Exercise training without ventricular remodeling in patients with moderate to severe left ventricular dysfunction early after acute myocardial infarction

Influence of Physical Training after a Myocardial Infarction on Left Ventricular Contraction Mechanics

BACKGROUND

Exercise plays a positive role in the course of the ischemic heart disease, enhancing functional capacity and preventing ventricular remodeling.

OBJECTIVE

To investigate the impact of exercise on left ventricular (LV) contraction mechanics after an uncomplicated acute myocardial infarction (AMI).

METHODS

A total of 53 patients was included, 27 of whom were randomized to a supervised training program (TRAINING group), and 26 to a CONTROL group, who received usual recommendations on physical exercise after AMI. All patients underwent cardiopulmonary stress testing and a speckle tracking echocardiography to measure several parameters of LV contraction mechanics at one month and five months after AMI. A p value < 0.05 was considered statistically significant for the comparisons of the variables.

RESULTS

No significant difference were found in the analysis of LV longitudinal, radial and circumferential strain parameters between groups after the training period. After the training program, analysis of torsional mechanics demonstrated a reduction in the LV basal rotation in the TRAINING group in comparison to the CONTROL group (5.9±2.3 vs. 7.5±2.9o; p=0.03), and in the basal rotational velocity (53.6±18.4 vs.68.8±22.1 º/s; p=0.01), twist velocity (127.4±32.2 vs. 149.9±35.9 º/s; p=0.02) and torsion (2.4±0.4 vs. 2.8±0.8 º/cm; p=0.02).

CONCLUSIONS

Physical activity did not cause a significant improvement in LV longitudinal, radial and circumferential deformation parameters. However, the exercise had a significant impact on the LV torsional mechanics, consisting of a reduction in basal rotation, twist velocity, torsion and torsional velocity which can be interpreted as a ventricular "torsion reserve" in this population.

Short- and Long-Term Effects of High-Intensity Interval Training vs. Moderate-Intensity Continuous Training on Left Ventricular Remodeling in Patients Early After ST-Segment Elevation Myocardial Infarction-The HIIT-EARLY Randomized Controlled Trial

Aim

Due to insufficient evidence on the safety and effectiveness of high-intensity interval training (HIIT) in patients early after ST-segment elevation myocardial infarction (STEMI), we aimed to compare short- and long-term effects of randomized HIIT or moderate-intensity continuous training (MICT) on markers of left ventricular (LV) remodeling in STEMI patients receiving optimal guideline-directed medical therapy (GDMT).

Materials and Methods

Patients after STEMI (<4 weeks) enrolled in a 12-week cardiac rehabilitation (CR) program were recruited for this randomized controlled trial (NCT02627586). During a 3-week run-in period with three weekly MICT sessions, GDMT was up-titrated. Then, the patients were randomized to HIIT or isocaloric MICT for 9 weeks. Echocardiography and cardiopulmonary exercise tests were performed after run-in (3 weeks), end of CR (12 weeks), and at 1-year follow-up. The primary outcome was LV end-diastolic volume index (LVEDVi) at the end of CR. Secondary outcomes were LV global longitudinal strain (GLS) and cardiopulmonary fitness.

Results

Seventy-three male patients were included, with the time between STEMI and start of CR and randomization being 12.5 ± 6.3 and 45.8 ± 10.8 days, respectively. Mixed models revealed no significant group × time interaction for LVEDVi at the end of CR (p = 0.557). However, there was a significantly smaller improvement in GLS at 1-year follow-up in the HIIT compared to the MICT group (p = 0.031 for group × time interaction). Cardiorespiratory fitness improved significantly from a median value of 26.5 (1st quartile 24.4; 3rd quartile 1.1) ml/kg/min at randomization in the HIIT and 27.7 (23.9; 31.6) ml/kg/min in the MICT group to 29.6 (25.3; 32.2) and 29.9 (26.1; 34.9) ml/kg/min at the end of CR and to 29.0 (26.6; 33.3) and 30.6 (26.0; 33.8) ml/kg/min at 1 year follow-up in HIIT and MICT patients, respectively, with no significant group × time interactions (p = 0.138 and 0.317).

Conclusion

In optimally treated patients early after STEMI, HIIT was not different from isocaloric MICT with regard to short-term effects on LVEDVi and cardiorespiratory fitness. The worsening in GLS at 1 year in the HIIT group deserves further investigation, as early HIIT may offset the beneficial effects of GDMT on LV remodeling in the long term.

Effect of home-based high-intensity interval training versus moderate-intensity continuous training in patients with myocardial infarction: a randomized controlled trial

Background

Supervised high-intensity interval training (HIIT) has been proposed to be more effective than moderate-intensity continuous training (MICT) for improving exercise capacity, but there are not sufficient information effects of home-based HIIT and MICT in patients with myocardial infarction (MI).

Aims

To compare the effects of home-based HIIT and MICT in patients with MI.

Methods

Twenty-one patients with MI were randomly assigned to one of two home-based exercise modes: HIIT group and MICT group. Home-based HIIT and MICT were performed twice a week for 12 weeks with an exercise intensity of 85–95% of heart rate (HR) reserve and 70–75% HR reserve, respectively. The primary outcome measure was functional capacity. Secondary outcomes included resting blood pressure and HR, peripheral oxygen saturation, pulmonary function and respiratory muscle strength, dyspnea severity, body composition (body fat%, body mass ındex (BMI), fat free muscle), peripheral muscle strength, and health-related quality of life (HRQoL).

Results

Functional capacity, measured by 6-minute walk test, increased in HIIT and MICT group (p < 0.05). Resting BP and HR, body fat%, and BMI were significantly decreased, and pulmonary functions, respiratory-peripheral muscle strength, and HRQoL were significantly increased in the both groups (p < 0.05). Home-based HIIT was more effective than MICT in improving pulmonary functions and lower extremity muscle strength (p < 0.05).

