Effect of exercise training on cardiovascular autonomic and muscular function in subclinical Chagas cardiomyopathy: a randomized controlled trial

Impact of cardiac structure and function on exercise intolerance in Chagas cardiomyopathy: Insights from CPET and echocardiography

INTRODUCTION

Chronic Chagas cardiomyopathy (CCC), the most severe clinical condition of Chagas disease, often leads to a reduction in functional capacity and the appearance of symptoms such as fatigue and dyspnea on exertion. However, its determinant factors remain unclear. We aimed to evaluate the peak oxygen consumption (VO2peak) in patients with CCC and identify its determining factors.

METHODS

An observational study with 97 CCC patients was conducted. Patients underwent clinical examination, cardiopulmonary exercise test (CPET), and echocardiography as part of the standard clinical evaluation. Multivariate linear regression was used to identify independent clinical and echocardiographic predictors of VO2peak and percentage of predicted VO2.

RESULTS

Mean age of study patients was 55.9 ± 13.4 years, median left ventricle ejection fraction (LVEF) was 40 (26-61.5) % and median VO2peak was 16.1 (12.1-20.8) ml/Kg/min. 36 patients presented preserved LVEF and 61 presented reduced LVEF. There were significant differences in almost all CPET variables (p < 0.05) between these two groups. VO2peak was associated with age, male sex, NYHA functional class, LVEF, left atrium diameter, LV diastolic diameter, E wave, LV mass index, and pulmonary artery systolic pressure (PASP). Age, male sex, LVEF, and E wave remained independently associated with VO2peak in the multivariate analysis (R2 = 0.69), furthermore, only LVEF and E wave were associated with the predicted VO2 percentage (R2 = 0.53).

CONCLUSION

In patients with CCC, disease severity, male sex, LV systolic and diastolic function influence the functional capacity.

Exercise Training Reduces Inflammation and Fibrosis and Preserves Myocardial Function and Perfusion in a Model of Chronic Chagas Cardiomyopathy

BACKGROUND

Chronic Chagas cardiomyopathy (CCC) is caused by an inflammatory process induced by Trypanosoma cruzi, which leads to myocarditis with reactive and reparative fibrosis. CCC progresses with myocardial perfusion abnormalities and histopathological events that affect cardiorespiratory fitness (CRF).

OBJECTIVES

We evaluated the effects of aerobic physical training (APT) on myocardial perfusion and on morphological and functional impairments related with inflammation and fibrosis in Syrian hamsters with CCC. As a secondary objective, we analyzed the cross-sectional areas of the skeletal muscle.

METHODS

Hamsters with CCC and their respective controls were divided into four groups: CCC sedentary, CCC-APT, sedentary control and APT control. Seven months after infection, the animals underwent echocardiography, myocardial perfusion scintigraphy and cardiopulmonary exercise testing. Moderate-intensity APT was performed for fifty minutes, five times a week, for eight weeks. Subsequently, the animals were reassessed. Histopathological analysis was conducted after the above-mentioned procedures. The level of significance was set at 5% in all analyses (p<0.05).

RESULTS

CCC sedentary animals presented worse myocardial perfusion defects (MPD) over time, reduced left ventricle ejection fraction (LVEF) and showed more inflammation and fibrosis when compared to other groups (mixed ANOVA analysis). Conversely, APT was able to mitigate the progression of MPD, ameliorate inflammation and fibrosis and improve CRF efficiency in CCC-APT animals.

CONCLUSIONS

Our study demonstrated that APT ameliorated cardiac dysfunction, MPD, and reduced inflammation and fibrosis in CCC hamster models. Additionally, CCC-SED animals presented skeletal muscle atrophy while CCC-APT animals showed preserved skeletal muscle CSA. Understanding APT's effects on CCC's pathophysiological dimensions is crucial for future research and therapeutic interventions.

The impact of exercise training on muscle sympathetic nerve activity: a systematic review and meta-analysis

The purpose of this systematic review and meta-analysis was to examine the effects of exercise training on muscle sympathetic nerve activity (MSNA) in humans. Studies included exercise interventions [randomized controlled trials (RCTs), nonrandomized controlled trials (non-RCTs), or pre-to-post intervention] that reported on adults (≥18 yr) where MSNA was directly assessed using microneurography, and relevant outcomes were assessed [MSNA (total activity, burst frequency, burst incidence, amplitude), heart rate, blood pressure (systolic blood pressure, diastolic blood pressure, or mean blood pressure), and aerobic capacity (maximal or peak oxygen consumption)]. Forty intervention studies (n = 1,253 individuals) were included. RCTs of exercise compared with no exercise illustrated that those randomized to the exercise intervention had a significant reduction in MSNA burst frequency and incidence compared with controls. This reduction in burst frequency was not different between individuals with cardiovascular disease compared with those without. However, the reduction in burst incidence was greater in those with cardiovascular disease [9 RCTs studies, n = 234, mean difference (MD) -21.08 bursts/100 hbs; 95% confidence interval (CI) -16.51, -25.66; I2 = 63%] compared with those without (6 RCTs, n = 192, MD -10.92 bursts/100 hbs; 95% CI -4.12, -17.73; I2 = 76%). Meta-regression analyses demonstrated a dose-response relationship where individuals with higher burst frequency and incidence preintervention had a greater reduction in values post-intervention. These findings suggest that exercise training reduces muscle sympathetic nerve activity, which may be valuable for improving cardiovascular health.NEW & NOTEWORTHY This systematic review and meta-analysis suggests exercise training reduces muscle sympathetic nerve activity (MSNA), which may be valuable for improving cardiovascular health. The reduction in burst incidence was greater among individuals with cardiovascular disease when compared with those without; exercise training may be particularly beneficial for individuals with cardiovascular disease. Meta-regression analyses demonstrated a dose-response relationship, where individuals with higher sympathetic activity preintervention had greater reductions in sympathetic activity post-intervention.

