Effect of High-Intensity Interval Training in De Novo Heart Transplant Recipients in Scandinavia

Prevention and rehabilitation after heart transplantation: A clinical consensus statement of the European Association of Preventive Cardiology, Heart Failure Association of the ESC, and the European Cardio Thoracic Transplant Association, a section of ESOT

Little is known either about either physical activity patterns, or other lifestyle-related prevention measures in heart transplantation (HTx) recipients. The history of HTx started more than 50 years ago but there are still no guidelines or position papers highlighting the features of prevention and rehabilitation after HTx. The aims of this scientific statement are (i) to explain the importance of prevention and rehabilitation after HTx, and (ii) to promote the factors (modifiable/non-modifiable) that should be addressed after HTx to improve patients' physical capacity, quality of life and survival. All HTx team members have their role to play in the care of these patients and multidisciplinary prevention and rehabilitation programmes designed for transplant recipients. HTx recipients are clearly not healthy disease-free subjects yet they also significantly differ from heart failure patients or those who are supported with mechanical circulatory support. Therefore, prevention and rehabilitation after HTx both need to be specifically tailored to this patient population and be multidisciplinary in nature. Prevention and rehabilitation programmes should be initiated early after HTx and continued during the entire post-transplant journey. This clinical consensus.

Prevention and Rehabilitation After Heart Transplantation: A Clinical Consensus Statement of the European Association of Preventive Cardiology, Heart Failure Association of the ESC, and the European Cardio Thoracic Transplant Association, a Section of ESOT

Little is known either about either physical activity patterns, or other lifestyle-related prevention measures in heart transplantation (HTx) recipients. The history of HTx started more than 50 years ago but there are still no guidelines or position papers highlighting the features of prevention and rehabilitation after HTx. The aims of this scientific statement are (i) to explain the importance of prevention and rehabilitation after HTx, and (ii) to promote the factors (modifiable/non-modifiable) that should be addressed after HTx to improve patients' physical capacity, quality of life and survival. All HTx team members have their role to play in the care of these patients and multidisciplinary prevention and rehabilitation programmes designed for transplant recipients. HTx recipients are clearly not healthy disease-free subjects yet they also significantly differ from heart failure patients or those who are supported with mechanical circulatory support. Therefore, prevention and rehabilitation after HTx both need to be specifically tailored to this patient population and be multidisciplinary in nature. Prevention and rehabilitation programmes should be initiated early after HTx and continued during the entire post-transplant journey. This clinical consensus statement focuses on the importance and the characteristics of prevention and rehabilitation designed for HTx recipients.

A Review of High-Intensity Interval Training in Heart Transplant Recipients: Current Knowledge and Future Perspectives

OBJECTIVE

This review reports how exercise-based rehabilitation strategies have developed over the past decades, and it specifically focuses on the effectiveness, safety, and implementation of high-intensity interval training (HIIT). It provides an overview of the historical progression, main research findings, and considerations surrounding HIIT as the preferred exercise modality for recipients of heart transplant (HTx).

REVIEW METHODS

The review includes a timeline of studies spanning from 1976-2023. The 2017 Cochrane systematic review on exercise-based cardiac rehabilitation in recipients of HTx serves as the main knowledge base (≥2015). Additionally, literature searches in PubMed/Medline and ClinicalTrials.gov have been performed, and all reviews and studies reporting the effects of moderate- to high-intensity exercise in recipients of HTx, published in 2015 or later have been screened.

SUMMARY

High-intensity interval training has gained prominence as an effective exercise intervention for recipients of HTx, demonstrated by an accumulation of performed studies in the past decade, although implementation in clinical practice remains limited. Early restrictions on HIIT in HTx recipients lacked evidence-based support, and recent research challenges these previous restrictions. High-intensity interval training results in greater improvements and benefits compared with moderate-intensity continuous training in the majority of studies. While HIIT is now regarded as generally suitable on a group level, individual assessment is still advised. The impact of HIIT involves reinnervation and central and peripheral adaptations to exercise, with variations in recipent responses, especially between de novo and maintenance recipients, and also between younger and older recipients. Long-term effects and mechanisms behind the HIIT effect warrant further investigation, as well as a focus on optimized HIIT protocols and exercise benefits.

Correlation between peripheral endothelial function, oxygen consumption and ventilatory efficiency in heart transplantation recipients

BACKGROUND

Endothelial dysfunction and peak oxygen uptake (VO2peak) are also predictors of increased risk of cardiovascular events in heart transplantation (HTx) recipients. The preservation of endothelial function may contribute to exercise tolerance.

OBJECTIVE

To investigate the correlation between peripheral endothelial function and exercise tolerance through VO2peak and ventilation to carbon dioxide production slope (VE / VCO2 slope) in HTx recipients.

METHODS

A pilot cross-sectional study was conducted with adult individuals aged 18-65 years, HTx ≥ six months after surgery, who had a stable medical condition and no changes over the last three months of immunosuppressive treatment. The patients underwent an assessment of endothelial function through PAT (EndoPAT-2000®) and performed a cardiopulmonary exercise test (CPET).

RESULTS

A total of 41% of the studied population presented endothelial dysfunction. The individuals were divided into two groups: the endothelial dysfunction (GED; n=9) group and the normal endothelial function (GNEF; n=13) group according to the logarithm of the reactive hyperemia index (LnRHI). There was a positive and moderate correlation between the LnRHI and VO2 peak (r=0.659, p=0.013) and a negative and moderate correlation between the LnRHI and VE/VCO2 slope (r= -0.686, p= 0.009) in the GNEF. However, no significant correlations were found in the GED.

CONCLUSION

The results showed that the preservation of peripheral endothelial function is significantly correlated with an increase in exercise tolerance in individuals after HTx. These findings bring important considerations for cardiovascular risk prevention and emphasize that therapeutic strategies with physical training programs must be implemented early.

Rates of compliance and adherence to high-intensity interval training: a systematic review and Meta-analyses

BACKGROUND

To determine rates of compliance (i.e., supervised intervention attendance) and adherence (i.e., unsupervised physical activity completion) to high-intensity interval training (HIIT) among insufficiently active adults and adults with a medical condition, and determine whether compliance and adherence rates were different between HIIT and moderate-intensity continuous training (MICT).

METHODS

Articles on adults in a HIIT intervention and who were either insufficiently active or had a medical condition were included. MEDLINE, EMBASE, PsychINFO, SPORTDiscus, CINAHL, and Web of Science were searched. Article screening and data extraction were completed by two independent reviewers. Risk of bias was assessed using RoB 2.0 or ROBINS-I. Meta-analyses were conducted to discern differences in compliance and adherence between HIIT vs. MICT. Sensitivity analyses, publication bias, sub-group analyses, and quality appraisal were conducted for each meta-analysis.

RESULTS

One hundred eighty-eight unique studies were included (n = 8928 participants). Compliance to HIIT interventions averaged 89.4% (SD:11.8%), while adherence to HIIT averaged 63% (SD: 21.1%). Compliance and adherence to MICT averaged 92.5% (SD:10.6%) and 68.2% (SD:16.2%), respectively. Based on 65 studies included in the meta-analysis, compliance rates were not different between supervised HIIT and MICT interventions [Hedge's g = 0.015 (95%CI: - 0.088-0.118), p = .78]. Results were robust and low risk of publication bias was detected. No differences were detected based on sub-group analyses comparing medical conditions or risk of bias of studies. Quality of the evidence was rated as moderate over concerns in the directness of the evidence. Based on 10 studies, adherence rates were not different between unsupervised HIIT and MICT interventions [Hedge's g = - 0.313 (95%CI: - 0.681-0.056), p = .096]. Sub-group analysis points to differences in adherence rates dependent on the method of outcome measurement. Adherence results should be interpreted with caution due to very low quality of evidence.

CONCLUSIONS

Compliance to HIIT and MICT was high among insufficiently active adults and adults with a medical condition. Adherence to HIIT and MICT was relatively moderate, although there was high heterogeneity and very low quality of evidence. Further research should take into consideration exercise protocols employed, methods of outcome measurement, and measurement timepoints.

REGISTRATION

This review was registered in the PROSPERO database and given the identifier CRD42019103313.