Conclusions

This study suggests that HIIT and MICT can be applied at home-based in patients with MI and play an important role in improving functional capacity, health outcomes, and HRQoL.

Trial registration

Clinical Trials Number: NCT04407624.

Role of Left Ventricle Function in Cardiac Rehabilitation Outcomes in Stage B Heart Failure Patients

PURPOSE

To study the role of left ventricle systolic function in cardiac rehabilitation program (CRP) response in stage B heart failure patients.

METHODS

A retrospective analysis was completed of 691 patients with previous myocardial infarction that underwent a CRP, classified in 3 groups: preserved ejection fraction (pEF), mid-range ejection fraction (mrEF), and reduced ejection fraction (rEF). We compared the response to CRP analyzing the relative changes of estimated cardiorespiratory fitness (CRFe), resting heart rate (HR), and chronotropic index (CI).

RESULTS

After exercise training (median [interquartile range]) mrEF (23.9% [9.7, 40.8]) and rEF (23.9% [9.7, 41.2]) groups had a better CRFe response to CRP than pEF groups (17.6% [0.0, 35.9]), P = .009. CI increased similarly in all groups. We found a small effect of CRP on resting HR.

CONCLUSION

Exercise-based CRP yields notable benefits to mrEF and rEF groups and the magnitude of its benefits is, at least, similar to that found in pEF patients.

Home-based exercise is associated with improved cardiac functional performance in patients after acute myocardial infarction

OBJECTIVE

To evaluate the effects of home-based exercise and physical activity on cardiac functional performance in patients after acute myocardial infarction (MI) during the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

This retrospective study enrolled patients that received treatment of acute ST-segment elevation MI between and were followed-up 6 months later. The patients were divided into physically active and inactive groups based on their levels of home exercise after hospital discharge.

RESULTS

A total of 78 patients were enrolled in the study: 32 were physically active and 46 were physically inactive. The baseline characteristics were comparable between the two groups. At the 6-month visit, left ventricular ejection fraction and six-minute walking test (6MWT) were significantly improved while the proportion of patients with a New York Heart Association (NYHA) functional III classification was decreased in the active patients, whereas these parameters were not significantly changed in the inactive patients. In addition, the 6MWT was greater while the proportion of patients with an NYHA III classification was lower in the active group than the inactive group at the 6-month visit.

CONCLUSION

Maintaining physical activity at home was associated with improved cardiac functional performance in patients after acute MI during the COVID-19 pandemic.

Early moderate exercise benefits myocardial infarction healing via improvement of inflammation and ventricular remodelling in rats

Thus far, the cellular and molecular mechanisms related to early (especially within 24 hours after acute myocardial infarct (MI)) exercise‐mediated beneficial effects on MI have not yet been thoroughly established. In the present study, we demonstrated that acute MI rats that underwent early moderate exercise training beginning one day after MI showed no increase in mortality and displayed significant improvements in MI healing and ventricular remodelling, including an improvement in cardiac function, a decrease in infarct size, cardiomyocyte apoptosis, cardiac fibrosis and cardiomyocyte hypertrophy, and an increase in myocardial angiogenesis, left ventricular wall thickness and the number of cardiac telocytes in the border zone. Integrated miRNA‐mRNA profiling analysis performed by the ingenuity pathway analysis system revealed that the inhibition of the TGFB1 regulatory network, activation of leucocytes and migration of leucocytes into the infarct zone comprise the molecular mechanism underlying early moderate exercise‐mediated improvements in cardiac fibrosis and the pathological inflammatory response. The findings of the present study demonstrate that early moderate exercise training beginning one day after MI is safe and leads to significantly enhanced MI healing and ventricular remodelling. Understanding the mechanism behind the positive effects of this early training protocol will help us to further tailor suitable cardiac rehabilitation programmes for humans.

The impact of high-intensity interval training on ventricular remodeling in patients with a recent acute myocardial infarction-A randomized training intervention pilot study

Background

Aerobic exercise training is associated with beneficial ventricular remodeling and an improvement in cardiac biomarkers in chronic stable heart failure. High‐intensity interval training (HIIT) is a time‐efficient method to improve V˙O2peak in stable coronary heart disease patients. This pilot study aimed to compare the effect of HIIT on ventricular remodeling in patients with a recent acute myocardial infarction (AMI).

Methods

Nineteen post‐AMI patients were randomized to either HIIT (n = 9) or usual care (n = 10). A cardiopulmonary exercise test (CPET), transthoracic echocardiography, and cardiac biomarker assessment (ie, N‐terminal pro B‐type natriuretic peptide levels and G protein‐coupled receptor kinase 2 expression) were performed before and after a 12‐week training intervention. CPET parameters including oxygen uptake efficiency slope (OUES) and V˙O2 at the first ventilatory threshold (V˙O2 VT1) were calculated. left ventricular (LV) structural and functional echocardiographic parameters including myocardial strain imaging were assessed.

Results

V˙O2peak and OUES improved solely in the HIIT group (P < .05 for group/time, respectively). There was a significant training effect for the improvement of peak work load in both groups (P < .05). O₂ pulse and V˙O2 at VT1 both improved only in the HIIT group (P < .05 for time, no interaction). HIIT improved radial strain and pulsed‐wave tissue Doppler imaging derived e′ (P < .05 for time, no interaction). Cardiac biomarkers did not change in either group.

Conclusions

In post‐AMI patients, HIIT lead to significant improvements in prognostic CPET parameters compared to usual care. HIIT was associated with favorable ventricular remodeling regarding certain echocardiographic parameters of LV function.