Clinical trials for Chagas disease: etiological and pathophysiological treatment

Chagas disease (CD) is caused by the flagellate protozoan Trypanosoma cruzi. It is endemic in Latin America. Nowadays around 6 million people are affected worldwide, and 75 million are still at risk. CD has two evolutive phases, acute and chronic. The acute phase is mostly asymptomatic, or presenting unspecific symptoms which makes it hard to diagnose. At the chronic phase, patients can stay in the indeterminate form or develop cardiac and/or digestive manifestations. The two trypanocide drugs available for the treatment of CD are benznidazole (BZ) and nifurtimox (NFX), introduced in the clinic more than five decades ago. WHO recommends treatment for patients at the acute phase, at risk of congenital infection, for immunosuppressed patients and children with chronic infection. A high cure rate is seen at the CD acute phase but better treatment schemes still need to be investigated for the chronic phase. There are some limitations within the use of the trypanocide drugs, with side effects occurring in about 40% of the patients, that can lead patients to interrupt treatment. In addition, patients with advanced heart problems should not be treated with BZ. This is a neglected disease, discovered 114 years ago that still has no drug effective for their chronic phase. Multiple social economic and cultural barriers influence CD research. The high cost of the development of new drugs, in addition to the low economical return, results in the lack of investment. More economic support is required from governments and pharmaceutical companies on the development of more research for CD treatment. Two approaches stand out: repositioning and combination of drugs, witch drastically decrease the cost of this process, when compared to the development of a new drug. Here we discuss the progress of the clinical trials for the etiological and pathophysiological treatment for CD. In summary, more studies are needed to propose a new drug for CD. Therefore, BZ is still the best option for CD. The trials in course should clarify more about new treatment regimens, but it is already possible to indicate that dosage and time of treatment need to be adjusted.

Exercise-based training programs for patients with chronic Chagas cardiomyopathy: A systematic review and meta-analysis

Background

We assessed the effects of exercise-based training programs (EBTP) in patients with chronic Chagas cardiomyopathy (CCC) through a systematic review and meta-analysis.

Methods

We conducted a search in Pubmed/Medline, Embase, Scopus, Web of Science, Cochrane Library, Virtual Health Library, and SciELO until January 2023. Randomized controlled trials (RCTs) and non-randomized intervention studies (NRIS) investigating the effects of EBTP in CCC patients were included. The primary outcomes were all-cause mortality, cardiovascular mortality, and health-related quality of life (HRQoL), and the secondary outcomes were exercise capacity by peak VO2, heart failure-related hospital admissions (HFRHA), and left ventricular ejection fraction (LVEF).

Results

The search strategy yielded 3617 studies. After removing duplicates and screening, eight studies (3 RCTs and 5 NRIS) involving 222 patients were included. Seven studies were conducted in Brazil. The age range was from 30 to 71 years, and 47.1% were male. Data on mortality, HRQoL, LVEF, and HFRHA were scarcely reported. The meta-analysis pooling four studies showed that the peak VO2 was significantly higher (mean difference 4.45, 95% confidence interval 3.50 to 5.39 mL/kg/min, I2 = 0%) in the EBTP group compared to the control group.

Conclusion

The evidence available was limited and heterogeneous. While EBTP has shown to improve HRQoL and exercise capacity, there is no conclusive information about the other proposed outcomes. These positive effects present an opportunity to provide treatment to CCC patients in low- and middle-income countries. Further studies are needed to ascertain the effects of EBTP on hard outcomes in this population.Registration number: CRD42022334060.

The Effects Of Exercise Training On Physical, Physiological And Psychological Risk Factors Of Patients With Cardiovascular Disease

Background — Exercise training is an important component of wellness for individuals diagnosed with cardiovascular disease (CVD). Exercise may have an effect on cardiovascular risk factors such as hypertension, lipid levels, and other associated physical, psychological, and physiological risk factors. Exercise intensity may further impact those risk factors. Aim — This narrative review of the literature aims to identify the effect of regular physical exercise on modifying risk factors for CVD and increased morbidity and mortality related to CVD. Methods — Published English-language papers from 2011 to 2020, available in Scopus, PubMed, Cochrane, Google Scholar, and Thompson were included in this review. Keywords for this search were exercise training, cardiovascular disease, hypertension, physical function, physiological, and psychological risk factors. Conclusions — Exercise training may be a cost-effective intervention that improves the physical, physiological, and psychological risk factors and the motor function of patients with cardiovascular disease.