Exercise after heart transplantation: An overview

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.

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.

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.

Relationships among norepinephrine levels, exercise capacity, and chronotropic responses in heart failure patients

In heart failure (HF) patients, the pathophysiological mechanisms of severe exercise intolerance and impaired exercise capacity are related to both central and peripheral abnormalities. The central abnormalities in HF patients include impaired cardiac function and chronotropic incompetence (CI). Indeed, CI, the inability to adequately increase heart rate (HR) from rest to exercise often exhibited by HF patients, is related to activation of the sympathetic nervous system (SNS) yielding a rise in circulating norepinephrine (NE). CI may result from downregulation of β-adrenergic receptors, β-blocker usage, high baseline HR, or due to a combination of factors. This paper discusses the role of elevated NE in altering chronotropic responses in HF patients and consequently resulting in impaired exercise capacity. We suggest that future research should focus on the potential treatment of CI with rate-adaptive pacing, using a sensor to measure physical activity, without inducing deleterious hormonal activation of the sympathetic system.

Effects of Exercise on Circulating Extracellular Vesicles in Cardiovascular Disease

The evidence that physical exercise has multiple beneficial effects and is essential to a healthy lifestyle is widely accepted for a long-time. The functional and psychological changes promoted by exercise improve clinical outcomes and prognosis in several diseases, by decreasing mortality, disease severity, and hospital admissions. Nonetheless, the mechanisms that regulate the release, uptake, and communication of several factors in response to exercise are still not well defined. In the last years, extracellular vesicles have attracted significant interest in the scientific community due to their ability to carry and deliver proteins, lipids, and miRNA to distant organs in the body, promoting a very exciting crosstalk machinery. Moreover, increasing evidence suggests that exercise can modulate the release of those factors within EVs into the circulation, mediating its systemic adaptations.In this chapter, we summarize the effects of acute and chronic exercise on the extracellular vesicle dynamics in healthy subjects and patients with cardiovascular disease. The understanding of the changes in the cargo and kinetics of extracellular vesicles in response to exercise may open new possibilities of research and encourage the development of novel therapies that mimic the effects of exercise.

Iron homeostasis in heart transplant recipients randomized to ferric derisomaltose or placebo

Introduction

The randomized IronIC trial evaluated the effect of intravenous ferric derisomaltose on physical capacity in iron‐deficient, maintenance heart transplant (HTx) recipients. Iron deficiency was defined as in heart failure with high cut‐points for ferritin to compensate for inflammation. However, intravenous iron did not improve physical capacity except in patients with ferritin <30 μg/L. We aimed to explore determinants of iron status in the 102 IronIC participants to better define iron deficiency in the HTx population.

Methods

We assessed key governors of iron homeostasis, such as hepcidin, soluble transferrin receptor (sTfR), and interleukin‐6 (IL‐6). We also measured growth factors and inflammatory markers with relevance for iron metabolism. The results were compared to those of 21 healthy controls.

Results

Hepcidin did not differ between HTx recipients and controls, even though markers of inflammation were modestly elevated. However, HTx recipients with ferritin <30 μg/L or sTfR above the reference range had significantly reduced hepcidin levels suggestive of true iron deficiency. In these patients, intravenous iron improved peak oxygen uptake. Hepcidin correlated positively with ferritin and negatively with sTfR.

Conclusion

HTx recipients with iron deficiency as defined in heart failure do not have elevated hepcidin levels, although inflammatory markers are modestly increased. The high ferritin cut‐offs used in heart failure may not be suitable to define iron deficiency in the HTx population. We suggest that hepcidin and sTfR should be measured to identify patients with true iron deficiency, who might benefit from treatment with intravenous iron.

Cardiovascular Responses to Commonly Used Tests in and Outside of the Laboratory Settings

Several tests are available for assessing cardiovascular response to various interventions which may be given in the laboratory, or outside of it in the field. The tests are meant to excite or deactivate cardiovascular and other sensory receptors which signal the central mechanisms. They have been found useful in generating data to study cardiovascular effects on subjects exposed to specialized physical training (e.g., athletes), in the evaluation of people engaged in special occupations such as pilots, astronauts, and other military personnel, and in training undergraduate and postgraduate students. If the response does not fit into the physiological norm, it may reflect a temporary aberration, or a more serious defect in the cardiovascular control mechanism because of disease. Interpretation of data generated may vary between various operators/observers. Here, an attempt has been made to bring out responses of the cardiovascular system to the commonly used tests, and their applicability in clinical situations.

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.