Aerobic Training after Myocardial Infarction: Remodeling Evaluated by Cardiac Magnetic Resonance

Background

Numerous studies show the benefits of exercise training after myocardial infarction (MI). Nevertheless, the effects on function and remodeling are still controversial.

Objectives

To evaluate, in patients after (MI), the effects of aerobic exercise of moderate intensity on ventricular remodeling by cardiac magnetic resonance imaging (CMR).

Methods

26 male patients, 52.9 ± 7.9 years, after a first MI, were assigned to groups: trained group (TG), 18; and control group (CG), 8. The TG performed supervised aerobic exercise on treadmill twice a week, and unsupervised sessions on 2 additional days per week, for at least 3 months. Laboratory tests, anthropometric measurements, resting heart rate (HR), exercise test, and CMR were conducted at baseline and follow-up.

Results

The TG showed a 10.8% reduction in fasting blood glucose (p = 0.01), and a 7.3-bpm reduction in resting HR in both sitting and supine positions (p < 0.0001). There was an increase in oxygen uptake only in the TG (35.4 ± 8.1 to 49.1 ± 9.6 mL/kg/min, p < 0.0001). There was a statistically significant decrease in the TG left ventricular mass (LVmass) (128.7 ± 38.9 to 117.2 ± 27.2 g, p = 0.0032). There were no statistically significant changes in the values of left ventricular end-diastolic volume (LVEDV) and ejection fraction in the groups. The LVmass/EDV ratio demonstrated a statistically significant positive remodeling in the TG (p = 0.015).

Conclusions

Aerobic exercise of moderate intensity improved physical capacity and other cardiovascular variables. A positive remodeling was identified in the TG, where a left ventricular diastolic dimension increase was associated with LVmass reduction.

Exercise attenuates inflammation and limits scar thinning after myocardial infarction in mice

Although exercise mediates beneficial effects in patients after myocardial infarction (MI), the underlying mechanisms as well as the question of whether an early start of exercise after MI is safe or even beneficial are incompletely resolved. The present study analyzed the effects of exercise before and reinitiated early after MI on cardiac remodeling and function. Male C57BL/6N mice were housed sedentary or with the opportunity to voluntarily exercise for 6 wk before MI induction (ligation of the left anterior descending coronary artery) or sham operation. After a 5-day exercise-free phase after MI, mice were allowed to reexercise for another 4 wk. Exercise before MI induced adaptive hypertrophy with moderate increases in heart weight, cardiomyocyte diameter, and left ventricular (LV) end-diastolic volume, but without fibrosis. In sedentary mice, MI induced eccentric LV hypertrophy with massive fibrosis but maintained systolic LV function. While in exercised mice gross LV end-diastolic volumes and systolic function did not differ from sedentary mice after MI, LV collagen content and thinning of the infarcted area were reduced. This was associated with ameliorated activation of inflammation, mediated by TNF-α, IL-1β, and IL-6, as well as reduced activation of matrix metalloproteinase 9. In contrast, no differences in the activation patterns of various MAPKs or adenosine receptor expressions were observed 5 wk after MI in sedentary or exercised mice. In conclusion, continuous exercise training before and with an early reonset after MI ameliorates adverse LV remodeling by attenuating inflammation, fibrosis, and scar thinning. Therefore, an early reonset of exercise after MI can be encouraged.

Cardiac remodeling and physical training post myocardial infarction

After myocardial infarction (MI), the heart undergoes extensive myocardial remodeling through the accumulation of fibrous tissue in both the infarcted and noninfarcted myocardium, which distorts tissue structure, increases tissue stiffness, and accounts for ventricular dysfunction. There is growing clinical consensus that exercise training may beneficially alter the course of post-MI myocardial remodeling and improve cardiac function. This review summarizes the present state of knowledge regarding the effect of post-MI exercise training on infarcted hearts. Due to the degree of difficulty to study a viable human heart at both protein and molecular levels, most of the detailed studies have been performed by using animal models. Although there are some negative reports indicating that post-MI exercise may further cause deterioration of the wounded hearts, a growing body of research from both human and animal experiments demonstrates that post-MI exercise may beneficially alter the course of wound healing and improve cardiac function. Furthermore, the improved function is likely due to exercise training-induced mitigation of renin-angiotensin-aldosterone system, improved balance between matrix metalloproteinase-1 and tissue inhibitor of matrix metalloproteinase-1, favorable myosin heavy chain isoform switch, diminished oxidative stress, enhanced antioxidant capacity, improved mitochondrial calcium handling, and boosted myocardial angiogenesis. Additionally, meta-analyses revealed that exercise-based cardiac rehabilitation has proven to be effective, and remains one of the least expensive therapies for both the prevention and treatment of cardiovascular disease, and prevents re-infarction.

[Effects of long-term exercise training on left ventricular function and remodeling in patients with anterior wall myocardial infarction]

OBJECTIVE

To assess the effects of long-term exercise training on the function and remodeling of the left ventricle after myocardial infarction.

METHODS

We studied 90 patients with a first acute anterior-wall myocardial infarction, all received conventional medical treatment. Symptom-limited maximal exercise stress tests, echocardiograms and effort-rest isotopic ventriculographies at 2, 6 and 12 months after myocardial infarction were performed; the follow-up time averaged 36.3±17 months. All patients joined a cardiac rehabilitation program with moderate or intense exercise training lasting at least a year. Of all patients, 41.1% suffered severe left ventricle dysfunction.

RESULTS

Ergometric parameters that expressed functional capacity increased significantly (P<.0005) at the sixth month evaluation and remained unchanged after a year. There was significant decrease (P<.01) of exercise myocardial ischemia at 6 months. The variables that measured size and function of left ventricle did not change during evolution. Morbidity amounted to 16.7% and total mortality of the series was 13.3%, with 8.9% of cardiovascular cause.