Exploring the Promise of Telemedicine Exercise Interventions in Children and Adolescents With Congenital Heart Disease

Youth with congenital heart disease (CHD) have reduced exercise capacity via various physical and psychosocial mechanisms. In addition to limited physiologic exercise capacity, these patients experience lower levels of physical activity, physical activity self-efficacy, health-related quality of life, and endothelial function. The study of exercise interventions and cardiac rehabilitation programs in pediatric CHD populations remains limited, particularly home-based interventions that incorporate real-time physiologic monitoring. Home-based interventions provide improved access and convenience to patients. This is principally important for patients from geographically disperse regions who receive their care at centralized subspecialty centres, as is the case for Canadian pediatric cardiac care. These programs, however, have traditionally not permitted the supervision of safety, technique, and adherence that are afforded by hospital/facility-based programs. As such, telemedicine is an important evolving area that combines the benefits of traditional home and facility-based cardiac rehabilitation. An additional key area lacking study surrounds the types of exercise interventions in youth with CHD. To date, interventions have often centred around moderate-intensity continuous exercise. High-intensity interval training might offer superior cardiorespiratory advantages but remains understudied in the CHD population. In this review, we highlight the existing evidence basis for exercise interventions in youth with CHD, explore the promise of incorporating telemedicine home-based solutions, and highlight key knowledge gaps. To address identified knowledge gaps, we are undertaking a 12-week randomized crossover trial of a home-based telemedicine high-intensity interval training intervention in youth with repaired moderate-severe CHD using a video game-linked cycle ergometer (known as the MedBIKE; https://spaces.facsci.ualberta.ca/ahci/projects/medical-projects/remote-rehab-bike-projects).

Effect of Exercise Training on Peak Aerobic Power After Heart Transplantation: A Brief Review

Heart transplantation (HTP) is a life-saving therapy for selected individuals with end-stage refractory heart failure. Despite improvements in quality of life and survival, HTP recipients' peak aerobic power (peak VO2) remains up to 50% lower than age-matched healthy control subjects owing to abnormal cardiovascular and skeletal muscle function. Currently, little is known regarding the effect of exercise training (ET) to improve peak VO2 after HTP. This brief review aims to summarise existing evidence regarding the role of ET on peak VO2 and its determinants, highlights the upper limits of endurance performance in highly trained HTP athletes, and identifies areas for future HTP exercise rehabilitation research.

Scuba diving after a heart transplant: excessive daring or calculable risk?

Over the past 50 years, outcomes after heart transplantation (HTX) have continuously and significantly improved. In the meantime, many heart transplant recipients live almost normal lives with only a few limitations. In some cases, even activities that actually seemed unreasonable for these patients turn out to be feasible. This article describes the encouraging example of a patient returning to recreational scuba diving after HTX. So far, there were no scientific experiences documented in this area. We worked out the special hemodynamic features and the corresponding risks of this sport for heart transplant recipients in an interdisciplinary manner and evaluated them using the patient as an example. The results show that today, with the appropriate physical condition and compliance with safety measures, a wide range of activities, including scuba diving, are possible again after HTX. They illustrate again the significant development and the enormous potential of this therapy option, which is unfortunately only available to a limited extent.NEW & NOTEWORTHY Example for shared decision-making process for tricky questions: First scientific publication about heart transplantation (HTX)-recipient restarting scuba diving. As exercise physiology after HTX combined with specific diving medicine aspects is challenging, we formed a multidisciplinary team to identify, evaluate, and mitigate the risks involved. The results show that today, with the appropriate physical condition and compliance with safety measures, a wide range of activities are possible again after HTX.

2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease" provides an update to and consolidates new evidence since the "2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease" and the corresponding "2014 ACC/AHA/AATS/PCNA/SCAI/STS Focused Update of the Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease."

METHODS

A comprehensive literature search was conducted from September 2021 to May 2022. Clinical studies, systematic reviews and meta-analyses, and other evidence conducted on human participants were identified that were published in English from MEDLINE (through PubMed), EMBASE, the Cochrane Library, Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline.

STRUCTURE

This guideline provides an evidenced-based and patient-centered approach to management of patients with chronic coronary disease, considering social determinants of health and incorporating the principles of shared decision-making and team-based care. Relevant topics include general approaches to treatment decisions, guideline-directed management and therapy to reduce symptoms and future cardiovascular events, decision-making pertaining to revascularization in patients with chronic coronary disease, recommendations for management in special populations, patient follow-up and monitoring, evidence gaps, and areas in need of future research. Where applicable, and based on availability of cost-effectiveness data, cost-value recommendations are also provided for clinicians. Many recommendations from previously published guidelines have been updated with new evidence, and new recommendations have been created when supported by published data.

2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease" provides an update to and consolidates new evidence since the "2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease" and the corresponding "2014 ACC/AHA/AATS/PCNA/SCAI/STS Focused Update of the Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease."

METHODS

A comprehensive literature search was conducted from September 2021 to May 2022. Clinical studies, systematic reviews and meta-analyses, and other evidence conducted on human participants were identified that were published in English from MEDLINE (through PubMed), EMBASE, the Cochrane Library, Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline.

STRUCTURE

This guideline provides an evidenced-based and patient-centered approach to management of patients with chronic coronary disease, considering social determinants of health and incorporating the principles of shared decision-making and team-based care. Relevant topics include general approaches to treatment decisions, guideline-directed management and therapy to reduce symptoms and future cardiovascular events, decision-making pertaining to revascularization in patients with chronic coronary disease, recommendations for management in special populations, patient follow-up and monitoring, evidence gaps, and areas in need of future research. Where applicable, and based on availability of cost-effectiveness data, cost-value recommendations are also provided for clinicians. Many recommendations from previously published guidelines have been updated with new evidence, and new recommendations have been created when supported by published data.

High-intensity interval training versus moderate-intensity continuous training on patient quality of life in cardiovascular disease: a systematic review and meta-analysis

This systematic review and meta-analysis aimed to compare the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on the quality of life (QOL) and mental health (MH) of patients with cardiovascular disease (CVDs). Web of Science, Medline, Embase, Cochrane (CENTRAL), CINAHL, China National Knowledge Infrastructure, Wanfang, and China Science and Technology Journal databases were searched from their date of establishment to July, 2023. A total of 5798 articles were screened, of which 25 were included according to the eligibility criteria. The weighted mean difference (WMD) and standardized mean difference (SMD) were used to analyze data from the same and different indicator categories, respectively. The fixed-effects model (FE) or random-effects model (RE) combined data based on the between-study heterogeneity. There were no statistically significant differences regarding QOL, physical component summary (PCS), mental component summary (MCS), and MH, including depression and anxiety levels, between the HIIT and MICT groups [SMD = 0.21, 95% confidence interval (CI)  - 0.18-0.61, Z = 1.06, P = 0.290; SMD = 0.10, 95% CI  - 0.03-0.23, Z = 1.52, P = 0.128; SMD = 0.07, 95% CI  - 0.05-0.20, Z = 1.13, P = 0.25; SMD = - 0.08, 95% CI  - 0.40-0.25, Z = - 0.46, P = 0.646; WMD = 0.14. 95% CI  - 0.56-0.84, Z = 0.39, P = 0.694, respectively]. HIIT significantly improved PCS in the coronary artery disease (CAD) population subgroup relative to MICT. HIIT was also significantly superior to MICT for physical role, vitality, and social function. We conclude that HIIT and MICT have similar effects on QOL and MH in patients with CVD, while HIIT is favorable for improving patients' self-perceived physiological functioning based on their status and social adjustment, and this effect is more significant in patients with CAD.

Evaluating a Telemedicine Video Game-Linked High-Intensity Interval Training Exercise Programme in Paediatric Heart Transplant Recipients

Paediatric heart transplant recipients (HTRs) have reduced exercise capacity, physical activity (PA), health-related quality of life (HRQoL), and self-efficacy towards PA. Exercise interventions have demonstrated improvements in exercise capacity and functional status in adult HTRs, with a specific emerging interest in the role of high-intensity interval training (HIIT). Studies of exercise interventions in paediatric HTRs have been limited and nonrandomized to date. HIIT has not yet been evaluated in paediatric HTRs. We thus seek to evaluate the safety and feasibility of a randomized crossover trial of a 12-week, home-based, video game-linked HIIT intervention using a cycle ergometer with telemedicine and remote physiological monitoring capabilities (MedBIKE) in paediatric HTRs. The secondary objective is to evaluate the impact of the intervention on (1) exercise capacity, (2) PA, (3) HRQoL and self-efficacy towards PA, and (4) sustained changes in secondary outcomes at 6 and 12 months after intervention. After a baseline assessment of the secondary outcomes, participants will be randomized to receive the MedBIKE intervention (12 weeks, 36 sessions) or usual care. After the intervention and a repeated assessment, all participants will cross over. Follow-up assessments will be administered at 6 and 12 months after the MedBIKE intervention. We anticipate that the MedBIKE intervention will be feasible and safely yield sustained improvements in exercise capacity, PA, HRQoL, and self-efficacy towards PA in paediatric HTRs. This study will serve as the foundation for a larger, multicentre randomized crossover trial and will help inform exercise rehabilitation programmes for paediatric HTRs.