Long-term heart transplant recipients: heart rate-related effects on augmented transfer function coherence during repeated squat-stand maneuvers in males

Previous research has highlighted that squat-stand maneuvers (SSMs) augment coherence values within the cerebral pressure-flow relationship to ∼0.99. However, it is not fully elucidated if mean arterial pressure (MAP) leads to this physiological entrainment independently, or if heart rate (HR) and/or the partial pressure of carbon dioxide (Pco₂) also have contributing influences. A 2:1 control-to-case model was used in the present investigation [participant number (n) = 40; n = 16 age-matched (AM); n = 16 donor control (DM); n = 8 heart transplant recipients (HTRs)]. The latter group was used to mechanistically isolate the extent to which HR influences the cerebral pressure-flow relationship. Participants completed 5 min of squat-stand maneuvers at 0.05 Hz (10 s) and 0.10 Hz (5 s). Linear transfer function analysis (TFA) examined the relationship between different physiological inputs (i.e., MAP, HR, and Pco₂) and output [cerebral blood velocity (CBV)] during SSM; and cardiac baroreceptor sensitivity (BRS). Compared with DM, cardiac BRS was reduced in AM (P < 0.001), which was further reduced in HTR (P < 0.045). In addition, during the SSM, HR was elevated in HTR compared with both control groups (P < 0.001), but all groups had near-maximal coherence metrics ≥0.98 at 0.05 Hz and ≥0.99 at 0.10 Hz (P ≥ 0.399). In contrast, the mean HR-CBV/Pco₂-CBV relationships ranged from 0.38 (HTR) to 0.81 (DM). Despite near abolishment of BRS and blunted HR following heart transplantation, long-term HTR exhibited near-maximal coherence within the MAP-CBV relationship, comparable with AM and DM. Therefore, these results show that the augmented coherence with SSM is driven by blood pressure, whereas elevations in TFA coherence as a result of HR contribution are likely correlational in nature.

Exercise capacity, muscle strength and objectively measured physical activity in patients after heart transplantation

Maximal exercise capacity of patients after heart transplantation (HTX) remains limited, affecting their quality of life. Evidence on the evolution of muscle strength and physical activity (PA) post-HTX is lacking, but a prerequisite to tailor cardiac rehabilitation programmes. Forty-five consecutive patients were evaluated every 3 months during the first year post-HTX. Functional exercise capacity (Six minutes walking distance test (6MWD)), peripheral (Quadriceps strength (QF)) and respiratory (Maximal inspiratory strength (MIP)) muscle strength were evaluated. PA (number of steps (PAsteps), active time (PAactive) and sedentary time (PAsed)) was objectively measured. 6MWD, QF, MIP, PAsteps and PAactive significantly improved over time (P < 0.001). No change in PAsed was noticed (P = 0.129). Despite improvements in 6MWD and QF, results remained substantially below those of age-and gender-matched healthy subjects. One year post-HTX, 30% of patients presented with peripheral muscle weakness. Baseline levels of 6MWD and QF were significantly higher in patients with pretransplant LVAD-implantation and this difference was maintained during follow-up. cardiac rehabilitation, combining aerobic exercise training and peripheral muscle strength training, is mandatory in patients post-HTX. Inspiratory muscle training should be implemented when respiratory muscle weakness is present. Programmes improving physical activity and reducing sedentary time post-HTX are essential.

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.

Cardiac Rehabilitation in German Speaking Countries of Europe-Evidence-Based Guidelines from Germany, Austria and Switzerland LLKardReha-DACH-Part 2

Background: Scientific guidelines have been developed to update and harmonize exercise based cardiac rehabilitation (ebCR) in German speaking countries. Key recommendations for ebCR indications have recently been published in part 1 of this journal. The present part 2 updates the evidence with respect to contents and delivery of ebCR in clinical practice, focusing on exercise training (ET), psychological interventions (PI), patient education (PE). In addition, special patients’ groups and new developments, such as telemedical (Tele) or home-based ebCR, are discussed as well. Methods: Generation of evidence and search of literature have been described in part 1. Results: Well documented evidence confirms the prognostic significance of ET in patients with coronary artery disease. Positive clinical effects of ET are described in patients with congestive heart failure, heart valve surgery or intervention, adults with congenital heart disease, and peripheral arterial disease. Specific recommendations for risk stratification and adequate exercise prescription for continuous-, interval-, and strength training are given in detail. PI when added to ebCR did not show significant positive effects in general. There was a positive trend towards reduction in depressive symptoms for “distress management” and “lifestyle changes”. PE is able to increase patients’ knowledge and motivation, as well as behavior changes, regarding physical activity, dietary habits, and smoking cessation. The evidence for distinct ebCR programs in special patients’ groups is less clear. Studies on Tele-CR predominantly included low-risk patients. Hence, it is questionable, whether clinical results derived from studies in conventional ebCR may be transferred to Tele-CR. Conclusions: ET is the cornerstone of ebCR. Additional PI should be included, adjusted to the needs of the individual patient. PE is able to promote patients self-management, empowerment, and motivation. Diversity-sensitive structures should be established to interact with the needs of special patient groups and gender issues. Tele-CR should be further investigated as a valuable tool to implement ebCR more widely and effectively.

Prevalence of iron deficiency in heart transplant recipients

BACKGROUND

Optimal iron management is crucial to marginal patients such as heart transplant recipients. As inflammatory mechanisms are present in transplant recipients, the definition of iron deficiency used in the general population might not be appropriate.

OBJECTIVE

To evaluate the prevalence and determinants of iron deficiency in Norwegian heart transplant recipients.