CONCLUSIONS

Long-term exercise training showed no deleterious effects on left ventricle function or remodeling and beneficial functional and clinical effects were obtained in these rehabilitated postinfarction patients.

The CopenHeartSF trial--comprehensive sexual rehabilitation programme for male patients with implantable cardioverter defibrillator or ischaemic heart disease and impaired sexual function: protocol of a randomised clinical trial

INTRODUCTION

Sexuality is an important part of people's physical and mental health. Patients with heart disease often suffer from sexual dysfunction. Sexual dysfunction has a negative impact on quality of life and well-being in persons with heart disease, and sexual dysfunction is associated with anxiety and depression. Treatment and care possibilities seem to be lacking. Studies indicate that non-pharmacological interventions such as exercise training and psychoeducation possess the potential of reducing sexual dysfunction in patients with heart disease. The CopenHeartSF trial will investigate the effect of a comprehensive sexual rehabilitation programme versus usual care.

METHODS AND ANALYSIS

CopenHeartSF is an investigator-initiated randomised clinical superiority trial with blinded outcome assessment, with 1:1 central randomisation to sexual rehabilitation plus usual care versus usual care alone. Based on sample size calculations, 154 male patients with impaired sexual function due to implantable cardioverter defibrillator or ischaemic heart disease will be included from two university hospitals in Denmark. All patients receive usual care and patients allocated to the experimental intervention group follow a 12-week sexual rehabilitation programme consisting of an individualised exercise programme and psychoeducative consultation with a specially trained nurse. The primary outcome is sexual function measured by the International Index of Erectile Function. The secondary outcome measure is psychosocial adjustment to illness by the Psychosocial Adjustment to Illness Scale, sexual domain. A number of explorative analyses will also be conducted.

ETHICS AND DISSEMINATION

CopenHeartSF is approved by the regional ethics committee (no H-4-2012-168) and the Danish Data Protection Agency (no 2007-58-0015) and is performed in accordance with good clinical practice and the Declaration of Helsinki in its latest form.

REGISTRATION

Clinicaltrials.gov identifier: NCT01796353.

Effects of Short-term Exercise Training on Cardiorespiratory Fitness of Male Adults with Myocardial Infarction

[Purpose] The purpose of this study was to determine the effects of short-term exercise training on the cardiorespiratory fitness (CRF) of individuals suffering from myocardial infarction. [Subjects] A total of 60 participants were divided into experimental (EXP; n=30, mean age 56.7 ± 2.8 years, body mass 80.7 ± 10.7 kg, body height 171.9 ± 7.2 cm) and control (CON; n=30, mean age 56.5 ± 3.1 years, body mass 84.4 ± 12.4 kg, body height 171.5 ± 12.4 cm) groups. [Methods] The members of the EXP group took part in an organized daily physical exercise program (Monday through Sunday), for a period of 3 weeks. The exercise program consisted of 60 min daily specialized fitness exercises with an intensity ranging from 55-70% of the maximum heart rate, which was determined by test on a bicycle ergometer. The effects of the exercise were monitored by means of the following parameters: maximum oxygen uptake (VO2peak), resting heart rate, systolic blood pressure and diastolic blood pressure. [Results] The results indicate statistically significant post-exercise improvements in heart rate, relative oxygen uptake and systolic blood pressure, among the members of the EXP group. The results indicate that at the initial measurement of cardiorespiratory fitness no statistically significant differences were found between the groups at the multivariate level (Wilk's λ=0.83), while statistically significant differences in the cardiorespiratory fitness were found at the final measurement (Wil's λ=0.430). [Conclusion] The obtained results indicate that the exercise program, which lasted for a period of 21 days, though shorter in duration than other programs still led to statistically significant changes in the CRF of individuals suffering from MI.

The effect of high-intensity aerobic interval training on postinfarction left ventricular remodelling

This is the third in a series of case studies on an individual with normal coronaries who sustained an idiopathic acute myocardial infarction . Bilateral pulmonary emboli almost 2 years post-myocardial infarction (MI) revealed coagulopathy as the cause. The original MI resulted in 16% myocardial scar tissue. An increasing number of patients are surviving MI, hence the burden for healthcare often shifts to heart failure. Accumulating evidence suggests high-intensity aerobic interval exercise (AHIT) is efficacious in improving cardiac function in health and disease. However, its impact on MI scar has never been assessed. Accordingly, the 50-year-old subject of this case study undertook 60 weeks of regular AHIT. Successive cardiac MRI results demonstrate, for the first time, a decrease in MI scar with exercise and, alongside mounting evidence of high efficacy and low risk, suggests AHIT may be increasingly important in future prevention and reversing of disease and or amelioration of symptoms.

Akt1-mediated skeletal muscle growth attenuates cardiac dysfunction and remodeling after experimental myocardial infarction

BACKGROUND

It is appreciated that aerobic endurance exercise can attenuate unfavorable myocardial remodeling following myocardial infarction. In contrast, little is known about the effects of increasing skeletal muscle mass, typically achieved through resistance training, on this process. Here, we utilized transgenic (TG) mice that can induce the growth of functional skeletal muscle by switching Akt1 signaling in muscle fibers to assess the impact of glycolytic muscle growth on post-myocardial infarction cardiac remodeling.

