Effects of exercise-based cardiac rehabilitation on cardiorespiratory fitness: A meta-analysis of UK studies

Effects of Exercise Training Response on Quality of Life and Cardiovascular Risk Factor Profiles in People With Coronary Artery Disease: Insights From the HIIT or MISS UK Trial

OBJECTIVE

To compare the characteristics of responders and nonresponders to 8 weeks of exercise training to determine differences in key cardiovascular disease outcomes in people with coronary artery disease (CAD).

DESIGN

Secondary analysis of data from the HIIT or MISS UK trial.

SETTING

Six outpatient National Health Service cardiac rehabilitation (CR) centers in the UK. In people with CAD attending CR, the HIIT or MISS UK trial reported that short-term, low-volume, high-intensity interval training (HIIT) was more effective than moderate-intensity steady state (MISS) exercise training for improving peak oxygen uptake (V̇o2peak).

PARTICIPANTS

382 participants with CAD (N=382) (mean age: 58.8±9.6y; mean body mass index: 29.0±4.3 kg/m2).

MAIN OUTCOME MEASURES

We identified responders and nonresponders based on a meaningful change in V̇o2peak, using 2 established methods. Key clinical, quality of life (QoL), and cardiopulmonary exercise test (CPET)-derived outcomes were compared between groups.

RESULTS

Responders were more likely to be younger (P<.05), and demonstrate greater improvement in CPET-related outcomes, for example, oxygen uptake efficiency slope, ventilatory efficiency, and peak power output (all comparisons, P<.001). Responders were more likely to observe improvements in QoL (EQ-5D-5L; mean Δ 13.6 vs mean Δ 9.4; P=.045), and high-density lipoprotein cholesterol (HDL-c) (mean Δ 0.09 mmol/L vs mean Δ 0.04 mmol/L; P=.004), compared to nonresponders.

CONCLUSIONS

In people with CAD attending CR, responders to exercise training were more likely to be younger and demonstrate greater improvements in health-related QoL and HDL-c.

Cardiac Rehabilitation and Risk of Incident Atrial Fibrillation in Patients with Coronary Artery Disease

BACKGROUND

Patients with coronary artery disease (CAD) are at risk for developing atrial fibrillation (AF). Whether attending a cardiac rehabilitation (CR) program can attenuate this risk is unclear.

METHODS

This retrospective cohort study included patients who were free of pre-existing AF and referred to CR after coronary revascularization between April 2004 and March 2015 in Calgary, Canada. Patients with incident AF were identified using administrative data and the local electrocardiogram repository. Exposure variables and covariates were extracted from electronic medical records of a CR program and a clinical registry.

RESULTS

The study included 11,662 patients [mean age (standard deviation), 60.9 (10.9) years; male, 80.6%]. In a median follow-up of 4.8 years, the cumulative incidence rate of AF was 1.04 per 100 person-years. There was no association between CR completion and the risk of incident AF after adjusting for baseline characteristics [Hazard ratio (HR): 0.97; 95% confidence interval (CI): 0.83-1.15]. However, each higher metabolic equivalent (MET) of baseline cardiorespiratory fitness (CRF) and each MET gain in CRF following CR were independently associated with a 12% (95% CI: 6%-18%) and 18% (95% CI: 6%-28%) lower relative risk of incident AF, respectively. The risk of incident AF declined progressively with the baseline CRF increasing up to 9.0 peak METs, and with the 12-week CRF increasing up to 10.3 peak METs; beyond these peak MET levels, benefits plateaued.

CONCLUSIONS

CR completion alone was not associated with a lower risk of incident AF. However, higher baseline CRF and greater CRF improvement had dose-dependent protective effects.

