Impact of different exercise training modalities on the coronary collateral circulation and plaque composition in patients with significant coronary artery disease (EXCITE trial): study protocol for a randomized controlled trial

Exercise-based cardiac rehabilitation for coronary heart disease

BACKGROUND

Coronary heart disease (CHD) is the most common cause of death globally. However, with falling CHD mortality rates, an increasing number of people living with CHD may need support to manage their symptoms and prognosis. Exercise-based cardiac rehabilitation (CR) aims to improve the health and outcomes of people with CHD. This is an update of a Cochrane Review previously published in 2016.

OBJECTIVES

To assess the clinical effectiveness and cost-effectiveness of exercise-based CR (exercise training alone or in combination with psychosocial or educational interventions) compared with 'no exercise' control, on mortality, morbidity and health-related quality of life (HRQoL) in people with CHD.

SEARCH METHODS

We updated searches from the previous Cochrane Review, by searching CENTRAL, MEDLINE, Embase, and two other databases in September 2020. We also searched two clinical trials registers in June 2021.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of exercise-based interventions with at least six months' follow-up, compared with 'no exercise' control. The study population comprised adult men and women who have had a myocardial infarction (MI), coronary artery bypass graft (CABG) or percutaneous coronary intervention (PCI), or have angina pectoris, or coronary artery disease.

DATA COLLECTION AND ANALYSIS

We screened all identified references, extracted data and assessed risk of bias according to Cochrane methods. We stratified meta-analysis by duration of follow-up: short-term (6 to 12 months); medium-term (> 12 to 36 months); and long-term ( > 3 years), and used meta-regression to explore potential treatment effect modifiers. We used GRADE for primary outcomes at 6 to 12 months (the most common follow-up time point).  MAIN RESULTS: This review included 85 trials which randomised 23,430 people with CHD. This latest update identified 22 new trials (7795 participants). The population included predominantly post-MI and post-revascularisation patients, with a mean age ranging from 47 to 77 years. In the last decade, the median percentage of women with CHD has increased from 11% to 17%, but females still account for a similarly small percentage of participants recruited overall ( < 15%). Twenty-one of the included trials were performed in low- and middle-income countries (LMICs). Overall trial reporting was poor, although there was evidence of an improvement in quality over the last decade. The median longest follow-up time was 12 months (range 6 months to 19 years). At short-term follow-up (6 to 12 months), exercise-based CR likely results in a slight reduction in all-cause mortality (risk ratio (RR) 0.87, 95% confidence interval (CI) 0.73 to 1.04; 25 trials; moderate certainty evidence), a large reduction in MI (RR 0.72, 95% CI 0.55 to 0.93; 22 trials; number needed to treat for an additional beneficial outcome (NNTB) 75, 95% CI 47 to 298; high certainty evidence), and a large reduction in all-cause hospitalisation (RR 0.58, 95% CI 0.43 to 0.77; 14 trials;  NNTB 12, 95% CI 9 to 21; moderate certainty evidence). Exercise-based CR likely results in little to no difference in risk of cardiovascular mortality (RR 0.88, 95% CI 0.68 to 1.14; 15 trials; moderate certainty evidence), CABG (RR 0.99, 95% CI 0.78 to 1.27; 20 trials; high certainty evidence), and PCI (RR 0.86, 95% CI 0.63 to 1.19; 13 trials; moderate certainty evidence) up to 12 months' follow-up. We are uncertain about the effects of exercise-based CR on cardiovascular hospitalisation, with a wide confidence interval including considerable benefit as well as harm (RR 0.80, 95% CI 0.41 to 1.59; low certainty evidence). There was evidence of substantial heterogeneity across trials for cardiovascular hospitalisations (I2 = 53%), and of small study bias for all-cause hospitalisation, but not for all other outcomes. At medium-term follow-up, although there may be little to no difference in all-cause mortality (RR 0.90, 95% CI 0.80 to 1.02; 15 trials), MI (RR 1.07, 95% CI 0.91 to 1.27; 12 trials), PCI (RR 0.96, 95% CI 0.69 to 1.35; 6 trials), CABG (RR 0.97, 95% CI 0.77 to 1.23; 9 trials), and all-cause hospitalisation (RR 0.92, 95% CI 0.82 to 1.03; 9 trials), a large reduction in cardiovascular mortality was found (RR 0.77, 95% CI 0.63 to 0.93; 5 trials). Evidence is uncertain for difference in risk of cardiovascular hospitalisation (RR 0.92, 95% CI 0.76 to 1.12; 3 trials). At long-term follow-up, although there may be little to no difference in all-cause mortality (RR 0.91, 95% CI 0.75 to 1.10), exercise-based CR may result in a large reduction in cardiovascular mortality (RR 0.58, 95% CI 0.43 to 0.78; 8 trials) and MI (RR 0.67, 95% CI 0.50 to 0.90; 10 trials). Evidence is uncertain for CABG (RR 0.66, 95% CI 0.34 to 1.27; 4 trials), and PCI (RR 0.76, 95% CI 0.48 to 1.20; 3 trials). Meta-regression showed benefits in outcomes were independent of CHD case mix, type of CR, exercise dose, follow-up length, publication year, CR setting, study location, sample size or risk of bias. There was evidence that exercise-based CR may slightly increase HRQoL across several subscales (SF-36 mental component, physical functioning, physical performance, general health, vitality, social functioning and mental health scores) up to 12 months' follow-up; however, these may not be clinically important differences. The eight trial-based economic evaluation studies showed exercise-based CR to be a potentially cost-effective use of resources in terms of gain in quality-adjusted life years (QALYs).