Effects of high-intensity interval training on cardiac remodelling, function and coronary microcirculation in de novo heart transplant patients: a substudy of the HITTS randomised controlled trial

Objectives

High-intensity interval training (HIT) improves peak oxygen consumption (VO2peak) in de novo heart transplant (HTx) recipients. It remains unclear whether this improvement early after HTx is solely dependent on peripheral adaptations, or due to a linked chain of central and peripheral adaptations. The objective of this study was to determine whether HIT results in structural and functional adaptations in the cardiovascular system.

Methods

Eighty-one de novo HTx recipients were randomly assigned to participate in either 9 months of supervised HIT or standard care exercise-based rehabilitation. Cardiac function was assessed by echocardiogram and the coronary microcirculation with the index of microcirculatory resistance (IMR) at baseline and 12 months after HTx.

Results

Cardiac function as assessed by global longitudinal strain was significantly better in the HIT group than in the standard care group (16.3±1.2% vs 15.6±2.2%, respectively, treatment effect = -1.1% (95% CI -2.0% to -0.2%), p=0.02), as was the end-diastolic volume (128.5±20.8 mL vs 123.4±15.5 mL, respectively, treatment effect=4.9 mL (95% CI 0.5 to 9.2 mL), p=0.03). There was a non-significant tendency for IMR to indicate improved microcirculatory function (13.8±8.0 vs 16.8±12.0, respectively, treatment effect = -4.3 (95% CI -9.1 to 0.6), p=0.08).

Conclusion

When initiated early after HTx, HIT leads to both structural and functional cardiovascular adaptations.

Trial registration number

NCT01796379.

Effectiveness of Exercise-Based Cardiac Rehabilitation for Heart Transplant Recipients: A Systematic Review and Meta-Analysis

Background:

Heart Transplant (HTx) is the ultimate chance of life for end stage Heart Failure (HF). Exercise training has consistently shown the potential to improve functional capacity in various chronic heart diseases. Still, the evidence in HTx recipients is scarcer. This study aims to systematically review the literature to evaluate the effectiveness and safety of Exercise-based Cardiac Rehabilitation (EBCR) in HTx recipients and to identify possible moderators of success.

Methods:

We conducted a systematic review and meta-analysis of randomized controlled trials on the effect and safety of EBCR in adult HTx recipients. The primary outcome was functional capacity, measured by Peak Oxygen Uptake (pVO2). We searched CENTRAL, MEDLINE, Embase, Scopus, and Web of Knowledge databases until December 2020, reviewed references of relevant articles and contacted experts. Usual care (UC), the different dosages of exercise regimens and alternative settings were allowed as comparators. A quantitative synthesis of evidence was performed using random-effects meta-analyses.

Results:

A total of 11 studies with 404 patients were included. Nine studies comprising 306 patients compared EBCR with usual care. They showed that EBCR improved pVO2 compared to usual care (Mean Difference [MD] 3.03 mL/kg/min, 95% CI [2.28-3.77]; I² = 32%). In the subgroup analysis, including length of intervention and timing of enrollment after HTx, no significant moderator was found. Two trials, with 98 patients total, compared High Intensity Interval Training (HIIT) and Moderate Intensity Continuous Training (MICT). HIIT attained a significant edge over MICT (MD 2.23 mL/kg/min, 95% CI [1.79-2.67]; I² = 0%). No major adverse events associated with EBCR were reported.

Conclusion:

We found moderate quality evidence suggesting EBCR has a significant benefit on functional capacity improvement HTx recipients at the short-term. HIIT showed superiority when compared to MICT. Research focusing long term outcomes and standardized protocols are needed to improve evidence on EBCR effectiveness.

Early Cardiopulmonary Fitness after Heart Transplantation as a Determinant of Post-Transplant Survival

BACKGROUND

Decreased peak oxygen consumption during exercise (peak Vo₂) is a well-established prognostic marker for mortality in ambulatory heart failure. After heart transplantation, the utility of peak Vo₂ as a marker of post-transplant survival is not well established.

METHODS AND RESULTS

We performed a retrospective analysis of adult heart transplant recipients at the Hospital of the University of Pennsylvania who underwent cardiopulmonary exercise testing within a year of transplant between the years 2000 to 2011. Using time-to-event models, we analyzed the hazard of mortality over nearly two decades of follow-up as a function of post-transplant percent predicted peak Vo₂ (%Vo₂). A total of 235 patients met inclusion criteria. The median post-transplant %Vo₂ was 49% (IQR 42 to 60). Each standard deviation (±14%) increase in %Vo₂ was associated with a 32% decrease in mortality in adjusted models (HR 0.68, 95% CI 0.53 to 0.87, p = 0.002). A %Vo₂ below 29%, 64% and 88% predicted less than 80% survival at 5, 10, and 15 years, respectively.

CONCLUSIONS

Post-transplant peak Vo₂ is a highly significant prognostic marker for long-term post-transplant survival. It remains to be seen whether decreased peak Vo₂ post-transplant is modifiable as a target to improve post-transplant longevity.

EFFECTS OF HIGH-INTENSITY TRAINING ON BASKETBALL PLAYERS

ABSTRACT Introduction: Basketball represents much more than a high-intensity exercise. Like most ball games, it is a continuous movement system. Objective: Study the effect of high-intensity interval training (HIT) on the aerobic metabolism of young basketball players. Methods: The author randomly divided male basketball players into an upper limb HIT group, lower limb HIT group, and control group by experimental method and statistical analysis, the control group received routine training, and aerobic exercise capacity was measured by increasing load test before and after the experiment. Results: During the lower extremity experiment, the mean power (MP) and peak power (PP) of the 4th full-force pedal stroke in the lower extremity HIT group increased (P<0.05), and the T/C ratio of the lower extremity HIT group was also implemented (P<0.05). There was no significant change in the indices of the control group (P>0.05). Conclusion: Upper extremity HIT in young male basketball players improved only upper extremity aerobic exercise capacity. In contrast, lower-extremity HIT improved both upper-extremity aerobic exercise capacity and lower-extremity anaerobic exercise capacity. Level of evidence II; Therapeutic studies - investigating treatment outcomes.

Extraordinary claims in the literature on high-intensity interval training (HIIT): IV. Is HIIT associated with higher long-term exercise adherence?

Nonadherence to and dropout from regular exercise and physical activity are important reasons why the field of exercise science has yet to fulfill its promise of improving public health on a global scale. Researchers have claimed that High-Intensity Interval Training (HIIT) is a feasible and sustainable exercise modality that may result in higher long-term adherence than moderate-intensity continuous exercise. If true, this would be a breakthrough discovery that could unlock the potential of exercise as a health-promoting intervention. We performed a systematic search of the literature and identified eight trials comparing HIIT to moderate-intensity continuous exercise, all of which involved follow-up periods of at least 12 months (i.e., SWIFT, Small Steps for Big Changes, SAINTEX-CAD, SMARTEX-HF, Generation 100, FITR, OptimEx-Clin, HITTS). Findings from these trials demonstrate that, while unsupervised, individuals initially assigned to HIIT tend to exercise at lower-than-prescribed intensities and HIIT groups demonstrate no advantage in long-term adherence.

The impact of high-intensity interval training on vascular function in adults: A systematic review and meta-analysis

Aim

We performed a systematic review and meta-analysis to investigate the effects of high-intensity interval training (HIIT) compared with moderate-intensity continuous training (MICT) or with no exercise (CON) on vascular function in adults who were free of cardiometabolic diseases and those with cardiometabolic diseases.

Methods

A search across three electronic databases including Scopus, PubMed, and Web of Science was conducted through February 2022 to identify the randomized trials evaluating HIIT vs. MICT and/or CON on vascular function as measured using brachial artery flow-mediated dilation (FMD) in adults. Separate analyses were conducted for HIIT vs. MICT and/or CON to calculate weighted mean differences (WMD) and 95% confidence intervals (95% CIs) using random or fixed models.

Results

A total of 36 studies involving 1,437 participants who were either free of cardiometabolic diseases or had cardiometabolic diseases were included in the meta-analysis. HIIT effectively increased FMD when compared with MICT [1.59% (95% CI 0.87-2.31), p = 0.001] or CON [3.80% (95% CI 2.58-5.01), p = 0.001]. Subgroup analysis showed that HIIT increased FMD in participants with cardiovascular and metabolic diseases, but not in participants who were free of cardiometabolic diseases. In addition, HIIT effectively increased FMD regardless of age and body mass index.

Conclusion

We confirm that HIIT is effective for improving vascular function in individuals with metabolic disorders and cardiovascular diseases and has a superior effect compared to MICT, demonstrating time efficiency.

Systematic review registration

[https://www.crd.york.ac.uk/prospero], identifier [CRD42022320863].