METHODS

We consecutively assessed iron parameters in all Norwegian heart transplant recipients at their annual follow-up. Several definitions of iron deficiency suggested in the literature were assessed: ferritin <100 µg/L, or ferritin 100-300 µg/L combined with transferrin saturation of <20% (ID_HF ); ferritin <100 µg/L (ID_F100 ); transferrin saturation of <20% (ID_Tsat ), and ferritin <30 µg/L (ID_F30 ).

RESULTS

179 of 378 heart transplant recipients (47%) had iron deficiency defined as ID_HF . 152 patients (40%) had ID_F100 , and 103 patients (27%) had ID_Tsat . 17 patients (5%) had ID_F30 . 88 patients (23%) had a C-reactive protein (CRP) >5.0 µg/L.

CONCLUSION

Iron deficiency defined as ID_HF , ID_F100, or ID_Tsat is prevalent in the heart transplant population, while ID_F30 is not. Further research is required to identify the mechanisms of iron homeostasis in heart transplant recipients and to establish a definition of iron deficiency suitable for this population.

Ubiquitin-proteasome-system and enzymes of energy metabolism in skeletal muscle of patients with HFpEF and HFrEF

Background

Skeletal muscle (SM) alterations contribute to exercise intolerance in heart failure patients with preserved (HFpEF) or reduced (HFrEF) left ventricular ejection fraction (LVEF). Protein degradation via the ubiquitin‐proteasome‐system (UPS), nuclear apoptosis, and reduced mitochondrial energy supply is associated with SM weakness in HFrEF. These mechanisms are incompletely studied in HFpEF, and a direct comparison between these groups is missing.

Methods and results

Patients with HFpEF (LVEF ≥ 50%, septal E/e′ > 15 or >8 and NT‐proBNP > 220 pg/mL, n = 20), HFrEF (LVEF ≤ 35%, n = 20) and sedentary control subjects (Con, n = 12) were studied. Inflammatory markers were measured in serum, and markers of the UPS, nuclear apoptosis, and energy metabolism were determined in percutaneous SM biopsies. Both HFpEF and HFrEF showed increased proteolysis (MuRF‐1 protein expression, ubiquitination, and proteasome activity) with proteasome activity significantly related to interleukin‐6. Proteolysis was more pronounced in patients with lower exercise capacity as indicated by peak oxygen uptake in per cent predicted below the median. Markers of apoptosis did not differ between groups. Mitochondrial energy supply was reduced in HFpEF and HFrEF (complex‐I activity: −31% and −53%; malate dehydrogenase activity: −20% and −29%; both P < 0.05 vs. Con). In contrast, short‐term energy supply via creatine kinase was increased in HFpEF but decreased in HFrEF (47% and −45%; P < 0.05 vs. Con).

Conclusions

Similarly to HFrEF, skeletal muscle in HFpEF is characterized by increased proteolysis linked to systemic inflammation and reduced exercise capacity. Energy metabolism is disturbed in both groups; however, its regulation seems to be severity‐dependent.

Heart rate kinetics during standard cardiopulmonary exercise testing in heart transplant recipients: a longitudinal study

AIMS

Heart transplantation (HTx) results in complete autonomic denervation of the donor heart, causing resting tachycardia and abnormal heart rate (HR) responses to exercise. We determined the time course of suggestive cardiac reinnervation post HTx and investigated its clinical significance.

METHODS AND RESULTS

Heart rate kinetics during standard cardiopulmonary exercise testing at 2.5-5 years after HTx was assessed in 58 patients. According to their HR increase 30 s after exercise onset, HTx recipients were classified as denervated (slow responders: <5 beats per minute [b.p.m.]) or potentially reinnervated (fast responders: ≥5 b.p.m.). Additionally, in 30 patients, longitudinal changes of maximal oxygen consumption and HR kinetics were assessed during the first 15 post-operative years. At 2.5-5 years post HTx, 38% of our study population was potentially reinnervated. Fast responders were significantly younger (41 ± 15 years) than slow responders (53 ± 13 years, P = 0.003) but did not differ with regard to donor age, immunosuppressive regime, cardiovascular risk factors, endomyocardial biopsy, or vasculopathy parameters. While HR reserve (56 ± 20 vs. 39 ± 15 b.p.m., P = 0.002) and HR recovery after 60 s (15 ± 11 vs. 5 ± 6 b.p.m., P < 0.001) were greater in fast responders, resting HR, peak HR of predicted, and peak oxygen consumption of predicted were comparable.

CONCLUSIONS

Signs of reinnervation occurred mainly in younger patients. Maximal oxygen consumption was independent of HR kinetics.

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.

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.

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.

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 De Novo Heart Transplant Recipients in Scandinavia

BACKGROUND

There is no consensus on how, when, or at what intensity exercise should be performed after heart transplantation (HTx). We have recently shown that high-intensity interval training (HIT) is safe, well tolerated, and efficacious in the maintenance state after HTx, but studies have not investigated HIT effects in the de novo HTx state. We hypothesized that HIT could be introduced early after HTx and that it could lead to clinically meaningful increases in exercise capacity and health-related quality of life.