METHODS AND RESULTS

Male-noninduced TG mice and their nontransgenic littermates (control) were subjected to left anterior coronary artery ligation. Two days after surgery, mice were provided doxycycline in their drinking water to activate Akt1 transgene expression in a skeletal muscle-specific manner. Myogenic Akt1 activation led to diminished left ventricular dilation and reduced contractile dysfunction compared with control mice. Improved cardiac function in Akt1 TG mice was coupled to diminished myocyte hypertrophy, decreased interstitial fibrosis, and increased capillary density. ELISA and protein array analyses demonstrated that serum levels of proangiogenic growth factors were upregulated in Akt1 TG mice compared with control mice. Cardiac eNOS was activated in Akt1 TG mice after myocardial infarction. The protective effect of skeletal muscle Akt activation on cardiac remodeling and systolic function was abolished by treatment with the eNOS inhibitor l-NAME.

CONCLUSIONS

Akt1-mediated skeletal muscle growth attenuates cardiac remodeling after myocardial infarction and is associated with an increased capillary density in the heart. This improvement appears to be mediated by skeletal muscle to cardiac communication, leading to activation of eNOS-signaling in the heart.

Long-term myocardial adaptations after cardiac rehabilitation in heart failure: a randomized six-year evaluation using magnetic resonance imaging

OBJECTIVE

To assess exercise capacity and left ventricular function using magnetic resonance imaging (MRI) among patients with chronic heart failure randomized to a residential rehabilitation programme at baseline and six years after participation.

DESIGN

Randomized controlled study.

SETTING

Residential cardiac rehabilitation centre and community hospital.

INTERVENTION

One month of intensive exercise and risk reduction therapy including educational sessions, a low-fat diet, and 2 hours of individually prescribed exercise daily. Control subjects received usual care. Subjects were evaluated at baseline, after completing the one-month residential programme and six years later.

SUBJECTS

From an original study group of 50, 16 patients (8 exercise, 8 controls) with chronic heart failure were alive and available for evaluation after six years.

MAIN MEASURES

Cardiopulmonary exercise test responses and ventricular size and function using MRI.

RESULTS

Peak Vo(2) was 20.0 and 12.4% higher after the rehabilitation programme and six years later, respectively, whereas minimal changes were observed among controls. Left ventricular mass and volumes tended to decrease among subjects in the exercise group, whereas left ventricular mass and volumes tended to increase among control subjects after six years. Ejection fraction increased approximately 20% in both groups.

CONCLUSION

Six years after participation in a concentrated residential rehabilitation programme, exercise capacity was preserved and no significant changes were observed in ventricular size or function. These findings provide further support for exercise rehabilitation in chronic heart failure.

Effects of progressive exercise during phase I cardiac rehabilitation on the heart rate variability of patients with acute myocardial infarction

PURPOSE

Heart rate variability (HRV) decreases after an acute myocardial infarction (AMI) due to changes in cardiac autonomic balance. The purpose of the present study, therefore, was to evaluate the effects of a progressive exercise protocol used in phase I cardiac rehabilitation on the HRV of patients with post-AMI.

MATERIAL AND METHODS

Thirty-seven patients who had been admitted to hospital with their first non-complicated AMI were studied. The treated group (TG, n=21, age=52±12 years) performed a 5-day programme of progressive exercise during phase I cardiac rehabilitation, while the control group (CG, n=16, age=54±11 years) performed only respiratory exercises. Instantaneous heart rate (HR) and RR interval were acquired by a HR monitor (Polar®S810i). HRV was analysed by frequency domain methods. Power spectral density was expressed as normalised units (nu) at low (LF) and high (HF) frequencies, and as LF/HF.

RESULTS

After 5 days of progressive exercise, the TG showed an increase in HFnu (35.9±19.5 to 65.19±25.4) and a decrease in LFnu and LF/HF (58.9±21.4 to 32.5±24.1; 3.12±4.0 to 1.0±1.5, respectively) in the resting position (p<0.05). No changes were observed in the CG.

CONCLUSIONS

A progressive physiotherapeutic exercise programme carried out during phase I cardiac rehabilitation, as supplement to clinical treatment increased vagal and decreased sympathetic cardiac modulation in patients with post-AMI.

Beneficial effects of exercise training after myocardial infarction require full eNOS expression

Exercise training attenuates left ventricular (LV) dysfunction after myocardial infarction (MI). It could be speculated that these effects of exercise are mediated by increased endothelial NO synthase (eNOS) activity. In the present study we tested the hypothesis that eNOS plays a critical role in the exercise-induced amelioration of LV dysfunction after MI. MI or sham was induced in eNOS(-/-), eNOS(+/-) and eNOS(+/+) mice. After 8 weeks of voluntary wheel running (approximately 7 km/day in all groups) or sedentary housing, global cardiac function was determined in vivo and (immuno)histochemistry was performed to assess cardiomyocyte size, fibrosis, capillary density and apoptosis in remote myocardium. At baseline eNOS(-/-) mice had higher mean aortic pressure compared to eNOS(+/-) and eNOS(+/+) mice, but had normal global cardiac function. MI resulted in marked LV remodeling, including cardiomyocyte hypertrophy and a reduction in capillary density, increased fibrosis and apoptosis, as well as LV systolic and diastolic dysfunction to the same extent in all genotypes. In eNOS(+/+) MI mice exercise abolished fibrosis and apoptosis in the remote myocardium, attenuated LV systolic dysfunction and ameliorated pulmonary congestion. These beneficial effects were lost in eNOS(+/-) and eNOS(-/-) mice, while LV systolic dysfunction and pulmonary congestion in eNOS(+/-) mice were exacerbated by exercise. In conclusion, the beneficial effects of exercise after MI on LV remodeling and dysfunction depend critically on endogenous eNOS. The observation that the lack of one eNOS allele is sufficient to negate all beneficial effects of exercise, strongly suggests that exercise depends on full eNOS expression.