Optimizing Outcomes in Cardiac Rehabilitation: The Importance of Exercise Intensity

Exercise based cardiac rehabilitation (CR) is recognized internationally as a class 1 clinical practice recommendation for patients with select cardiovascular diseases and heart failure with reduced ejection fraction. Over the past decade, several meta-analyses have generated debate regarding the effectiveness of exercise-based CR for reducing all-cause and cardiovascular mortality. A common theme highlighted in these meta-analyses is the heterogeneity and/or lack of detail regarding exercise prescription methodology within CR programs. Currently there is no international consensus on exercise prescription for CR, and exercise intensity recommendations vary considerably between countries from light-moderate intensity to moderate intensity to moderate-vigorous intensity. As cardiorespiratory fitness [peak oxygen uptake (VO₂peak)] is a strong predictor of mortality in patients with coronary heart disease and heart failure, exercise prescription that optimizes improvement in cardiorespiratory fitness and exercise capacity is a critical consideration for the efficacy of CR programming. This review will examine the evidence for prescribing higher-intensity aerobic exercise in CR, including the role of high-intensity interval training. This discussion will highlight the beneficial physiological adaptations to pulmonary, cardiac, vascular, and skeletal muscle systems associated with moderate-vigorous exercise training in patients with coronary heart disease and heart failure. Moreover, this review will propose how varying interval exercise protocols (such as short-duration or long-duration interval training) and exercise progression models may influence central and peripheral physiological adaptations. Importantly, a key focus of this review is to provide clinically-relevant recommendations and strategies to optimize prescription of exercise intensity while maximizing safety in patients attending CR programs.

Effectiveness of comprehensive cardiac rehabilitation in coronary artery disease patients treated according to contemporary evidence based medicine: Update of the Cardiac Rehabilitation Outcome Study (CROS-II)

Background

Despite numerous studies and meta-analyses the prognostic effect of cardiac rehabilitation is still under debate. This update of the Cardiac Rehabilitation Outcome Study (CROS II) provides a contemporary and practice focused approach including only cardiac rehabilitation interventions based on published standards and core components to evaluate cardiac rehabilitation delivery and effectiveness in improving patient prognosis.

Design

A systematic review and meta-analysis.

Methods

Randomised controlled trials and retrospective and prospective controlled cohort studies evaluating patients after acute coronary syndrome, coronary artery bypass grafting or mixed populations with coronary artery disease published until September 2018 were included.

Results

Based on CROS inclusion criteria out of 7096 abstracts six additional studies including 8671 patients were identified (two randomised controlled trials, two retrospective controlled cohort studies, two prospective controlled cohort studies). In total, 31 studies including 228,337 patients were available for this meta-analysis (three randomised controlled trials, nine prospective controlled cohort studies, 19 retrospective controlled cohort studies; 50,653 patients after acute coronary syndrome 14,583, after coronary artery bypass grafting 163,101, mixed coronary artery disease populations; follow-up periods ranging from 9 months to 14 years). Heterogeneity in design, cardiac rehabilitation delivery, biometrical assessment and potential confounders was considerable. Controlled cohort studies showed a significantly reduced total mortality (primary endpoint) after cardiac rehabilitation participation in patients after acute coronary syndrome (prospective controlled cohort studies: hazard ratio (HR) 0.37, 95% confidence interval (CI) 0.20–0.69; retrospective controlled cohort studies HR 0.64, 95% CI 0.53–0.76; prospective controlled cohort studies odds ratio 0.20, 95% CI 0.08–0.48), but the single randomised controlled trial fulfilling the CROS inclusion criteria showed neutral results. Cardiac rehabilitation participation was also associated with reduced total mortality in patients after coronary artery bypass grafting (retrospective controlled cohort studies HR 0.62, 95% CI 0.54–0.70, one single randomised controlled trial without fatal events), and in mixed coronary artery disease populations (retrospective controlled cohort studies HR 0.52, 95% CI 0.36–0.77; two out of 10 controlled cohort studies with neutral results).

Conclusion

CROS II confirms the effectiveness of cardiac rehabilitation participation after acute coronary syndrome and after coronary artery bypass grafting in actual clinical practice by reducing total mortality under the conditions of current evidence-based coronary artery disease treatment. The data of CROS II, however, underscore the urgent need to define internationally accepted minimal standards for cardiac rehabilitation delivery as well as for scientific evaluation.