Patient-reported outcomes evaluation and assessment of facilitators and barriers to physical activity in the Transplantoux aerobic exercise intervention

Background

Transplantoux’s MVT exercise intervention prepares organ transplant recipients to cycle or hike up France’s Mont Ventoux. We aimed to assess (i) MVT’s effects on patient-reported outcomes (PROs) and (ii) perceived barriers and facilitators to physical activity.

Methods

Using a hybrid design, a convenience sample of transplant recipients participating in MVT (n = 47 cycling (TxCYC); n = 18 hiking (TxHIK)), matched control transplant recipients (TxCON, n = 213), and healthy MVT participants (HCON, n = 91) completed surveys to assess physical activity (IPAQ), health-related quality of life (HRQOL; SF-36 and EuroQol VAS), mental health (GHQ-12), and depressive symptomatology, anxiety, and stress (DASS-21) at baseline, then after 3, 6 (Mont Ventoux climb), 9, and 12 months. TxCYC and TxHIK participated in a 6-month intervention of individualized home-based cycling/hiking exercise and a series of supervised group training sessions. Barriers and facilitators to physical activity (Barriers and Motivators Questionnaire) were measured at 12 months.

Results

Regarding PROs, except for reducing TxHIK stress levels, MVT induced no substantial intervention effects. For both TxCYC and TxHIK, between-group comparisons at baseline showed that physical activity, HRQOL, mental health, depressive symptomatology and stress were similar to those of HCON. In contrast, compared to TxCYC, TxHIK, and HCON, physical activity, HRQOL and mental health were lower in TxCON. TxCON also reported greater barriers, lower facilitators, and different priority rankings concerning physical activity barriers and facilitators.

Conclusion

Barely any of the PROs assessed in the present study responded to Transplantoux’s MVT exercise intervention. TxCON reported distinct and unfavorable profiles regarding PROs and barriers and facilitators to physical activity. These findings can assist tailored physical activity intervention development.

Trial registration

Clinical trial notation: The study was approved by the University Hospitals Leuven’s Institutional Review Board (B322201523602).

A Systematic Review and Meta-Analysis of the Effectiveness of High-Intensity Interval Training in People with Cardiovascular Disease at Improving Depression and Anxiety

Background

To assess the effects of high-intensity interval training (HIIT) on depression and anxiety symptom in people with cardiovascular diseases (CVDs) compared with usual care (UC) and traditional aerobic continuous training (CT).

Methods

Randomized controlled trials (RCTs) that investigated the effectiveness of HIIT on depression and/or anxiety outcomes before and after treatment in people with CVDs were included. A systematic search of database containing PubMed, Web of Science, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, SPORTSDiscus, and CINAHL (EBSCOhost) was performed up to December 2021. The analyses of study characteristics, heterogeneity, and forest plot in analyses analogous were conducted via the pooled standardized mean difference (SMD) in random- or fixed-effect models as the measure of effectiveness.

Results

Twelve independent studies (515 participants) were included. One study was rated as low quality, and four studies were evaluated as high quality. The other studies were rated as moderate quality. Visual interpretation of funnel plots and Egger test indicated no evidence of publication bias. There was a statistically significant reduction in the severity of depression (12 studies, SMD = -0.42 [Random], 95% CI, -0.69 to -0.16, p=0.002, I ² = 52%) rather than that of anxiety symptoms (8 studies, SMD = -0.14 [Fixed], 95% CI, -0.35 to 0.06, p=0.18, I ² = 0%) following HIIT compared with UC and CT control groups. Subgroup analysis revealed that high-intensity treadmill training significantly improved (p=0.01) the depression symptom instead of training with a cycle ergometer (p=0.07) and strength training (p=0.40).

Conclusions

High-intensity interval treadmill training can significantly improve symptoms of depression rather than anxiety in cardiovascular patients compared to usual care and conventional aerobic continuous training.

Effectiveness of High-Intensity Interval Training and Continuous Moderate-Intensity Training on Blood Pressure in Physically Inactive Pre-Hypertensive Young Adults

The likelihood of pre-hypertensive young adults developing hypertension has been steadily increasing in recent years. Despite the fact that aerobic exercise training (AET) has demonstrated positive results in lowering high blood pressure, the efficacy of different types of AET among pre-hypertensive young adults has not been well-established. The objective of this study was to evaluate the effectiveness of high-intensity interval training (HIIT) and continuous moderate-intensity training (CMT) on the blood pressure (BP) of physically inactive pre-hypertensive young adults. In total, 32 adults (age 20.0 ± 1.1 years and BMI 21.5 ± 1.8) were randomly assigned to three groups: HIIT, CMT and control (CON). The HIIT and CMT groups participated in 5 weeks of AET, while the CON group followed a DASH diet plan only. The HIIT protocol consisted of a 1:4 min work to rest ratio of participants, at an 80−85% heart rate reserve (HR-reserve) and a 40−60% HR-reserve, respectively, for 20 min; the CMT group exercised at 40−60% of their HR-reserve continuously for 20 min. In both the HIIT and CMT groups, systolic blood pressure (SBP) (3.8 ± 2.8 mmHg, p = 0.002 vs. 1.6 ± 1.5 mmHg, p = 0.011) was significantly reduced, while significant reductions in the diastolic blood pressure (DBP) (2.9 ± 2.2 mmHg, p = 0.002) and mean arterial pressure (MAP) (3.1 ± 1.6 mmHg, p < 0.0005) were noted only in the HIIT group. No significant differences in SBP (−0.4 ± 3.7 mmHg, p = 0.718), DBP (0.4 ± 3.4 mmHg, p = 0.714), or MAP (0.1 ± 2.5 mmHg, p = 0.892) were observed in the CON group. Both HIIT and CMT decreased BP in physically inactive pre-hypertensive young adults; however, HIIT yielded more beneficial results in terms of reducing the SPB, DBP and MAP.

Predictors of Hypertension Development 1 Y After Heart Transplantation

BACKGROUND

Hypertension after heart transplantation (HTx) is common. We investigated predictors of and mechanisms for hypertension development during the first year after HTx, with particular attention toward immunosuppressive agents, reinnervation processes, and donor/recipient sex.

METHODS

Heart transplant recipients (HTxRs) were consecutively enrolled 7 to 12 wk after surgery and followed prospectively for 12 mo. Ambulatory blood pressure recordings and autonomic cardiovascular control assessments were performed at baseline and follow-up. Possible predictors of posttransplant hypertension development were investigated in bivariate linear regression analyses followed by multiple regression modeling.

RESULTS

A total of 50 HTxRs were included; 47 attended the follow-up appointment at 12 mo. Mean systolic and diastolic blood pressure increased significantly during the observational period (systolic blood pressure from 133 to 139 mm Hg, P = 0.007; diastolic blood pressure from 81 to 84 mm Hg, P = 0.005). The blood pressure increment was almost exclusively confined to HTxRs with a female donor heart, doubling the cases of systolic hypertension (from 6 to 13/14; 46% to 93%, P = 0.031) and diastolic hypertension (from 7 to 14/14; 54% to 100%, P = 0.031) in this subgroup. Autonomic cardiovascular control assessments suggested tonically constricted resistance and capacitance vessels in recipients with female donor hearts. Immunosuppressive agents and reinnervation markers were not associated with hypertension development.

CONCLUSIONS

Blood pressures increase during the first year after HTx, with female donor sex as a strong predictor of recipient hypertension development. The underlying mechanism seems to be enhanced peripheral vasoconstriction caused by attenuated cardiovascular homeostasis capabilities. Further studies are needed to confirm the results.

High-Intensity Interval Training Among Heart Failure Patients and Heart Transplant Recipients: A Systematic Review

High-intensity interval training (HIIT), an exercise training modality of cardiac rehabilitation, has shown growing evidence of improving cardiovascular patients' prognosis and health outcomes. This study aimed to identify and summarize the effects of HIIT in heart failure (HF) patients, heart transplantation (HTx) recipients, and HF patients before and after HTx. This systematic review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. For the past five years, a systematic search was done using PubMed, PubMed Central, Cochrane, Google Scholar, and ScienceDirect databases on September 15, 2021. Studies were selected based on the following predefined eligibility criteria: English-language randomized controlled trials (RCTs), observational studies, systematic reviews, and meta-analyses, which included HF patients and HTx patients, and assessment of effects HIIT. The relevant data were extracted to a predefined template. Consequently, quality assessment was done using each study's most commonly used assessment tools. The initial search generated 551 studies. Nine studies were included in the final selection - four RCTs, one cohort, one quasi-experimental study, two systematic reviews with meta-analyses, and one narrative review. HIIT was found to be generally superior or similar with other exercise training on VO2 peak, heart rate, LVEF, cardiac biomarkers, vascular function, blood pressure, body composition, and adverse events in HF patients and the aforementioned with QoL among HTx recipients. Data on cardiac remodeling and QoL of HF patients were inconclusive.