Importance of strain imaging in cardiac rehabilitation

Cardiac rehabilitation improves the subjective condition of the patient; but are there associated structural and functional cardiac adaptations? The study group consisted of 39 patients with an inferior infarction and 21 patients with an anterior infarction, treated by surgical revascularization followed by 4 months of cardiac rehabilitation. Maximal exercise testing and Doppler echocardiography were performed before and after the rehabilitation program. Performance capacity was significantly improved after cardiac rehabilitation, but left ventricular function remained unchanged on Doppler imaging. Only by analyzing the subgroups using strain imaging significant differences were noted after cardiac rehabilitation: patients with an inferior infarction exhibited improved strain values in the anterior wall; those with an anterior infarction had improved strain values in the inferior wall. Strain values in the infarcted regions were worse after cardiac rehabilitation. Strain imaging indicated that cardiac rehabilitation could bring about improvements in cardiac function exclusively in the healthy non-infarcted myocardium, while there were signs of further deterioration of myocardial function in the highly ischemic zones.

Prior exercise improves survival, infarct healing, and left ventricular function after myocardial infarction

We investigated the effects of voluntary wheel running before an acute myocardial infarction (MI) on survival, left ventricular (LV) remodeling and dysfunction and whether exercise before and after MI provides superior protection compared with either exercise intervention alone. After 2 wk of voluntary wheel running or sedentary housing, MI was induced in C57Bl/6 mice, after which exercise was stopped (EX-MI-SED and SED-MI-SED groups, where EX is exercise and SED is sedentary) or continued (EX-MI-EX and SED-MI-EX groups) for a period of 8 wk. Exercise after MI in SED-MI-EX mice had no effect on survival, the area of infarction, and global LV remodeling, but attenuated fibrosis and apoptosis in the remote myocardium and blunted LV dysfunction and pulmonary congestion compared with SED-MI-SED mice. Exercise before MI in both EX-MI-SED and EX-MI-EX mice decreased post-MI mortality compared with both SED-MI-SED and SED-MI-EX mice. Furthermore, in both pre-MI exercise groups, the infarct area was thicker, whereas interstitial fibrosis and apoptosis in the remote LV myocardium were blunted. In contrast, the ameliorating effects of either pre-MI or post-MI exercise alone on LV dysfunction were lost in EX-MI-EX mice, which may in part be related to the increased daily exercise distance in the first week post-MI in EX-MI-EX versus SED-MI-EX mice. In conclusion, exercise before or after MI blunted LV dysfunction, whereas only exercise before MI improved survival. These findings suggest that even when regular physical activity fails to prevent an acute MI, it can still act to improve cardiac function and survival after MI.

Absence of Exercise Capacity Improvement After Exercise Training Program

Background— Exercise training is established as adjuvant therapy for chronic heart failure, but the prognostic value of improvement in exercise capacity after exercise training has never been evaluated.

Methods and Results— In this prospective bicentric study, all chronic heart failure patients with left ventricular ejection fraction <45% who underwent an exercise training program in a cardiac rehabilitation center between January 2004 and September 2006 were consecutively included. Improvement in exercise capacity was assessed by change in peak oxygen consumption (δPV o 2 ) and in PV o 2 expressed as a percentage of predicted PV o 2 (δ%PPV o 2 ) measured before and after the training program. We included 155 patients (54�12 years old, male 81%, left ventricular ejection fraction=29.5�7.1%). Patients underwent 20 (10–30) training sessions. PV o 2 and %PPV o 2 were significantly increased after the training program (14% and 13%, respectively, P <0.001 for both). After 16�6 months follow-up, 27 patients had a cardiac event (death [n=12], cardiac transplantation [n=5], hospitalization for acute heart failure [n=10]). Univariate analysis revealed that among 17 significant predictors of cardiac events, the 2 more powerful ones were level of B-type natriuretic peptide at baseline ( P <0.0001) and improvement in exercise capacity as assessed by δPV o 2 and δ%PPV o 2 ( P <0.0001). Multivariate analysis revealed B-type natriuretic peptide level and δ%PPV o 2 as only independent predictive factors of outcome ( P =0.01). The risk ratio of cardiac events for nonresponse versus response to the training program (defined as median δ%PPV o 2 <6%) was 8.2 ( P =0.0006).

Conclusions— Among patients with chronic heart failure, the lack of improvement in exercise capacity after an exercise training program has strong prognostic value for adverse cardiac events independent of classical predictive factors such as left ventricular ejection fraction, New York Heart Association class, and B-type natriuretic peptide level.

Left ventricular remodelling in patients with moderate systolic dysfunction after myocardial infarction: favourable effects of exercise training and predictive role of N-terminal pro-brain natriuretic peptide

AIMS

To investigate the effects of exercise training (ET) on left ventricular (LV) volumes, cardiopulmonary functional capacity and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels in postinfarction patients with moderate LV dysfunction.

METHODS

Sixty-one postinfarction patients were randomized into two groups: group T [n=30, LV ejection fraction (EF) 41.6+/-11.3%, mean+/-SD] entered a 6-month ET programme, whereas group C (n=31, EF 42.0+/-7.6%, P=NS) did not. NT-proBNP assay, Doppler-echocardiography and cardiopulmonary exercise test were performed upon enrolment and at sixth months.

RESULTS

At sixth months, trained patients showed an improvement in workload (+26%, P<0.001), Vo2peak (+31%, P<0.001), LV end-diastolic volume index (LVEDVI; -9%, P<0.001), a reduction in NT-proBNP (-71%, P<0.001) and a significant correlation between changes in NT-proBNP and in LVEDVI (r=0.858, P<0.001). Baseline NT-proBNP correlated with changes in LVEDVI in both trained (r=0.673, P<0.001) and untrained (r=0.623, P<0.001) patients. Group C showed unfavourable LVEDVI dilation (+8%, P<0.001; T vs. C group, P<0.001) and a smaller reduction in NT-proBNP (-40%, P<0.001; T vs. C group, P<0.001).