A comparison of high versus low dose of exercise training in exercise-based cardiac rehabilitation: a randomized controlled trial with 12-months follow-up

OBJECTIVE

To assess if a higher dose of exercise training in exercise-based cardiac rehabilitation could affect improvements in aerobic capacity and muscle strength.

DESIGN

Assessor-blinded randomized controlled trial with 12-months follow-up.

SETTING

Aarhus University Hospital, Aarhus, Denmark.

SUBJECTS

A total of 164 cardiac patients referred to exercise-based cardiac rehabilitation were recruited.

INTERVENTIONS

Patients were randomized to 1-hour exercise sessions either three times weekly for 12 weeks (36 sessions, high-dose group) or twice weekly for 8 weeks (16 sessions, low-dose group). The same standardized exercise and intensity protocol including aerobic and muscle strength training was used in all participants.

MAIN MEASURES

Primary outcome was changes in VO_2peak. Secondary outcomes were changes in maximal workload, muscle strength and power. Measures were obtained at baseline, after termination of the rehabilitation programme and at follow-up after 6 and 12 months.

RESULTS

After the end of intervention, statistically significant between-group differences were seen in favour of the high-dose group in all outcomes: VO_2peak 2.6 (mL kg^-1 min^-1) (95% confidence interval (CI): 0.4-4.8), maximal workload 0.3 W kg^-1 (95%CI: 0.02-0.5), isometric muscle strength 0.7 N m kg^-1 (95%CI: 0.1-1.2) and muscle power 0.3 W kg^-1 (95%CI: 0.04-0.6). After 12 months, a significant between-group difference only persisted in VO_2peak and maximal workload.

CONCLUSION

A higher dose of exercise training had a small effect on all outcomes at termination of intervention. A long-term effect persisted in VO_2peak and maximal workload. Although the effect was small, it is an important finding because VO_2peak is the most important predictor of all-cause mortality in cardiac patients.

Cardiac Rehabilitation for Secondary Prevention of Cardiovascular Disease: 2019 Update

PURPOSE OF REVIEW

To provide updated information on the science and practice of cardiac rehabilitation (CR).

RECENT FINDINGS

Evidence continues to mount that supports the many benefits of CR as well as the important gap in delivering CR to all eligible patients. Recent studies have identified center-based and home-based strategies to improve the reach and impact of CR. Cardiac rehabilitation is a systematic, evidence-based approach to deliver effective secondary CVD preventive therapies to individuals with cardiovascular conditions. Because of a number of benefits that have been associated with CR, clinical practice guidelines strongly endorse CR services for eligible patients. Research supports CR as a high value service, with evidence of favorable clinical outcomes and costs. Unfortunately, a significant gap exists in CR participation due to a number of patient-, provider-, and system-level barriers. Solutions to most of these barriers have been identified and involve systematic approaches to CR delivery. The future is bright for CR as new strategies, new policies, and new methods of delivery continue to develop to help provide CR services to all eligible patients.

Insufficient exercise intensity for clinical benefit? Monitoring and quantification of a community-based Phase III cardiac rehabilitation programme: A United Kingdom perspective

BACKGROUND

In recent years, criticism of the percentage range approach for individualised exercise prescription has intensified and we were concerned that sub-optimal exercise dose (especially intensity) may be in part responsible for the variability in the effectiveness of cardiac rehabilitation (CR) programmes in the United Kingdom (UK). The aim was to investigate the fidelity of a structured Phase III CR programme, by monitoring and quantifying exercise training intensity.

DESIGN

Observational study.

METHODS

The programme comprised 16 sessions over 8 weeks, where patients undertook an interval, circuit training approach within national guidelines for exercise prescription (40-70% heart rate reserve [HRR]). All patients wore an Apple Watch (Series 0 or 2, Watch OS2.0.1, Apple Inc., California, USA). We compared the mean % heart rate reserve (%HRR) achieved during the cardiovascular training component (%HRR-CV) of a circuit-based programme, with the %HRR during the active recovery phases (%HRR-AR) in a randomly selected cohort of patients attending standard CR. We then compared the mean %HRR-CV achieved with the minimal exercise intensity threshold during supervised exercise (40% HRR) recommended by national governing bodies.