Impact of Exercise Modalities on Peripheral and Central Components of Cardiorespiratory Capacity in Heart Transplantation Patients: A Systematic Review and Meta-Analysis

Background and Objectives: To analyze the effects of aerobic, resistance, and combined training on peripheral and central components related to cardiorespiratory capacity after HTx. Materials and Methods: No time restriction was applied for study inclusion. MEDLINE/PubMed; EMBASE, CENTRAL, and PEDro databases were investigated. Studies reporting heart transplanted patients older than 19 years following aerobic, resistance, and combined training according. The outcomes included: V′O₂ peak, VE/V’CO₂ slope, heart rate (HR peak), systolic and diastolic blood pressure (SBP and DBP peak), maximum repetition test(1RM), sit-to-stand test, and flow-mediated dilation (FMD). The studies were selected by consensus. Four hundred ninety-two studies initially met the selection criteria. Cochrane handbook was used for abstracting data and assessing data quality and validity. Independent extraction by two observers was applied. Results: Isolated aerobic training leads to a greater increase in V′O₂ peak than combined training compared to the control group (p < 0.001, I2 = 0%). However, no significant differences were found in the subgroup comparison (p = 0.19, I2 = 42.1%). HR peak increased similarly after aerobic and combined training. High-intensity interval training (HIIT) was better than moderate continuous intensity to increase the V′O₂ after long term in HTx. Still, there is scarce evidence of HIIT on muscle strength and FMD. No change on VE/V’CO₂ slope, FMD, and SBP, DBP peak. 1RM and the sit-to-stand test increased after resistance training (p < 0.001, I2 = 70%) and CT (p < 0.001, I2 = 0%) when compared to control. Conclusions: Aerobic and combined training effectively improve VO₂ peak and muscle strength, respectively. HIIT seems the better choice for cardiorespiratory capacity improvements. More studies are needed to examine the impact of training modalities on VE/V’CO₂ slope and FMD.

Prognostic value of comprehensive intracoronary physiology assessment early after heart transplantation

AIMS

We evaluated the long-term prognostic value of invasively assessing coronary physiology after heart transplantation in a large multicentre registry.

METHODS AND RESULTS

Comprehensive intracoronary physiology assessment measuring fractional flow reserve (FFR), the index of microcirculatory resistance (IMR), and coronary flow reserve (CFR) was performed in 254 patients at baseline (a median of 7.2 weeks) and in 240 patients at 1 year after transplantation (199 patients had both baseline and 1-year measurement). Patients were classified into those with normal physiology, reduced FFR (FFR ≤ 0.80), and microvascular dysfunction (either IMR ≥ 25 or CFR ≤ 2.0 with FFR > 0.80). The primary outcome was the composite of death or re-transplantation at 10 years. At baseline, 5.5% had reduced FFR; 36.6% had microvascular dysfunction. Baseline reduced FFR [adjusted hazard ratio (aHR) 2.33, 95% confidence interval (CI) 0.88-6.15; P = 0.088] and microvascular dysfunction (aHR 0.88, 95% CI 0.44-1.79; P = 0.73) were not predictors of death and re-transplantation at 10 years. At 1 year, 5.0% had reduced FFR; 23.8% had microvascular dysfunction. One-year reduced FFR (aHR 2.98, 95% CI 1.13-7.87; P = 0.028) and microvascular dysfunction (aHR 2.33, 95% CI 1.19-4.59; P = 0.015) were associated with significantly increased risk of death or re-transplantation at 10 years. Invasive measures of coronary physiology improved the prognostic performance of clinical variables (χ2 improvement: 7.41, P = 0.006). However, intravascular ultrasound-derived changes in maximal intimal thickness were not predictive of outcomes.

CONCLUSION

Abnormal coronary physiology 1 year after heart transplantation was common and was a significant predictor of death or re-transplantation at 10 years.

Cardiac rehabilitation for heart transplant patients: Considerations for exercise training

Heart transplantation (HT) is the treatment of choice for eligible patients with end-stage chronic heart failure (HF). One-year survival world-wide is >85%. Many patients experience a reasonable functional ability post-HT, but episodes of acute rejection, as well as multiple co-morbidities such as hypertension, diabetes, chronic kidney disease and cardiac allograft vasculopathy are common. Immunosuppression with prednisone frequently results in increased body fat and skeletal muscle atrophy. Exercise capacity is below normal for most patients with a mean peak oxygen uptake (VO₂) of approximately 60% of expected. HT recipients have abnormal exercise physiology findings related to surgical cardiac denervation, diastolic dysfunction, and the legacy of reduced skeletal muscle oxidative capacity and impaired vasodilatory ability resulting from pre-HT chronic HF. The heart rate response to exercise is blunted. Cardiac reinnervation resulting in partial normalization of the heart rate response to exercise occurs in approximately 40% of HT recipients months to years after HT. Supervised exercise training in cardiac rehabilitation (CR) programs is safe and is recommended by professional societies both before (pre-habilitation) and after HT. Exercise training does not require alteration in immunosuppressants. Exercise training in adults after HT improves peak VO₂ and skeletal muscle strength. It has also been demonstrated to reduce the severity of cardiac allograft vasculopathy. In addition, CR exercise training is associated with reduced stroke risk, percutaneous coronary intervention, hospitalization for either acute rejection or HF, and death. There are only limited data for exercise training in the pediatric population.

Microcirculatory Resistance Predicts Allograft Rejection and Cardiac Events After Heart Transplantation

BACKGROUND

Single-center data suggest that the index of microcirculatory resistance (IMR) measured early after heart transplantation predicts subsequent acute rejection.

OBJECTIVES

The goal of this study was to validate whether IMR measured early after transplantation can predict subsequent acute rejection and long-term outcome in a large multicenter cohort.

METHODS

From 5 international cohorts, 237 patients who underwent IMR measurement early after transplantation were enrolled. The primary outcome was acute allograft rejection (AAR) within 1 year after transplantation. A key secondary outcome was major adverse cardiac events (MACE) (the composite of death, re-transplantation, myocardial infarction, stroke, graft dysfunction, and readmission) at 10 years.

RESULTS

IMR was measured at a median of 7 weeks (interquartile range: 3-10 weeks) post-transplantation. At 1 year, the incidence of AAR was 14.4%. IMR was associated proportionally with the risk of AAR (per increase of 1-U IMR; adjusted hazard ratio [aHR]: 1.04; 95% confidence interval [CI]: 1.02-1.06; p < 0.001). The incidence of AAR in patients with an IMR ≥18 was 23.8%, whereas the incidence of AAR in those with an IMR <18 was 6.3% (aHR: 3.93; 95% CI: 1.77-8.73; P = 0.001). At 10 years, MACE occurred in 86 (36.3%) patients. IMR was significantly associated with the risk of MACE (per increase of 1-U IMR; aHR: 1.02; 95% CI: 1.01-1.04; P = 0.005).

CONCLUSIONS

IMR measured early after heart transplantation is associated with subsequent AAR at 1 year and clinical events at 10 years. Early IMR measurement after transplantation identifies patients at higher risk and may guide personalized posttransplantation management.

Strong evidence for parasympathetic sinoatrial reinnervation after heart transplantation

BACKGROUND

Heart transplantation (HTx) surgically denervates the heart. We examined indices of sinoatrial reinnervation, with emphasis on (1) the occurrence and timing of parasympathetic reinnervation, and (2) the consequences of reinnervation for heart rate (HR) responsiveness and arterial baroreceptor sensitivity.

METHODS

Fifty HTx recipients were prospectively followed for 36 months after surgery. Hemodynamic variables and heart rate variability were continuously recorded at supine rest, 60 degrees head-up-tilt, during the Valsalva maneuver and during handgrip isometric exercise.

RESULTS

Suggesting parasympathetic reinnervation: at baseline rest, root of the mean squared differences of successive RR intervals increased from median 3.9(5.9) to 7.1(5.1) ms (p < 0.001); high-frequency power increased from 4.0(12) to 5.7(18.9) ms² (p = 0.018); and baroreceptor sensitivity increased from 0.04(0.36) to 1.3(2.4) ms/mmHg (p < 0.001). Suggesting sympathetic reinnervation: at baseline rest low-frequency power increased from 0.49(2.5) to 7.5(18.1) ms² (p < 0.001); and HR responses to sympathetic stimulation during (1) head-up tilt increased from 1.9(4.2) to 9.1(8.2) bpm (p < 0.001), (2) Valsalva increased from 1.6(1.4) to 8.3(10.8) bpm (p < 0.001) and (3) handgrip increased from 0.3(0.6) to 1.9(5.1) bpm (p < 0.001). Signs of sympathetic reinnervation emerged within 6 months, while signs of parasympathetic reinnervation emerged by 24 months.