METHODS

This multicenter, prospective, randomized, controlled trial included 81 patients a mean of 11 weeks (range, 7-16 weeks) after an HTx. Patients were randomized 1:1 to 9 months of either HIT (4×4-minute intervals at 85%-95% of peak effort) or moderate-intensity continuous training (60%-80% of peak effort). The primary outcome was the effect of HIT versus moderate-intensity continuous training on the change in aerobic exercise capacity, assessed as the peak oxygen consumption (Vo₂peak). Secondary outcomes included tolerability, safety, adverse events, isokinetic muscular strength, body composition, health-related quality of life, left ventricular function, hemodynamics, endothelial function, and biomarkers.

RESULTS

From baseline to follow-up, 96% of patients completed the study. There were no serious exercise-related adverse events. The population comprised 73% men, and the mean±SD age was 49±13 years. At the 1-year follow-up, the HIT group demonstrated greater improvements than the moderate-intensity continuous training group; the groups showed significantly different changes in the Vo₂peak (mean difference between groups, 1.8 mL·kg^-1·min^-1), the anaerobic threshold (0.28 L/min), the peak expiratory flow (11%), and the extensor muscle exercise capacity (464 J). The 1.8-mL·kg^-1·min^-1 difference was equal to ≈0.5 metabolic equivalents, which is regarded as clinically meaningful and relevant. Health-related quality of life was similar between the groups, as indicated by results from the Short Form-36 (version 2), Hospital Anxiety and Depression Scale, and a visual analog scale.

CONCLUSIONS

We demonstrated that HIT was a safe, efficient exercise method in de novo HTx recipients. HIT, compared with moderate-intensity continuous training, resulted in a clinically significantly greater change in exercise capacity based on the Vo₂peak values (25% versus 15%), anaerobic threshold, peak expiratory flow, and muscular exercise capacity.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov . Unique identifier NCT01796379.

One-year follow-up of heart transplant recipient with cardiac rehabilitation: A case report

INTRODUCTION

Heart transplantation (HT) is known to be the final therapy for patients with advanced heart failure; however, the exercise capacity of these patients remains under the aged-predicted value after HT. Many studies have described the effectiveness and safety of cardiac rehabilitation (CR) in HT recipients. Nevertheless, long-term follow-up data of HT recipients undergoing CR are insufficient, and there is a lack of evidence on the long-term effects of CR. In this case report, we present the long-term benefits of CR in an HT recipient, including serial follow-up clinical data over 1 year.

PATIENT CONCERNS

A 48-year-old female patient underwent HT because of advanced dilated cardiomyopathy.

DIAGNOSIS

Cardiopulmonary exercise test showed reduced exercise capacity and pulmonary function. The grip power and quadriceps muscle strength were also decreased after HT.

INTERVENTIONS

The patient underwent a phase I CR program for 3 months, followed by a phase III CR program for 7 months. In the beginning, moderate-intensity continuous training was conducted. Thereafter, high-intensity interval training was implemented after a period of adjustment for interval training.

OUTCOMES

The exercise capacity, 6-min walk distance, muscle strength, and vital capacity were improved after CR.

CONCLUSION

CR in HT recipients may improve muscle strength and pulmonary function as well as exercise capacity, without serious cardiovascular complications. Phase III CR may help maintain exercise capacity in these patients.

Autonomic cardiovascular control changes in recent heart transplant recipients lead to physiological limitations in response to orthostatic challenge and isometric exercise

PURPOSE

Heart transplantation causes denervation of the donor heart, but the consequences for cardiovascular homeostasis remain to be fully understood. The present study investigated cardiovascular autonomic control at supine rest, during orthostatic challenge and during isometric exercise in heart transplant recipients (HTxR).

METHODS

A total of 50 HTxRs were investigated 7-12 weeks after transplant surgery and compared with 50 healthy control subjects. Continuous, noninvasive recordings of cardiovascular variables were carried out at supine rest, during 15 min of 60° head-up tilt and during 1 min of 30% of maximal voluntary handgrip. Plasma and urine catecholamines were assayed, and symptoms were charted.

RESULTS

At supine rest, heart rate, blood pressures and total peripheral resistance were higher, and stroke volume and end diastolic volume were lower in the HTxR group. During tilt, heart rate, blood pressures and total peripheral resistance increased less, and stroke volume and end diastolic volume decreased less. During handgrip, heart rate and cardiac output increased less, and stroke volume and end diastolic volume decreased less. Orthostatic symptoms were similar across the groups, but the HTxRs complained more of pale and cold hands.

CONCLUSION

HTxRs are characterized by elevated blood pressures and total peripheral resistance at supine rest as well as attenuated blood pressures and total peripheral resistance responses during orthostatic challenge, possibly caused by low-pressure cardiopulmonary baroreceptor denervation. In addition, HTxRs show attenuated cardiac output response during isometric exercise due to efferent sympathetic denervation. These physiological limitations might have negative functional consequences.

Exercise Training and Heart Failure: A Review of the Literature

Exercise and cardiac rehabilitation have been underused therapy options for patients with congestive heart failure despite being recommended in international guidelines and being covered by Medicare in the US. This article reviews the evidence behind this treatment strategy and details current trials that will contribute to the evidence base.