RESULTS

Thirty cardiac patients (83% male; mean age [SD] 67 [10] years; BMI 28.3 [4.6] kg∙m-2) were recruited. We captured 332 individual training sessions. The mean %HRR-CV and %HRR-AR were 37 (10) %, and 31 (13) %, respectively. There was weak evidence to support the alternative hypothesis of a difference between the %HRR-CV and 40% HRR. There was very strong evidence to accept the alternative hypothesis that the mean %HRR-AR was lower than the mean %HRR-CV, median standardised effect size 1.1 (95%CI: 0.563 to 1.669), with a moderate to large effect.

CONCLUSION

Mean exercise training intensity was below the lower limit of the minimal training intensity guidelines for a Phase III CR programme. These findings may be in part responsible for previous reports highlighting the significant variability in effectiveness of UK CR services and poor CRF improvements observed from several prior investigations.

What is the effect of aerobic exercise intensity on cardiorespiratory fitness in those undergoing cardiac rehabilitation? A systematic review with meta-analysis

OBJECTIVE

Assess the role of exercise intensity on changes in cardiorespiratory fitness (CRF) in patients with cardiac conditions attending exercise-based cardiac rehabilitation.

DESIGN

Systematic review with meta-analysis.

DATA SOURCES

MEDLINE, Embase, CINAHL, SPORTDiscus, PsycINFO and Web of Science.

ELIGIBILITY CRITERIA FOR SELECTION

Studies assessing change in CRF (reported as peak oxygen uptake; V̇O_2peak) in patients post myocardial infarction and revascularisation, following exercise-based cardiac rehabilitation. Studies establishing V̇O_2peak via symptom-limited exercise test with ventilatory gas analysis and reported intensity of exercise during rehabilitation were included. Studies with mean ejection fraction <40% were excluded.

RESULTS

128 studies including 13 220 patients were included. Interventions were classified as moderate, moderate-to-vigorous or vigorous intensity based on published recommendations. Moderate and moderate-to-vigorous-intensity interventions were associated with a moderate increase in relative V̇O_2peak (standardised mean difference±95% CI=0.94±0.30 and 0.93±0.17, respectively), and vigorous-intensity exercise with a large increase (1.10±0.25). Moderate and vigorous-intensity interventions were associated with moderate improvements in absoluteV̇O_2peak (0.63±0.34 and 0.93±0.20, respectively), whereas moderate-to-vigorous-intensity interventions elicited a large effect (1.27±0.75). Large heterogeneity among studies was observed for all analyses. Subgroup analyses yielded statistically significant, but inconsistent, improvements in CRF.

CONCLUSION

Engagement in exercise-based cardiac rehabilitation was associated with significant improvements in both absolute and relative V̇O_2peak. Although exercise of vigorous intensity produced the greatest pooled effect for change in relative V̇O_2peak, differences in pooled effects between intensities could not be considered clinically meaningful.

REGISTRATION

Prospero CRD42016035638.

Association of Neighborhood Socioeconomic Context With Participation in Cardiac Rehabilitation

BACKGROUND

Cardiac rehabilitation (CR) is underutilized in the United States, with fewer than 20% of eligible patients participating in CR programs. Individual socioeconomic status is associated with CR utilization, but data regarding neighborhood characteristics and CR are sparse. We investigated the association of neighborhood socioeconomic context with CR participation in the SCCS (Southern Community Cohort Study).

