matched controls. We conducted a systematic search (1966-July 1, 2020) and meta-analysis of studies reporting peak VO₂ in people with heart failure with reduced (HFrEF) and preserved (HFpEF) left ventricular ejection fraction and controls. Seventeen studies of 4410 participants were included, 4167 with heart failure and 243 age-matched controls. In both heart failure phenotypes, CI was more prevalent in HFrEF (51.7%) and HFpEF (55.8%) than in healthy controls (9%). Mortality was 24% higher in people with HFrEF and CI versus those with HFrEF and without CI; OR -1.24 (95% CI -2.20 to -0.28; p = 0.01). People with heart failure and CI had lower peak VO₂ than those without CI (MD) -3.30 ml kg^-1 min^-1 (95% CI -4.25 to -2.35, p < 0.01), and this was primarily driven by the HFrEF sub-population (MD) -3.86 ml kg^-1 min^-1 (95% CI -4.83 to -2.89, p < 0.01). Maximum heart rate MD -37.51 beats min^-1 (95% CI -41.99 to -33.03, p < 0.01) and maximum-resting heart rate were lower MD -29.44 beats min^-1 (95% CI -34.55 to -24.33, p < 0.01) in people with heart failure with CI vs without CI. People with heart failure and CI demonstrated similar respiratory exchange ratios (RER) to people with heart failure but without CI; (MD) -0.02 (95% CI -0.03 to -0.01), p < 0.01, suggesting that poor effort was unlikely to explain CI. CI is more prevalent in heart failure than in age-matched controls and although it is associated with lower peak VO₂ in HFrEF, it is unrelated to the lower peak VO₂ in HFpEF. RER values suggest poor effort is unlikely to explain these findings.

Prolonged heart rate recovery time after 6-minute walk test is an independent risk factor for cardiac events in heart failure: A prospective cohort study

OBJECTIVES

To determine whether the time for peak exercise heart rate to return to resting heart rate after the 6-minute walk test (6MWT) can predict cardiac events in patients with heart failure (HF) within 2 years.

DESIGN

Prospective cohort study.

SETTING

HF outpatient facility at a tertiary teaching hospital.

PARTICIPANTS

Seventy-six patients with HF, New York Heart Association functional classification II and III, and left ventricular ejection fraction <50%.

MAIN OUTCOME MEASURES

Patients used a heart rate monitor to measure the time for peak exercise heart rate to return to resting heart rate after the 6MWT. Data were analysed using Polar Pro-Trainer 5 software (Kempele, Finland). Patients were followed for >2 years for cardiac events (hospitalisations and death).

RESULTS

Thirty-four patients had cardiac events during the 2-year follow-up period. However, there was a significant difference in the time to return to resting heart rate between the groups with and without cardiac events {with 3.6 (SD 1.1) vs without 2.8 (SD 1.1) minutes; mean difference of 0.79 (95% confidence interval (CI) of the difference 0.28 to 1.28; P=0.003}. No significant differences between patients with and without cardiac events were found for mean walking distance, mean heart rate recovery at 1minute and mean heart rate recovery at 2minutes. The receiver operating curve discriminated between patients with and without cardiac events (área under the curve 0.71, 95% CI 0.61 to 0.81; P<0.001). Using logistic regression analysis, prolonged time to return to resting heart rate (≥3minutes) independently increased the risk for cardiac events 6.9-fold (95% CI 2.34 to 20.12; P<0.001). The Kaplan-Meier curve showed more cardiac events in patients with prolonged time to return to resting heart rate (P=0.028).

CONCLUSIONS

Prolonged time to return to resting heart rate (≥3minutes) after the 6MWT was an independent predictor of cardiac events in patients with HF.

Sacubitril/Valsartan Improves Autonomic Function and Cardiopulmonary Parameters in Patients with Heart Failure with Reduced Ejection Fraction

BACKGROUND

Heart rate recovery (HRR) is a marker of vagal tone, which is a powerful predictor of mortality in patients with cardiovascular disease. Sacubitril/valsartan (S/V) is a treatment for heart failure with reduced ejection fraction (HFrEF), which impressively impacts cardiovascular outcome. This study aims at evaluating the effects of S/V on HRR and its correlation with cardiopulmonary indexes in HFrEF patients.

METHODS

Patients with HFrEF admitted to outpatients' services were screened out for study inclusion. S/V was administered according to guidelines. Up-titration was performed every 4 weeks when tolerated. All patients underwent laboratory measurements, Doppler-echocardiography, and cardiopulmonary exercise stress testing (CPET) at baseline and at 12-month follow-up.

RESULTS

Study population consisted of 134 HFrEF patients (87% male, mean age 57.9 ± 9.6 years). At 12-month follow-up, significant improvement in left ventricular ejection fraction (from 28% ± 5.8% to 31.8% ± 7.3%, p < 0.0001), peak exercise oxygen consumption (VO2peak) (from 15.3 ± 3.7 to 17.8 ± 4.2 mL/kg/min, p < 0.0001), the slope of increase in ventilation over carbon dioxide output (VE/VCO2 slope )(from 33.4 ± 6.2 to 30.3 ± 6.5, p < 0.0001), and HRR (from 11.4 ± 9.5 to 17.4 ± 15.1 bpm, p = 0.004) was observed. Changes in HRR were significantly correlated to changes in VE/VCO2slope (r = -0.330; p = 0.003). After adjusting for potential confounding factors, multivariate analysis showed that changes in HRR were significantly associated to changes in VE/VCO2slope (Beta (B) = -0.975, standard error (SE) = 0.364, standardized Beta coefficient (Bstd) = -0.304, p = 0.009). S/V showed significant reduction in exercise oscillatory ventilation (EOV) detection at CPET (28 EOV detected at baseline CPET vs. 9 EOV detected at 12-month follow-up, p < 0.001). HRR at baseline CPET was a significant predictor of EOV at 12-month follow-up (B = -2.065, SE = 0.354, p < 0.001).

CONCLUSIONS

In HFrEF patients, S/V therapy improves autonomic function, functional capacity, and ventilation. Whether these findings might translate into beneficial effects on prognosis and outcome remains to be elucidated.

MicroRNAs Mediate Beneficial Effects of Exercise in Heart

MicroRNAs (miRNAs, miRs), a group of small non-coding RNAs, repress gene expressions at posttranscriptional level in most cases and are involved in cardiovascular physiology and disease pathogenesis. Increasing evidence has proved that miRNAs are potential regulators of exercise induced cardiac growth and mediate the benefits of exercise in a variety of cardiovascular diseases. In this chapter, we will review the regulatory effects of miRNAs in cardiac adaptations to exercise, and summarize their cardioprotective effects against myocardial infarction, ischemia/reperfusion injury, heart failure, diabetic cardiomyopathy, atherosclerosis, hypertension, and pulmonary hypertension. Also, we will introduce circulating miRNAs in response to acute and chronic exercise. Therefore, miRNAs may serve as novel therapeutic targets and potential biomarkers for cardiovascular diseases.