CONCLUSIONS

Root of the mean squared differences of successive RR intervals, high-frequency and low-frequency variability, HR responsiveness and arterial baroreflex sensitivity all increased after HTx, suggesting functional parasympathetic and sympathetic sinoatrial reinnervation. Accordingly, the pathological regulatory state present in heart transplant recipients, which is responsible for a host of functional and clinical abnormalities, is being partially offset over time by restored autonomic control of the heart in many heart transplant recipients.

A randomized clinical study using optical coherence tomography to evaluate the short-term effects of high-intensity interval training on cardiac allograft vasculopathy: a HITTS substudy

Cardiac allograft vasculopathy (CAV) remains a leading cause of long-term mortality after heart transplantation. Both preventive measures and treatment options are limited. This study aimed to evaluate the short-term effects of high-intensity interval training (HIT) on CAV in de novo heart transplant (HTx) recipients as assessed by optical coherence tomography (OCT). The study population was a subgroup of the 81-patient HITTS study in which HTx recipients were randomized to HIT or moderate intensity continuous training (MICT) for nine consecutive months. OCT images from baseline and 12 months were compared to assess CAV progression. The primary endpoint was defined as the change in the mean intima area. Paired OCT data were available for 56 patients (n = 23 in the HIT group and n = 33 in the MICT group). The intima area in the entire study population increased by 25% [from 1.8±1.4mm² to 2.3±2.0mm² , p<0.05]. The change was twofold higher in the MICT group (0.6±1.2 mm² ) than in the HIT group (0.3±0.6 mm² ). However, the treatment effect of HIT was not significant (treatment effect = -0.3 mm² , 95% CI [-0.825 to 0.2 mm² ] p = 0.29). These results suggest that early initiation of HIT compared with MICT does not attenuate CAV progression in de novo HTx recipients. This article is protected by copyright. All rights reserved.

Physical Inactivity: A Modifiable Risk Factor for Morbidity and Mortality in Kidney Transplantation

In patients with chronic kidney disease, sedentary behavior is widely recognized as a significant risk factor for cardiovascular disease, diabetes, obesity, osteoporosis, cancer, and depression. Nevertheless, the real impact of physical inactivity on the health of kidney transplant (KT) recipients remains uncertain. Over the last decade, there has been a renewed interest in exploring the effects of regular physical exercise on transplant-related outcomes. There is now mounting evidence that physical activity may reduce the burden of cardiovascular risk factors, preserve allograft function, minimize immunosuppression requirement, and ameliorate the quality of life of KT recipients. Many positive feedbacks can be detected in the early stages of the interventions and with a minimal exercise load. Despite these encouraging results, the perceived role of physical activity in the management of KT candidates and recipients is often underrated. The majority of trials on exercise training are small, relatively short, and focused on surrogate outcomes. While waiting for larger studies with longer follow-up, these statistical limitations should not discourage patients and doctors from initiating exercise and progressively increasing intensity and duration. This narrative review summarizes current knowledge about the deleterious effects of physical inactivity after KT. The benefits of regular physical exercise are also outlined.

Can high-intensity interval training improve mental health outcomes in the general population and those with physical illnesses? A systematic review and meta-analysis

OBJECTIVE

High-intensity interval training (HIIT) is a safe and feasible form of exercise. The aim of this meta-analysis was to investigate the mental health effects of HIIT, in healthy populations and those with physical illnesses, and to compare the mental health effects to non-active controls and other forms of exercise.

DESIGN

Random effects meta-analyses were undertaken for randomised controlled trials (RCTs) comparing HIIT with non-active and/or active (exercise) control conditions for the following coprimary outcomes: mental well-being, symptoms of depression, anxiety and psychological stress. Positive and negative affect, distress and sleep outcomes were summarised narratively.

DATA SOURCES

Medline, PsycINFO, Embase and CENTRAL databases were searched from inception to 7 July 2020.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

RCTs that investigated HIIT in healthy populations and/or those with physical illnesses and reported change in mental well-being, depression, anxiety, psychological stress, positive/negative affect, distress and/or sleep quality.

RESULTS

Fifty-eight RCTs were retrieved. HIIT led to moderate improvements in mental well-being (standardised mean difference (SMD): 0.418; 95% CI: 0.135 to 0.701; n=12 studies), depression severity (SMD: -0.496; 95% CI: -0.973 to -0.020; n=10) and perceived stress (SMD: -0.474; 95% CI: -0.796 to -0.152; n=4) compared with non-active controls, and small improvements in mental well-being compared with active controls (SMD:0.229; 95% CI: 0.054 to 0.403; n=12). There was a suggestion that HIIT may improve sleep and psychological distress compared with non-active controls: however, these findings were based on a small number of RCTs.

CONCLUSION

These findings support the use of HIIT for mental health in the general population.

LEVEL OF EVIDENCE

The quality of evidence was moderate-to-high according to the Grading of Recommendations Assessment, Development and Evaluation) criteria.

PROSPERO REGISTRATION NUMBER

CRD42020182643.

Early Signs of Sinoatrial Reinnervation in the Transplanted Heart

BACKGROUND

Heart transplantation (HTx) surgically transects all connections to the heart, including the autonomic nerves. We prospectively examined signs, timing and consequences of early sympathetic and parasympathetic sinoatrial reinnervation, as well as explored indirect evidence of afferent cardiopulmonary reinnervation.

METHODS

Fifty HTx recipients were assessed at 2.5, 6, and 12 mo after HTx. For comparison, 50 healthy controls were examined once. Continuous, noninvasive recordings of hemodynamic variables and heart rate variability indices were performed at supine rest, 0.2 Hz controlled breathing, 60° head-up-tilt, during the Valsalva maneuver and during handgrip isometric exercise.

RESULTS

In HTx recipients, supine low-frequency heart rate variability gradually increased; supine high-frequency variability did not change; heart rate variability indices during controlled breathing remained unaltered; heart rate responses during tilt and isometric exercise gradually increased; the tachycardia response during Valsalva maneuver increased, while the bradycardia response remained unchanged; and indices of baroreflex sensitivity improved. Responses remained low compared to healthy controls. A negative correlation between indices of preload and heart rate response during head-up tilt emerged at 12 mo.

CONCLUSIONS

Results suggest that sympathetic reinnervation of the sinoatrial node starts within 6 mo after HTx and strengthens during the first year. No evidence of early parasympathetic reinnervation was found. Indirect signs of afferent reinnervation of cardiopulmonary low-pressure baroreceptors emerged at 12 mo. Better sympathetic sinoatrial control improved heart rate responsiveness to orthostatic challenge and isometric exercise, as well as heart rate buffering of blood pressure fluctuations.

Effect of exercise on endothelial function in heart transplant recipients: systematic review and meta-analysis

Endothelial dysfunction is associated with increased cardiovascular risk and death in heart transplant recipients (HTx). Although the measurement of peripheral endothelial function is considered a significant predictor of cardiovascular events in several populations, few studies have investigated this outcome after therapeutic strategies, including different exercise types, duration, and intensity. This systematic review and meta-analysis aimed to investigate the effects of continuous moderate exercise (CON) or high-intensity interval training (HIIT) to improve endothelial function (EF) in HTx. The search was conducted in Cochrane Central Registry of Controlled Trials (CENTRAL), MEDLINE (via PubMed), Web of Science and Scopus/Elsevier, CINAHL/Ebsco, Physiotherapy Evidence Database (PEDro), LILACS/BIREME, and SciELO databases. Quality of the evidence was assessed using the Grading of Recommendations Assessment Development and Evaluation (GRADE). The search strategy retrieved 5192 titles. A total of four articles met the inclusion criteria and were included for the qualitative analysis. Meta-analysis showed that exercises improved EF ([mean difference-MD] 3.48 95% CI - 0.29 to 7.25, p = 0.007) when compared with the control. However, there was a poor quality of evidence to demonstrate that CON or HIIT is better than usual care to improve EF. Exercise training provides benefits to patients, but the poor quality of evidence does not allow us to state that exercise is related to endothelial function improvement in HTx.

Cardiac rehabilitation and its essential role in the secondary prevention of cardiovascular diseases

Cardiovascular diseases are the most common causes of mortality worldwide. They are frequently the reasons for patient hospitalization, their incapability for work, and disability. These diseases represent a significant socio-economic burden affecting the medical system as well as patients and their families. It has been demonstrated that the etiopathogenesis of cardiovascular diseases is significantly affected by lifestyle, and so modification of the latter is an essential component of both primary and secondary prevention. Cardiac rehabilitation (CR) represents an efficient secondary prevention model that is especially based on the positive effect of regular physical activity. This review presents an overview of basic information on CR with a focus on current trends, such as the issue of the various training modalities, utilization, and barriers to it or the use of telemedicine technologies. Appropriate attention should be devoted to these domains, as CR continues evolving as an effective and readily available intervention in the future.