METHODS AND RESULTS

The SCCS is a prospective cohort study of 84 569 adults in the southeastern United States from 2002 to 2009, 52 117 of whom have Medicare or Medicaid claims. Using these data, we identified participants with hospitalizations for myocardial infarction, percutaneous coronary intervention, or coronary artery bypass surgery and ascertained their CR utilization. Neighborhood socioeconomic context was assessed using a neighborhood deprivation index derived from 11 census-tract level variables. We analyzed the association of CR utilization with neighborhood deprivation after adjusting for individual socioeconomic status. A total of 4096 SCCS participants (55% female, 57% black) with claims data were eligible for CR. CR utilization was low, with 340 subjects (8%) participating in CR programs. Study participants residing in the most deprived communities (highest quintile of neighborhood deprivation) were less than half as likely to initiate CR (odds ratio 0.42, 95% confidence interval, 0.27-0.66, P<0.001) as those in the lowest quintile. CR participation was inversely associated with all-cause mortality (hazard ratio 0.77, 95% confidence interval, 0.60-0.996, P<0.05).

CONCLUSIONS

Lower neighborhood socioeconomic context was associated with decreased CR participation independent of individual socioeconomic status. These data invite research on interventions to increase CR access in deprived communities.

Exercise dose and all-cause mortality within extended cardiac rehabilitation: a cohort study

Aims

To investigate the relationship between exercise participation, exercise ‘dose’ expressed as metabolic equivalent (MET) hours (h) per week, and prognosis in individuals attending an extended, community-based exercise rehabilitation programme.

Methods

Cohort study of 435 participants undertaking exercise-based cardiac rehabilitation (CR) in Leeds, West Yorkshire, UK between 1994 and 2006, followed up to 1 November 2013. MET intensity of supervised exercise was estimated utilising serial submaximal exercise test results and corresponding exercise prescriptions. Programme participation was routinely monitored. Cox regression analysis including time-varying and propensity score adjustment was applied to identify predictors of long-term, all-cause mortality across exercise dose and programme duration groups.

Results

There were 133 events (31%) during a median follow-up of 14 years (range, 1.2 to 18.9 years). The significant univariate association between exercise dose and all-cause mortality was attenuated following multivariable adjustment for other predictors, including duration in the programme. Longer-term adherence to supervised exercise training (>36 months) was associated with a 33% lower mortality risk (multivariate-adjusted HR: 0.67; 95% CI: 0.47 to 0.97; p=0.033) compared with all lesser durations of CR (3, 12, 36 months), even after adjustment for baseline fitness, comorbidities and survivor bias.

Conclusion

Exercise dose (MET-h per week) appears less important than long-term adherence to supervised exercise for the reduction of long-term mortality risk. Extended, supervised CR programmes within the community may play a key role in promoting long-term exercise maintenance and other secondary prevention therapies for survival benefit.

Is the Comparison between Exercise and Pharmacologic Treatment of Depression in the Clinical Practice Guideline of the American College of Physicians Evidence-Based?

Major depression disorder is most commonly treated with antidepressants. However, due to their side effects clinicians seek non-pharmacologic options, and one of these is exercise. The literature on the benefits of exercise for depression is extensive. Nevertheless, two recent reviews focusing on antidepressants vs. other therapies as a basis for clinical practice guidelines recommended mainly antidepressants, excluding exercise as a viable choice for treatment of depression. The aim of this perspective is to analyze the literature exploring the reasons for this discrepancy. Two categories of publications were examined: randomized controlled trials (RCTs) and meta-analyses or systematic reviews. Based on this reassessment, RCTs comparing exercise to antidepressants reported that exercise and antidepressants were equally effective. RCTs comparing exercise combined with antidepressants to antidepressants only reported a significant improvement in depression following exercise as an adjunctive treatment. Almost all the reviews examining exercise vs. other treatments of depression, including antidepressants, support the use of exercise in the treatment of depression, at least as an adjunctive therapy. The two reviews examining pharmacologic vs. non-pharmacologic therapies as a basis for clinical practice guidelines examined limited evidence on exercise vs. antidepressants. In addition, it is possible that academics and health care practitioners are skeptical of viewing exercise as medicine. Maybe, there is a reluctance to accept that changes in lifestyle as opposed to pharmacological treatment can alter biological mechanisms. Longitudinal studies are needed for assessing the effectiveness of exercise in real clinical settings, as well as studies exploring dose-response relationship between exercise and depression.