Obesity in patients with end-stage heart failure

Obesity poses an increasing problem in patients with end-stage heart failure (HF). The most commonly used indicator of obesity is body mass index. The value of this parameter is widely taken into consideration when selecting the best way of treatment for patients with advanced HF. The aim of this paper is to outline the recent knowledge about obesity in the abovementioned group of patients.

Clinical features and determinants of VO2peak in de novo heart transplant recipients

AIM

To study exercise capacity and determinants of early peak oxygen consumption (VO_2peak) in a cohort of de novo heart transplant (HTx) recipients.

METHODS

To determine possible central (chronotropic responses, cardiopulmonary and hemodynamic function) and peripheral factors (muscular exercise capacity and body composition) predictive of VO_2peak, a number of different measurements and tests were performed, as follows: Cardiopulmonary exercise testing (CPET) was performed mean 11 wk after surgery in 81 HTx recipients > 18 years and was measured with breath by breath gas exchange on a treadmill or bicycle ergometer. Metabolic/respiratory measures include VO_2peak and VE/VCO₂ slope. Additional measures included muscle strength testing, bioelectrical impedance analysis, echocardiography, blood sampling and health-related quality of life. Based on the VO_2peak (mL/kg per minute) median value, the study population was divided into two groups defined as a low-capacity group and a high-capacity group. Potential predictors were analyzed using multiple regression analysis with VO_2peak (L/min) as the dependent variable.

RESULTS

The mean ± standard deviation (SD) age of the total study population was 49 ± 13 years, and 73% were men. This de novo HTx cohort demonstrated a median VO_2peak level of 19.4 mL/kg per min at 11 ± 1.8 wk post-HTx. As compared with the high-capacity group, the low-capacity group exercised for a shorter time, had lower maximal ventilation, O₂ pulse, peak heart rate and heart rate reserve, while the VE/VCO₂ slope was higher. The low-capacity group had less muscle strength and muscular exercise capacity in comparison with the high-capacity group. In order of importance, O₂ pulse, heart rate reserve, muscular exercise capacity, body mass index, gender and age accounted for 84% of the variance in VO_2peak (L/min). There were no minor or major serious adverse events during the CPET.

CONCLUSION

Although there is great individual variance among de novo HTx recipients, early VO_2peak measures appear to be influenced by both central and peripheral factors.

Frailty in the End-Stage Lung Disease or Heart Failure Patient: Implications for the Perioperative Transplant Clinician

The syndrome of frailty for patients undergoing heart or lung transplantation has been a recent focus for perioperative clinicians because of its association with postoperative complications and poor outcomes. Patients with end-stage cardiac or pulmonary failure may be under consideration for heart or lung transplantation along with bridging therapies such as ventricular assist device implantation or venovenous extracorporeal membrane oxygenation, respectively. Early identification of frail patients in an attempt to modify the risk of postoperative morbidity and mortality has become an important area of study over the last decade. Many quantification tools and risk prediction models for frailty have been developed but have not been evaluated extensively or standardized in the cardiothoracic transplant candidate population. Heightened awareness of frailty, coupled with a better understanding of distinct cellular mechanisms and biomarkers apart from end-stage organ disease, may play an important role in potentially reversing frailty related to organ failure. Furthermore, the clinical management of these critically ill patients may be enhanced by waitlist and postoperative physical rehabilitation and nutritional optimization.

Physician Practice Patterns and Barriers to Counselling on Physical Activity in Solid Organ Transplant Recipients

Background

Many solid organ transplant (SOT) recipients fail to meet the recommended physical activity (PA) levels. “Physician recommendation” has previously been reported by SOT recipients as a key facilitator to being more physically active. The purpose of this study was to determine the proportion of Canadian SOT physicians providing PA counselling and identify barriers to including such counselling as part of the SOT recipients’ routine care.

Material/Methods

We conducted a cross-sectional web-based survey study to evaluate physicians’ PA counselling practices, including the prevalence and barriers to such practice. A survey link was sent to a convenience sample of transplant physicians who are members of the Canadian Society of Transplantation.

Results

Thirty-four physicians (13.6%) participated in the survey. While 97% (n=33) of the participants reported providing PA counselling to their transplant patients, only 18% (n=6) responded they were very confident in PA counselling. Lack of time (n=19; 56%) and a lack of exercise guidelines (n=18; 53%) were identified as the main barriers to PA counselling.

Conclusions

Incorporating sufficient PA knowledge into physicians’ educational curricula system, developing specific PA guidelines as well as establishing an easier referral system to exercise specialists might improve the frequency and quality of PA counselling post-transplant.

Improvements in exercise capacity following cardiac transplantation in a patient born with double inlet left ventricle

A 32-year-old man born with double inlet left ventricle (DILV) and other significant cardiac abnormalities underwent surgical palliation at 1 day, 2 years and 20 years, before receiving a donor heart at 29 years. To our knowledge, there are no case reports or cohort studies of the effect of exercise training on exercise capacity and peak oxygen uptake (VO2peak) following heart transplantation (HTx) for individuals born with DILV. The patient accessed our clinical exercise physiology service for assessment, advice and support for exercise training over a 7-year period spanning pre-HTx and post-HTx. An individualised exercise plan, together with careful assessment and monitoring, and the patient's own motivation have contributed to him achieving an outstanding post-HTx doubling of VO2peak and exercise capacity.