Cardiac Rehabilitation for Patients With Heart Failure: JACC Expert Panel

Cardiac rehabilitation is defined as a multidisciplinary program that includes exercise training, cardiac risk factor modification, psychosocial assessment, and outcomes assessment. Exercise training and other components of cardiac rehabilitation (CR) are safe and beneficial and result in significant improvements in quality of life, functional capacity, exercise performance, and heart failure (HF)-related hospitalizations in patients with HF. Despite outcome benefits, cost-effectiveness, and strong practice guideline recommendations, CR remains underused. Clinicians, health care leaders, and payers should prioritize incorporating CR as part of the standard of care for patients with HF.

Contemporary review of exercise in heart transplant recipients

Heart transplantation (HTx) is a therapeutic option for a selected group of patients with end-stage heart failure. Although secondary prevention including exercise therapy is recommended in the management of patients following HTx, little information is available on their metabolic and physiological consequences in HTx. Therefore, we aimed to conduct a contemporary review the effectiveness of exercise therapy on functional capacity, cardiovascular health and health-related quality of life for adult HTx patients. We searched the database MEDLINE for articles published between January 2015 and October 2020 and were able to include 6 studies involving 202 patients. Larger improvements in exercise capacity were seen after high-intensity interval training and in patients with evidence of cardiac reinnervation. Clinically relevant reductions were observed for daytime and 24 h ambulatory blood pressure after exercise training and following a single bout of aerobic exercise. Finally, limited data suggest that quality of life is higher in HTx patients following high-intensity training. In summary, the available evidence shows the potential for exercise as a vital treatment in patients following HTx. Yet, the scant data calls for more well-designed and adequately powered studies to support its effectiveness and to unravel optimal exercise characteristics, which would allow for more effective and person-tailored exercise prescription.

Effect of High-Intensity Interval Training on Aerobic Capacity and Heart Rate Control of Heart Transplant Recipients: a Systematic Review with Meta-Analysis

INTRODUCTION

Heart transplantation (HTx) is the gold standard procedure for selected individuals with refractory heart failure. Highintensity interval training (HIIT) is safe and allows patients to exercise in high intensity for longer time when compared to moderateintensity continuous training (MICT). The primary aim of this study was to perform a systematic review and meta-analysis about the effect of HIIT compared to MICT on exercise capacity, peak heart rate, and heart rate reserve in HTx recipients. Secondarily, we pooled data comparing MICT and no exercise training in these patients.

METHODS

This systematic review followed the standardization of the Preferred Reporting Items for Systematic Reviews and Metaanalyses statement and the Cochrane Collaboration Handbook. We presented the treatment effects of HIIT on the outcomes of interest as mean difference (MD) and 95% confidence interval (CI). Metaanalysis was performed using the random-effects, generic inverse variance method.

RESULTS

HIIT improved peak oxygen consumption (peakVO2) (MD = 2.1; 95% CI 1.1, 3.1; P<0.0001), peak heart rate (MD = 3.4; 95% CI 0.8, 5.9; P=0.009), and heart rate reserve (MD = 4.8; 95% CI -0.05, 9.6; P=0.05) compared to MICT. Improvements on peakVO₂ (MD = 3.5; 95% CI 2.3, 4.7; P<0.00001) and peak heart rate (MD = 5.6; 95% CI 1.6, 9.6; P=0.006) were found comparing HIIT and no exercise training.

CONCLUSION

Current available evidence suggests that HIIT leads to improvements on peakVO₂, peak heart rate, and heart rate reserve compared to MICT in HTx recipients. However, the superiority of HIIT should be tested in isocaloric protocols.

Functional evidence of low-pressure cardiopulmonary baroreceptor reinnervation 1 year after heart transplantation

PURPOSE

Heart transplantation (HTx) implies denervation of afferent neural connections. Reinnervation of low-pressure cardiopulmonary baroreceptors might impact the development and treatment of hypertension, but little is known of its occurrence. The present prospective study investigated possible afferent reinnervation of low-pressure cardiopulmonary baroreceptors during the first year after heart transplantation.

METHODS

A total of 50 heart transplant recipients (HTxRs) were included and were evaluated 7-12 weeks after transplant surgery, with follow-up 6 and 12 months later. In addition, a reference group of 50 healthy control subjects was examined once. Continuous, non-invasive recordings of cardiovascular variables were carried out at supine rest, during 15 min of 20° head-up tilt, during Valsalva maneuver and during 1 min of 30% maximal voluntary handgrip. In addition, routine clinical data including invasive measurements were used in the analyses.

RESULTS

During the first year after HTx, the heart rate (HR) response to 20° head-up tilt partly normalized, a negative relationship between resting mean right atrial pressure and HR tilt response developed, low-frequency variability of the RR interval and systolic blood pressure at supine rest increased, and the total peripheral resistance response to Valsalva maneuver became stronger.

CONCLUSION

Functional assessments suggest that afferent reinnervation of low-pressure cardiopulmonary receptors occurs during the first year after heart transplantation, partially restoring reflex-mediated responses to altered cardiac filling.

Cardiac Rehabilitation in Heart Failure

Heart failure (HF) is a complex clinical syndrome caused by a structural and/or functional cardiac abnormality, resulting in reduced organ perfusion. The goals of treatment in patients with HF are to improve functional capacity and quality of life, and to reduce mortality. Cardiac rehabilitation (CR) including exercise training is one of the treatment options, and current guidelines recommend CR as safe and effective for patients with HF. CR has been known to improve exercise capacity and quality of life, minimize HF progression, and lower mortality in patients with HF. Improvement of vascular endothelial function, activation of the neurohormonal system, increase of mitochondrial oxygen utilization in peripheral muscles, and increase of chronotropic responses are possible mechanisms of the beneficial effects of exercise-based CR in HF. Although CR has been shown to decrease morbidity and mortality, it is underutilized in clinical practice. Despite the existence of concrete evidence of clinical benefits, the CR participation rates of patients with HF range from only 14% to 43% worldwide, with high dropout rates after enrollment. These low participation rates have been attributed to several barriers, including patient factors, professional factors, and service factors. The motivation for participating in CR and for overcoming the patients' barriers for CR before discharge should be provided to each patient. Current guidelines strongly recommend applying a CR program to all eligible patients with HF.

Exercise training modalities for heart transplant recipients: a systematic review and network meta-analysis protocol

INTRODUCTION

Heart transplantation is the gold standard treatment for selected patients with end-stage heart failure. Although this procedure can improve quality and prolong life expectancy, several of these patients persist with decreased exercise tolerance. Evidence suggests that exercise training can bring multifactorial benefits to heart transplant (HTx) recipients. However, it is unclear that exercise modality should be preferred. Therefore, the aim of this systematic review and network meta-analysis is to compare the efficacy and safety of different training modalities in HTx recipients.

METHODS AND ANALYSIS

We will perform a comprehensive literature search in PubMed/MEDLINE, Embase, The Cochrane Library, CINAHL, Scopus, SportDISCUS, Web of Science Core Collection and PEDro from inception until November 2020. Two registries (ClinicalTrials.gov and REBEC) will also be searched for potential results in unpublished studies. There will be no restriction on language, date of publication, publication status or sample size. We will include randomised controlled trials enrolling adult HTx recipients with the presence of at least one exercise training group, which might be compared with another training modality and/or a non-exercise control group for a minimum of 4 weeks of intervention. The primary outcomes will be peak oxygen consumption and occurrence of adverse events. As secondary outcomes, the interaction between pulmonary ventilation, pulmonary perfusion and cardiac output, oxygen uptake efficiency slope, heart rate response, oxygen pulse, peak blood pressure and peak subjective perception of effort. In addition, we will evaluate the 6 min walking distance, health-related quality of life, endothelial function, muscle strength, body fat percentage and lean mass. Risk of bias will be assessed using the Cochrane RoB V.2.0 tool, and we plan to use the Confidence in Network Meta-Analysis tool to assess confidence in the results. All materials (raw data, processed data, statistical code and outputs) will be shared in a public repository.

ETHICS AND DISSEMINATION

Given the nature of this study, no ethical approval will be required. We believe that the findings of this study may show which is the most efficacious and safe physical training modality for HTx recipients. The completed systematic review and network meta-analysis will be submitted to a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42020191192.

