Impact of an exercise training program on cardiac neuronal function in heart failure patients on optimal medical therapy : A randomized Iodine-123 metaiodobenzylguanidine scintigraphy study

Impact of Long-Term Exercise-Based Cardiac Rehabilitation in Patients With Chronic Heart Failure - A Systematic Review and Meta-Analysis

BACKGROUND

This study aimed to clarify the effects of exercise-based cardiac rehabilitation (CR) on patients with heart failure.Methods and Results: Patients were divided into groups according to intervention duration (<6 and ≥6 months). We searched for studies published up to July 2023 in Embase, MEDLINE, PubMed, and the Cochrane Library, without limitations on data, language, or publication status. We included randomized controlled trials comparing the efficacy of CR and usual care on mortality, prehospitalization, peak oxygen uptake (V̇O2), and quality of life. Seventy-two studies involving 8,495 patients were included in this review. It was found that CR reduced the risk of rehospitalization for any cause (risk ratio [RR] 0.80; 95% confidence interval [CI] 0.70-0.92) and for heart failure (RR 0.88; 95% CI 0.78-1.00). Furthermore, CR was found to improve exercise tolerance (measured by peak V̇O2and the 6-min walk test) and quality of life. A subanalysis performed based on intervention duration (<6 and ≥6 months) revealed a similar trend.

CONCLUSIONS

Our meta-analysis showed that although CR does not reduce mortality, it is effective in reducing rehospitalization rates and improving exercise tolerance and quality of life, regardless of the intervention duration.

Complementary Role of Combined Indirect and Direct Cardiac Sympathetic (Hyper)Activity Assessment in Patients with Heart Failure by Spectral Analysis of Heart Rate Variability and Nuclear Imaging: Possible Application in the Evaluation of Exercise Training Effects

In chronic heart failure (CHF), abnormalities in cardiac autonomic control, characterized by sympathetic overactivity, contribute to the progression of the disease and are associated with an unfavorable prognosis. Assessing cardiac autonomic status is clinically important in the management of patients with CHF. To this aim, heart rate variability (HRV) analysis has been extensively used as a non-invasive tool for assessing cardiac autonomic regulation, and has been shown to predict the clinical outcome in patients with CHF. Adrenergic nerve activity has also been estimated using iodine-123 (I-123) metaiodobenzylguanidine (MIBG), a noradrenaline analogue. MIBG is an analogue of norepinephrine sharing the same cellular mechanism of uptake, storage, and release in presynaptic sympathetic neurons. As an innervation tracer, 123I-MIBG allows for the evaluation of cardiac sympathetic neuronal function. Cardiac MIBG imaging has also been reported to predict a poor clinical outcome in CHF. MIBG provides direct information on the function of the presynaptic sympathetic nerve endings, whereas HRV, which depends on postsynaptic signal transduction, reflects the end-organ response of the sinus node. The aim of this brief review is to provide the reader with some basic concepts regarding the spectral analysis of HRV and MIBG, highlighting what is known about their respective roles in detecting cardiac sympathetic hyperactivity in CHF and, in perspective, their possible combined use in assessing non-pharmacological treatments in patients with CHF and reduced ejection fraction, with a particular focus on the effects of exercise training.

Blood Lactate AUC Is a Sensitive Test for Evaluating the Effect of Exercise Training on Functional Work Capacity in Patients with Chronic Heart Failure

Purpose

Exercise training is an essential treatment option for patients with chronic heart failure (CHF). However, it remains controversial, which surrogate measures of functional work capacity are most reliable. The purpose of this paper was to compare functional capacity work measured as capillary lactate concentrations area under the curve (AUC) with standard cardiopulmonary exercise testing (CPET) with VO_2peak and the 6-minute walk test (6 MWT).

Methods

Twenty-three patients in New York Heart Association (NYHA) class II/III with left ventricular ejection fraction (LVEF) <35% were randomised to home-based recommendation of regular exercise (RRE) (controls), moderate continuous training (MCT) or aerobic interval training (AIT). The MCT and AIT groups underwent 12 weeks of supervised exercise training. Exercise testing was performed as standard CPET treadmill test with analysis of VO_2peak, the 6 MWT and a novel 30-minute submaximal treadmill test with capillary lactate AUC.

Results

All patients had statistically significant improvements in VO_2peak, 6 MWT and lactate AUC after 12 weeks of exercise training: 6 MWT (p =0.035), VO_2peak (p =0.049) and lactate AUC (p =0.002). Lactate AUC (p =0.046) and 6MWT (p =0.035), but not VO_2peak revealed difference between the exercise modalities regarding functional work capacity.

Conclusion

6-MWT and lactate AUC, but not VO_2peak, were able to reveal a statistically significant improvement in functional capacity between different exercise modalities.