High-Intensity Interval Training in Heart Transplant Recipients: A Systematic Review with Meta-Analysis

Heart transplantation (HTx) is considered an efficient and gold-standard procedure for patients with end-stage heart failure. After surgery, patients have lower aerobic power (VO2max) and compensatory hemodynamic responses. The aim of the present study was to assess through a systematic review with meta-analysis whether high-intensity interval training (HIIT) can provide benefits for those parameters. This is a systematic review with meta-analysis, which searched the databases and data portals PubMed, Web of Science, Scopus, Science Direct and Wiley until December 2016 (pairs). The following terms and descriptors were used: "heart recipient" OR "heart transplant recipient" OR "heart transplant" OR "cardiac transplant" OR "heart graft". Descriptors via DeCS and Mesh were: "heart transplantation'' OR "cardiac transplantation". The words used in combination (AND) were: "exercise training" OR "interval training" OR "high intensity interval training" OR "high intensity training" OR "anaerobic training" OR "intermittent training" OR "sprint training". The initial search identified 1064 studies. Then, only those studies assessing the influence of HIIT on the post-HTx period were added, resulting in three studies analyzed. The significance level adopted was 0.05. Heart transplant recipients showed significant improvement in VO2peak, heart rate and peak blood pressure in 8 to 12 weeks of intervention.

A hybrid cardiac rehabilitation is as effective as a hospital-based program in reducing chest pain intensity and discomfort

Background

Health care services effort to provide alternative cardiac rehabilitation (CR) models to serve patients according to their preferences and needs. So, the present study aimed to assess and compare the effects of hospital-based and hybrid CR programs on chest pain intensity and discomfort in cardiac surgery patients.

Methods

In this prospective study, 110 cardiac surgery patients were invited to the CR department of a hospital in the western part of Iran between March and July 2016. Patients were divided into two groups: hospital-based and hybrid CR. The hospital-based program included 26 sessions, and the hybrid program included 10 training sessions and exercise. The Brief Pain Inventory and Pain Discomfort Scale were used as research instrument, and data were analyzed using the paired t-test and ANCOVA.

Results

The results indicated that both hospital-based and hybrid CR are effective in reducing the chest pain intensity and discomfort of cardiac surgery patients (P < 0.05). In addition, the comparison of scores before and after treatment using ANCOVA shows that no significant differences were observed between the two programs (P > 0.05).

Conclusions

Traditional hospital-based CR delivery is still the first choice for treatment in developing countries. However, hybrid CR is as effective as a hospital-based program in reducing pain components and it includes only 38% of the total cost in comparison to hospital-based delivery. So, we recommend using hybrid CR according with the recommendations of American Heart Association about using CR for the management of angina symptoms.

Anatomical visualization of neural course and distribution of anterior ascending aortic plexus

The aim of this study was to document the detailed anatomy of neural course and distribution on the anterior ascending aorta, to identify the high and low density areas of the anterior ascending aortic plexus for further understandings in cardiovascular surgery. The embalmed hearts of 42 elderly individuals were submacroscopically and microscopically examined, after excluding any that were macroscopically abnormal. With its origins in the anterior ascending aortic plexus, the right coronary plexus substantially innervated the right coronary artery, the right atrium and ventricle, and the sinus node. The intensive neural area extending from 10 mm lateral to the interatrial groove below the pericardial reflection as far as the right coronary artery opening contained almost all the right coronary plexus in 61.3% of patients, and more than 40.9% of the total nerve volume of the anterior ascending aortic plexus. Our findings suggest that the most superior and lateral area on the ascending aorta show the lowest neural density of right coronary component in the anterior ascending aortic plexus and the high density areas are invisible in right lateral field of view as seen in the right trans-axillary MICS approach.

Exercise And Heart Failure: Advancing Knowledge And Improving Care

Exercise limitation is the hallmark of heart failure, and an increasing degree of intolerance is associated with poor prognosis. Objective evaluation of functional class (e.g., cardiopulmonary exercise testing) is essential for adequate prognostication in patients with advanced heart failure and for implementing an appropriate exercise training program. A graded exercise program has been shown to be beneficial in patients with heart failure and has become an essential component of comprehensive cardiac rehabilitation in these patients. An exercise program tailored to the patient's preferences, possibilities, and physiologic reserve has the greatest chance of being successful. Despite being safe, effective, and a guideline-recommended treatment to improve quality of life, exercise training remains grossly underutilized. Patient, physician, insurance and practice barriers need to be addressed to improve this quality gap.

Exercise-based cardiac rehabilitation in heart transplant recipients

BACKGROUND

Heart transplantation is considered to be the gold standard treatment for selected patients with end-stage heart disease when medical therapy has been unable to halt progression of the underlying pathology. Evidence suggests that aerobic exercise training may be effective in reversing the pathophysiological consequences associated with cardiac denervation and prevent immunosuppression-induced adverse effects in heart transplant recipients.