Long-term effects of high-intensity training vs moderate intensity training in heart transplant recipients: A 3-year follow-up study of the randomized-controlled HITTS study

The randomized controlled High-Intensity Interval Training in De Novo Heart Transplant Recipients in Scandinavia (HITTS) study compared 9 months of high-intensity interval training (HIT) with moderate intensity continuous training in de novo heart transplant recipients. In our 3-year follow-up study, we aimed to determine whether the effect of early initiation of HIT on peak oxygen consumption (VO_2peak ) persisted for 2 years postintervention. The study's primary end point was the change in VO_2peak (mL/kg/min). The secondary end points were muscle strength, body composition, heart rate response, health-related quality of life, daily physical activity, biomarkers, and heart function. Of 78 patients who completed the 1-year HITTS trial, 65 entered our study and 62 completed the study tests. VO_2peak increased from baseline to 1 year and leveled off thereafter. During the intervention period, the increase in VO_2peak was larger in the HIT arm; however, 2 years later, there was no significant between-group difference in VO_2peak . However, the mean change in the anaerobic threshold and extensor muscle endurance remained significantly higher in the HIT group. Early initiation of HIT after heart transplantation appears to have some sustainable long-term effects. Clinical trial registration number: NCT01796379.

Exercise-based rehabilitation strategies in heart transplant recipients: Focus on high-intensity interval training

Despite progressive improvement in medical therapy and standard care, the exercise capacity of heart transplant recipients is reduced compared with age-matched healthy individuals. Exercise-based rehabilitation programs have been shown to improve the exercise capacity of transplant patients through a multifactorial effect. In this context, high-intensity interval exercise is a growing field of research, with current evidence suggesting a major benefit in heart transplant recipients compared with a conventional training protocol. Therefore, this study aimed to provide an overview of the mechanisms involved in the reduced exercise capacity of heart transplant patients and a review of current rehabilitation strategies with a special focus on the mechanisms and clinical effects of high-intensity interval training exercise.

Changes in Resting and Exercise Hemodynamics Early After Heart Transplantation: A Simulation Perspective

Introduction: During heart transplantation (HTx), cardiac denervation is inevitable, thus typically resulting in chronic resting tachycardia and chronotropic incompetence with possible consequences in patient quality of life and clinical outcomes. To this date, knowledge of hemodynamic changes early after HTx is still incomplete. This study aims at providing a model-based description of the complex hemodynamic changes at rest and during exercise in HTx recipients (HTxRs). Materials and Methods: A numerical model of early HTxRs is developed that integrates intrinsic and autonomic heart rate (HR) control into a lumped-parameter cardiovascular system model. Intrinsic HR control is realized by a single-cell sinoatrial (SA) node model. Autonomic HR control is governed by aortic baroreflex and pulmonary stretch reflex and modulates SA node activity through neurotransmitter release. The model is tuned based on published clinical data of 15 studies. Simulations of rest and exercise are performed to study hemodynamic changes associated with HTxRs. Results: Simulations of HTxRs at rest predict a substantially increased HR [93.8 vs. 69.5 beats/min (bpm)] due to vagal denervation while maintaining normal cardiac output (CO) (5.2 vs. 5.6 L/min) through a reduction in stroke volume (SV) (55.4 vs. 82 mL). Simulations of exercise predict markedly reduced peak CO (13 vs. 19.8 L/min) primarily resulting from diminished peak HRs (133.9 vs. 169 bpm) and reduced ventricular contractility. Yet, the model results show that HTxRs can maintain normal CO for low- to medium-intensity exercise by increased SV augmentation through the Frank-Starling mechanism. Conclusion: Relevant hemodynamic changes occur after HTx. Simulations suggest that (1) increased resting HRs solely result from the absence of vagal tone; (2) chronotropic incompetence is the main limiting factor of exercise capacity whereby peripheral factors play a secondary role; and (3) despite the diminished exercise capacity, HTxRs can compensate chronotropic incompetence by a preload-mediated increase in SV augmentation and thus maintain normal CO in low- to medium-intensity exercise.

High-intensity interval training and health-related quality of life in de novo heart transplant recipients - results from a randomized controlled trial

Background

Studies on the effect of high-intensity interval training (HIT) compared with moderate intensity continuous training (MICT) on health-related quality of life (HRQoL) after heart transplantation (HTx) is scarce. No available studies among de novo HTx recipients exists. This study aimed to investigate the effect of HIT vs. MICT on HRQoL in de novo recipients.

Methods

The HITTS study randomized eighty-one de novo HTx recipients to receive either HIT or MICT (1:1). The HIT intervention were performed with 2–4 interval bouts with an intensity of 85–95% of maximal effort. The MICT group exercised at an intensity of 60–80% of their maximal effort with a duration of 25 min. HRQoL was assessed by the Short Form-36 version 2 (SF-36v2) and the Hospital Anxiety and Depression Scale, mean 11 weeks after surgery and after a nine months’ intervention. The participants recorded their subjective effect of the interventions on their general health and well-being on a numeric visual analogue scale. Clinical examinations and physical tests were performed. Differences between groups were investigated with independent Student t-tests and with Mann-Whitney U tests where appropriate. Within-group differences were analyzed with Paired-Sample t-tests and Wilcoxon Signed Rank tests. Correlations between SF-36 scores and VO_2peak were examined with Pearson’s correlations.

Results

Seventy-eight participants completed the intervention. Both exercise modes were associated with improved exercise capacity on the physical function scores of HRQoL. Mental health scores remained unchanged. No differences in the change in HRQoL between the groups occurred except for Role Emotional subscale with a larger increase in the HIT arm. Better self-reported physical function was associated with higher VO_2peak and muscle strength.

Conclusion

HIT and MICT resulted in similar mean changes in HRQoL the first year after HTx. Both groups experienced significant improvements in the physical SF-36v2.

Trial registration

ClinicalTrials.gov number: NCT01796379 Registered 18 February 2013.

Exercise after Heart Transplantation: Typical Alterations, Diagnostics and Interventions

For the treatment of terminal heart failure, heart transplantation is considered to be the gold standard, leading to significantly improved quality of life and long-time survival. For heart transplant recipients, the development and maintenance of good functional performance and adequate exercise capacity is crucial for renewed participation and integration in self-determined live. In this respect, typical transplant-related alterations must be noted that play a significant role, leading to restrictions both centrally and peripherally. Before patients begin intensive and structured exercise training, a comprehensive diagnosis of their exercise capacity should take place in order to stratify the risks involved and to plan the training units accordingly. Particularly endurance sports and resistance exercises are recommended to counter the effects of the underlying disease and the immunosuppressive medication. The performance level achieved can vary considerably depending on their individual condition, from gentle activity through a non-competitive-level to intensive competitive sports. This paper includes an overview of the current literature on heart transplant recipients, their specific characteristics, as well as typical cardiovascular and musculoskeletal alterations. It also discusses suitable tools for measuring exercise capacity, recommendations for exercise training, required precautions and the performance level usually achieved.

Effect of high-intensity interval training in young heart transplant recipients: results from two randomized controlled trials

Background

Little is known about the effect of exercise in young heart transplant recipients, and results on group level is lacking. This study summarizes the findings of the youngest participants in two previous randomized controlled trials.

Method

This is a hypothesis-generating study reporting the main results from the youngest participants in two larger randomized controlled trials investigating the effect of high-intensity interval training (HIT). The article summarizes the main results from 28 young participants (< 40 year of age) who have participated in two previous studies which evaluated the effect of HIT vs. controls in adult heart transplant recipients. One of the studies included de novo heart transplant recipients and the other included maintenance heart transplant recipients.All study tests were performed in-hospital, in the specialist health care setting, but the exercise intervention was carried out locally, in cooperation with the primary health care. In both studies the exercise intervention lasted for 9-12 months. In one study, HIT (85-95% of peak effort) was compared to controls (no specific intervention), and in the other study HIT was compared to moderate, continuous exercise (MICT, 60-80% of peak effort). The main outcome measure was peak oxygen uptake (VO_2peak) and a secondary endpoint was muscle strength.

Results

The summarized findings from the youngest heart transplant recipients in these two studies demonstrated mainly that the improvement in peak oxygen uptake among the younger recipients (< 40 years) was much larger (4.7 vs. 1.2 ml/kg/min and 7.0 vs. 2.2 ml/kg/min) compared to the improvement among the older recipients (≥ 40 years), and in accordance with results from adult heart transplant populations: HIT, compared to MICT, induced the largest improvement in peak oxygen consumption, also in the younger heart transplant recipients.

Conclusions

These results suggest that young heart transplant recipients have a greater effect of HIT than of MICT and may also suggest that younger recipients benefit more from high-intensity interval training than their older co-patients. However, larger randomized studies focusing on the young heart transplant population is strongly needed to confirm this hypothesis.

Trial registration

Clinical trial registrations: NCT01796379 and NCT01091194.