CONCLUSIONS

Six month ET induced a favourable LV remodelling and a marked fall in NT-proBNP that could predict LV remodelling in postinfarction patients with moderate LV dysfunction.

Early exercise training normalizes myofilament function and attenuates left ventricular pump dysfunction in mice with a large myocardial infarction

The extent and mechanism of the cardiac benefit of early exercise training following myocardial infarction (MI) is incompletely understood, but may involve blunting of abnormalities in Ca(2+)-handling and myofilament function. Consequently, we investigated the effects of 8-weeks of voluntary exercise, started early after a large MI, on left ventricular (LV) remodeling and dysfunction in the mouse. Exercise had no effect on survival, MI size or LV dimensions, but improved LV fractional shortening from 8+/-1 to 12+/-1%, and LVdP/dt(P30) from 5295+/-207 to 5794+/-207 mm Hg/s (both P<0.05), and reduced pulmonary congestion. These global effects of exercise were associated with normalization of the MI-induced increase in myofilament Ca(2+)-sensitivity (DeltapCa(50)=0.037). This effect of exercise was PKA-mediated and likely because of improved beta(1)-adrenergic signaling, as suggested by the increased beta(1)-adrenoceptor protein (48%) and cAMP levels (36%; all P<0.05). Exercise prevented the MI-induced decreased maximum force generating capacity of skinned cardiomyocytes (F(max) increased from 14.3+/-0.7 to 18.3+/-0.8 kN/m(2) P<0.05), which was associated with enhanced shortening of unloaded intact cardiomyocytes (from 4.1+/-0.3 to 7.0+/-0.6%; P<0.05). Furthermore, exercise reduced diastolic Ca(2+)-concentrations (by approximately 30%, P<0.05) despite the unchanged SERCA2a and PLB expression and PLB phosphorylation status. Importantly, exercise had no effect on Ca(2+)-transient amplitude, indicating that the improved LV and cardiomyocyte shortening were principally because of improved myofilament function. In conclusion, early exercise in mice after a large MI has no effect on LV remodeling, but attenuates global LV dysfunction. The latter can be explained by the exercise-induced improvement of myofilament function.

Are Cardiac Events During Exercise Therapy for Heart Failure Predictable From the Baseline Variables?

BACKGROUND

Exercise training (ET) is an emerging therapy for chronic heart failure, but the baseline patient characteristics for predicting cardiac events (CEs) during the course of ET remain unknown.

METHODS AND RESULTS

Of the 111 stable heart failure patients who participated in a 3-month ET program, 6 withdrew from the program for cardiac reasons and 9 had transient interruptions in the program because of CEs. The baseline clinical characteristics of these 15 patients (CE group) and the remaining 96 patients (No-CE group) were compared. Compared with the No-CE group, the CE group had a significantly higher prevalence of pacemaker/implantable cardioverter-defibrillators, larger left ventricular end-diastolic diameter (LVEDDs), lower peak oxygen uptake, greater ventilation drive, and higher plasma brain natriuretic peptide concentration at baseline. Multivariate logistic regression analysis showed that a larger LVEDD was a significant predictor of the occurrence of a transient interruption to or permanent withdrawal from the ET program because of CEs. Receiver operating characteristic curve analysis demonstrated that an LVEDD > or = 65 mm had a sensitivity of 93% and specificity of 48% in predicting CEs.

CONCLUSIONS

Patients with a large LVEDD (> or = 65 mm) at baseline should be monitored carefully during the course of an ET program.

Reduction of N terminal-pro-brain (B-type) natriuretic peptide levels with exercise-based cardiac rehabilitation in patients with left ventricular dysfunction after myocardial infarction

INTRODUCTION

N-terminal-pro-brain (B-type) natriuretic peptide (NT-pro-BNP) is a peptide hormone released from ventricles in response to myocyte stretch. The aim of the study was to investigate the influence of exercise training on plasma NT-pro-BNP to verify if this parameter could be used as a biological marker of left ventricular remodelling in myocardial infarction patients undergoing an exercise training programme.

METHODS

Forty-four patients after myocardial infarction were enrolled into a cardiac rehabilitation programme, and were randomized in two groups of 22 patients each. Group A patients followed a 3-month exercise training programme, while group B patients received only routine recommendations. All patients underwent NT-pro-BNP assay, and cardiopulmonary exercise test before hospital discharge and after 3 months.

RESULTS

In Group A, exercise training reduced NT-pro-BNP levels (from 1498+/-438 to 470+/-375 pg/ml, P=0.0026), increased maximal (VO2peak+4.3+/-2.9 ml/kg per min, P<0.001; Powermax+38+/-7, P<0.001) exercise parameters and work efficiency (Powermax/VO2peak+1.3+/-0.4 Power/ml per kg per min, P<0.001); there was also an inverse correlation between changes in NT-pro-BNP levels and in VO2peak (r=-0.72, P<0.001), E-wave (r=-0.51, P<0.001) and E/A ratio (r=0.59, P<0.001). In group B, at 3 months, no changes were observed in NT-pro-BNP levels, exercise and echocardiographic parameters.

CONCLUSION

Three months exercise training in patients with moderate left ventricular systolic dysfunction after myocardial infarction induced a reduction in NT-pro-BNP levels, an improvement of exercise capacity and early left ventricular diastolic filling, without negative left ventricular remodelling. Whether the reduction of NT-pro-BNP levels could be useful as a surrogate marker of favourable left ventricular remodelling at a later follow-up remains to be further explored.

Effects of Exercise Training on Left Ventricular Function Evaluated by the Tei Index in Patients With Myocardial Infarction

BACKGROUND

This study investigated the influence of exercise training on left ventricular (LV) function in patients with acute myocardial infarction (AMI) using a new index of cardiac function, the Tei index.