OBJECTIVES

To determine the effectiveness and safety of exercise-based rehabilitation on the mortality, hospital admissions, adverse events, exercise capacity, health-related quality of life, return to work and costs for people after heart transplantation.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, MEDLINE (Ovid), Embase (Ovid), CINAHL (EBSCO) and Web of Science Core Collection (Thomson Reuters) to June 2016. We also searched two clinical trials registers and handsearched the reference lists of included studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of parallel group, cross-over or cluster design, which compared exercise-based interventions with (i) no exercise control (ii) a different dose of exercise training (e.g. low- versus high-intensity exercise training); or (iii) an active intervention (i.e. education, psychological intervention). The study population comprised adults aged 18 years or over who had received a heart transplant.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all identified references for inclusion based on pre-specified inclusion criteria. Disagreements were resolved by consensus or by involving a third person. Two review authors extracted outcome data from the included trials and assessed their risk of bias. One review author extracted study characteristics from included studies and a second author checked them against the trial report for accuracy.

MAIN RESULTS

We included 10 RCTs that involved a total of 300 participants whose mean age was 54.4 years. Women accounted for fewer than 25% of all study participants. Nine trials which randomised 284 participants to receive exercise-based rehabilitation (151 participants) or no exercise (133 participants) were included in the main analysis. One cross-over RCT compared high-intensity interval training with continued moderate-intensity training in 16 participants. We reported findings for all trials at their longest follow-up (median 12 weeks).Exercise-based cardiac rehabilitation increased exercise capacity (VO_2peak) compared with no exercise control (MD 2.49 mL/kg/min, 95% CI 1.63 to 3.36; N = 284; studies = 9; moderate quality evidence). There was evidence from one trial that high-intensity interval exercise training was more effective in improving exercise capacity than continuous moderate-intensity exercise (MD 2.30 mL/kg/min, 95% CI 0.59 to 4.01; N = 16; 1 study). Four studies reported health-related quality of life (HRQoL) measured using SF-36, Profile of Quality of Life in the Chronically Ill (PLC) and the World Health Organization Quality Of Life (WHOQoL) - BREF. Due to the variation in HRQoL outcomes and methods of reporting we were unable to meta-analyse results across studies, but there was no evidence of a difference between exercise-based cardiac rehabilitation and control in 18 of 21 HRQoL domains reported, or between high and moderate intensity exercise in any of the 10 HRQoL domains reported. One adverse event was reported by one study.Exercise-based cardiac rehabilitation improves exercise capacity, but exercise was found to have no impact on health-related quality of life in the short-term (median 12 weeks follow-up), in heart transplant recipients whose health is stable.There was no evidence of statistical heterogeneity across trials for exercise capacity and no evidence of small study bias. The overall risk of bias in included studies was judged as low or unclear; more than 50% of included studies were assessed at unclear risk of bias with respect to allocation concealment, blinding of outcome assessors and declaration of conflicts of interest. Evidence quality was assessed as moderate according to GRADE criteria.

AUTHORS' CONCLUSIONS

We found moderate quality evidence suggesting that exercise-based cardiac rehabilitation improves exercise capacity, and that exercise has no impact on health-related quality of life in the short-term (median 12 weeks follow-up), in heart transplant recipients. Cardiac rehabilitation appears to be safe in this population, but long-term follow-up data are incomplete and further good quality and adequately-powered trials are needed to demonstrate the longer-term benefits of exercise on safety and impact on both clinical and patient-related outcomes, such as health-related quality of life, and healthcare costs.

Exercise-based cardiac rehabilitation in heart transplant recipients

BACKGROUND

Heart transplantation is considered to be the gold standard treatment for selected patients with end-stage heart disease when medical therapy has been unable to halt progression of the underlying pathology. Evidence suggests that aerobic exercise training may be effective in reversing the pathophysiological consequences associated with cardiac denervation and prevent immunosuppression-induced adverse effects in heart transplant recipients.

OBJECTIVES

To determine the effectiveness and safety of exercise-based rehabilitation on the mortality, hospital admissions, adverse events, exercise capacity, health-related quality of life, return to work and costs for people after heart transplantation.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, MEDLINE (Ovid), Embase (Ovid), CINAHL (EBSCO) and Web of Science Core Collection (Thomson Reuters) to June 2016. We also searched two clinical trials registers and handsearched the reference lists of included studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of parallel group, cross-over or cluster design, which compared exercise-based interventions with (i) no exercise control (ii) a different dose of exercise training (e.g. low- versus high-intensity exercise training); or (iii) an active intervention (i.e. education, psychological intervention). The study population comprised adults aged 18 years or over who had received a heart transplant.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all identified references for inclusion based on pre-specified inclusion criteria. Disagreements were resolved by consensus or by involving a third person. Two review authors extracted outcome data from the included trials and assessed their risk of bias. One review author extracted study characteristics from included studies and a second author checked them against the trial report for accuracy.