METHODS AND RESULTS

The study enrolled 53 consecutive patients (36 males, 17 females; mean age: 65+/-10 years) with AMI. Exercise training was performed for 6 months; peak VO2 and the Tei index were measured at the start of the cardiac rehabilitation program and 1, 3, and 6 months later. The peak VO2 improved from 14.3+/-3.3 to 18.5+/-5.2 ml.min -1.kg-1 after 6 months (p<0.01). Although there were no significant changes in LV ejection fraction over the 6 months, the Tei index improved from 0.50+/-0.18 to 0.41+/-0.19 (p<0.05). When the DeltaTei index was compared among the 3 groups classified by the Tei index at baseline, the values improved in the groups with high/slightly high values compared with the normal group.

CONCLUSION

Both cardiac function, as evaluated by the Tei index, and exercise capacity improved after exercise training in patients with AMI. The greater improvement was seen in the population with the higher value (lower cardiac function) according to this index.

Assessment of Quality of Life With 5 Different Scales in Patients Participating in Comprehensive Cardiac Rehabilitation After Acute Myocardial Infarction

BACKGROUND

Measures assessing quality of life (QOL) in patients participating in comprehensive cardiac rehabilitation (CCR) have not been established in Japan.

METHODS AND RESULTS

To compare different types of QOL scales and to determine the impact of CCR on QOL in Japanese cardiac patients, 5 different types of questionnaires were assessed in 44 patients participating in CCR after acute myocardial infarction (AMI). After 3-month CCR, peak oxygen uptake (PVO2, p<0.01), Sickness Impact Profile (SIP) total score (p<0.05) and physical function-related QOL scores (Specific Activity Scale (SAS), p<0.01; SIP physical score, p<0.01) significantly improved, whereas psychosocial/mental aspect-related QOL scores (Ministry of Health and Welfare (MHW)-QOL score, SIP psychosocial score, State-Trait Anxiety Inventory, Self-rating Depression Scale) did not change on the average. However, patients with low PVO2 (<21.7 ml.min-1.kg-1) showed significant improvements in all scores after CCR, whereas patients with preserved exercise capacity showed improvements only in physical function-related scores (SAS and physical SIP). Furthermore, patients with anxiety and depression showed significant improvements in these respective measures after CCR.

CONCLUSION

In patients with AMI, physical function-related QOL scores improve after a 3-month CCR program, but psychosocial/mental aspect-related QOL scores improve only in those with impaired exercise tolerance or anxiety/depression. Thus, changes in QOL after CCR depend on type of QOL scale used and the baseline status of the patient. In addition, in Japanese cardiac patients MHW-QOL mainly reflects psychosocial/mental aspect-related QOL, as well as overall QOL.

Exercise training for patients with heart failure: a systematic review of factors that improve mortality and morbidity

PURPOSE

To determine the efficacy of exercise training and its effects on outcomes in patients with heart failure.

METHODS

MEDLINE, Medscape, and the Cochrane Controlled Trials Registry were searched for trials of exercise training in heart failure patients. Data relating to training protocol, exercise capacity, and outcome measures were extracted and reviewed.

RESULTS

A total of 81 studies were identified: 30 randomized controlled trials, five nonrandomized controlled trials, nine randomized crossover trials, and 37 longitudinal cohort studies. Exercise training was performed in 2387 patients. The average increment in peak oxygen consumption was 17% in 57 studies that measured oxygen consumption directly, 17% in 40 studies of aerobic training, 9% in three studies that only used strength training, 15% in 13 studies of combined aerobic and strength training, and 16% in the one study on inspiratory training. There were no reports of deaths that were directly related to exercise during more than 60,000 patient-hours of exercise training. During the training and follow-up periods of the randomized controlled trials, there were 56 combined (deaths or adverse events) events in the exercise groups and 75 combined events in the control groups (odds ratio [OR] = 0.98; 95% confidence interval [CI]: 0.61 to 1.32; P = 0.60). During this same period, 26 exercising and 41 nonexercising subjects died (OR = 0.71; 95% CI: 0.37 to 1.02; P = 0.06).

CONCLUSION

Exercise training is safe and effective in patients with heart failure. The risk of adverse events may be reduced, but further studies are required to determine whether there is any mortality benefit.

Predictors of Left Ventricular Remodeling in Patients With Acute Myocardial Infarction Participating in Cardiac Rehabilitation-Brain Natriuretic Peptide and Anterior Infarction-

BACKGROUND

This study was designed to determine the factors influencing the development of left ventricular (LV) remodeling in patients participating in a comprehensive cardiac rehabilitation (CR) program after acute myocardial infarction (AMI), with special reference to exercise intensity and frequency.

METHODS AND RESULTS

A total of 72 patients with AMI participated in CR consisting of exercise training of moderate intensity (heart rate reserve 40-60%) and education for 12 weeks. Plasma concentration of brain natriuretic peptide (BNP) was measured at the beginning and the end of CR. Echocardiography was performed before and 1 year after CR. An increase in LV end-diastolic dimension (delta-LVDd) from baseline was used as an index of remodeling. Delta-LVDd was significantly greater in patients with an anterior AMI than with other infarct locations (p<0.05) and correlated significantly with baseline BNP concentration (p<0.05). Delta-LVDd >5 mm occurred exclusively in patients with baseline BNP >150 pg/ml. Variables representing the intensity and frequency of exercise training did not correlate with delta-LVDd.

CONCLUSIONS

In patients with AMI participating in CR, those having both anterior infarction and baseline BNP concentration >150 pg/ml are at high risk for subsequent LV remodeling, whereas neither exercise intensity nor participation frequency in CR appears to be associated with LV remodeling.