MAIN RESULTS

We included 10 RCTs that involved a total of 300 participants whose mean age was 54.4 years. Women accounted for fewer than 25% of all study participants. Nine trials which randomised 284 participants to receive exercise-based rehabilitation (151 participants) or no exercise (133 participants) were included in the main analysis. One cross-over RCT compared high-intensity interval training with continued moderate-intensity training in 16 participants. We reported findings for all trials at their longest follow-up (median 12 weeks).Exercise-based cardiac rehabilitation increased exercise capacity (VO2peak) compared with no exercise control (MD 2.49 mL/kg/min, 95% CI 1.63 to 3.36; N = 284; studies = 9; moderate quality evidence). There was evidence from one trial that high-intensity interval exercise training was more effective in improving exercise capacity than continuous moderate-intensity exercise (MD 2.30 mL/kg/min, 95% CI 0.59 to 4.01; N = 16; 1 study). Four studies reported health-related quality of life (HRQoL) measured using SF-36, Profile of Quality of Life in the Chronically Ill (PLC) and the World Health Organization Quality Of Life (WHOQoL) - BREF. Due to the variation in HRQoL outcomes and methods of reporting we were unable to meta-analyse results across studies, but there was no evidence of a difference between exercise-based cardiac rehabilitation and control in 18 of 21 HRQoL domains reported, or between high and moderate intensity exercise in any of the 10 HRQoL domains reported. One adverse event was reported by one study.Exercise-based cardiac rehabilitation improves exercise capacity, but exercise was found to have no impact on health-related quality of life in the short-term (median 12 weeks follow-up), in heart transplant recipients whose health is stable.There was no evidence of statistical heterogeneity across trials for exercise capacity and no evidence of small study bias. The overall risk of bias in included studies was judged as low or unclear; more than 50% of included studies were assessed at unclear risk of bias with respect to allocation concealment, blinding of outcome assessors and declaration of conflicts of interest. Evidence quality was assessed as moderate according to GRADE criteria.

AUTHORS' CONCLUSIONS

We found moderate quality evidence suggesting that exercise-based cardiac rehabilitation improves exercise capacity, and that exercise has no impact on health-related quality of life in the short-term (median 12 weeks follow-up), in heart transplant recipients. Cardiac rehabilitation appears to be safe in this population, but long-term follow-up data are incomplete and further good quality and adequately-powered trials are needed to demonstrate the longer-term benefits of exercise on safety and impact on both clinical and patient-related outcomes, such as health-related quality of life, and healthcare costs.

Design and rationale of the HITTS randomized controlled trial: Effect of High-intensity Interval Training in de novo Heart Transplant Recipients in Scandinavia

There is no consensus on how, when, and at what intensity exercise should be performed and organized after heart transplantation (HTx). Most rehabilitation programs are conducted in HTx centers, which might be impractical and costly. We have recently shown that high-intensity interval training (HIT) is safe, well tolerated, and efficacious in maintenance HTx recipients, but there are no studies among de novo patients, and whether HIT is feasible and superior to moderate training in HTx recipients is unclear. A total of 120 clinically stable HTx recipients older than 18 years will be recruited from 3 Scandinavian HTx centers. Participants are randomized to HIT or moderate training, shortly after surgery. All exercises are supervised in the patients' local communities. Testing at baseline and follow-up includes the following: VO2peak (primary end point), muscle strength, body composition, quality of life, myocardial performance, endothelial function, biomarkers, and progression of cardiac allograft vasculopathy. A subgroup (n = 90) will also be tested at 3-year follow-up to assess long-term effects of exercise. So far, the HIT intervention is well tolerated, without any serious adverse events. We aim to test whether decentralized HIT is feasible, safe, and superior to moderate training, and whether it will lead to significant improvement in exercise capacity and less long-term complications.

Peak oxygen uptake and self-reported physical health are strong predictors of long-term survival after heart transplantation

BACKGROUND

Peak oxygen uptake (VO2peak ) is known as the gold standard measure of cardiopulmonary fitness. We therefore hypothesized that measures of physical health would predict long-term survival in heart transplant recipients (HTx).

METHODS

This retrospective study investigated survival in two HTx populations; the cardiopulmonary exercise test (CPET) cohort comprised 178 HTx patients who completed a VO2peak test during their annual follow-up (1990-2003), and the SF-36 cohort comprised 133 patients who completed a quality of life questionnaire, SF-36v1 (1998-2000).

RESULTS

Mean (SD) age in the CPET cohort was 52 (12) yr and 54 (11) yr in the SF-36 cohort. Mean observation time was, respectively, 11 and 10 yr. Mean (SD) VO2peak was 19.6 (5.3) mL/kg/min, and median (IR) physical function (PF) score was 90 (30). VO2peak and PF scores were both significant predictors in univariate Cox regression. Multiple Cox regression analyses adjusted for other potential predictors showed that VO2peak , age, and cardiac allograft vasculopathy (CAV) were the most important predictors in the CPET cohort, whereas age, PF score, smoking, and CAV were the most important predictors in the SF-36 cohort. In Kaplan-Meier analysis, VO2peak and PF scores above the median value were related to significant longer survival time.

CONCLUSION

Peak oxygen uptake and self-reported physical health are strong predictors for long-term survival in HTx recipients. VO2peak is a crucial measurement and should be more frequently used after HTx.