AUTHORS' CONCLUSIONS

This updated Cochrane Review supports the conclusions of the previous version, that exercise-based CR provides important benefits to people with CHD, including reduced risk of MI, a likely small reduction in all-cause mortality, and a large reduction in all-cause hospitalisation, along with associated healthcare costs, and improved HRQoL up to 12 months' follow-up. Over longer-term follow-up, benefits may include reductions in cardiovascular mortality and MI. In the last decade, trials were more likely to include females, and be undertaken in LMICs, increasing the generalisability of findings. Well-designed, adequately-reported RCTs of CR in people with CHD more representative of usual clinical practice are still needed. Trials should explicitly report clinical outcomes, including mortality and hospital admissions, and include validated HRQoL outcome measures, especially over longer-term follow-up, and assess costs and cost-effectiveness.

Novel cardiovascular biomarkers in patients with cardiovascular diseases undergoing intensive physical exercise

BACKGROUND

In this trial, we analyzed the plasma levels of novel biomarkers that reflect different pathophysiological pathways (sST2: mechanical strain, IGF-BP2: metabolic pathways, suPAR and GDF-15: inflammatory processes) in patients undergoing physical exercise to investigate the effects of training on their plasma concentrations.

METHODS

Plasma concentrations of novel biomarkers (sST2, IGF-BP2, suPAR and GDF-15) were analyzed by means of ELISA in patients with stable coronary artery disease (CAD) undergoing four weeks of high- and moderate-intensity training (EXCITE Trial) and in patients with one or more cardiovascular risk factors undergoing eight months of intensive physical exercise (IGF-BP2). Plasma levels of sST2 in patients undergoing eight months of intensive exercise have been published previously by our study group (1.13-fold change, P=0.045).

RESULTS

Four weeks of high-intensity exercise training resulted in a statistically significant change in the plasma level of sST2 (1.106-fold change, P=0.0054) and IGF-BP2 (1.24-fold-change, P=0.0165). Eight months of intensive exercise resulted in a significant increase of IGF-BP2 (median 61.2 ng/mL to 80.7 ng/mL, 1.319-fold change, P=0.006).

CONCLUSIONS

The significant increase of sST2 after four weeks might be a short-term effect due to the mechanical strain caused by the high-intensity training program, whereas the increase in IGF-BP2 after four weeks and eight months is likely a result of metabolic changes due to physical exercise.

Coronary Collateral Growth Induced by Physical Exercise: Results of the Impact of Intensive Exercise Training on Coronary Collateral Circulation in Patients With Stable Coronary Artery Disease (EXCITE) Trial

BACKGROUND

A well-developed coronary collateral circulation provides a potential source of blood supply in coronary artery disease. However, the prognostic importance and functional relevance of coronary collaterals is controversial with the association between exercise training and collateral growth still unclear.

METHODS AND RESULTS

This prospective, open-label study randomly assigned 60 patients with significant coronary artery disease (fractional flow reserve ≤0.75) to high-intensity exercise (group A, 20 patients) or moderate-intensity exercise (group B, 20 patients) for 4 weeks or to a control group (group C, 20 patients). The primary end point was the change of the coronary collateral flow index (CFI) after 4 weeks. Analysis was based on the intention to treat. After 4 weeks, baseline CFI increased significantly by 39.4% in group A (from 0.142±0.07 at beginning to 0.198±0.09 at 4 weeks) in comparison with 41.3% in group B (from 0.143±0.06 to 0.202±0.09), whereas CFI in the control group remained unchanged (0.7%, from 0.149±0.09 to 0.150±0.08). High-intensity exercise did not lead to a greater CFI than moderate-intensity training. After 4 weeks, exercise capacity, Vo2 peak and ischemic threshold increased significantly in group A and group B in comparison with group C with no difference between group A and group B.

CONCLUSIONS

A significant improvement in CFI was demonstrated in response to moderate- and high-intensity exercise performed for 10 hours per week.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01209637.

Endothelial fluid shear stress sensing in vascular health and disease

Endothelial cells transduce the frictional force from blood flow (fluid shear stress) into biochemical signals that regulate gene expression and cell behavior via specialized mechanisms and pathways. These pathways shape the vascular system during development and during postnatal and adult life to optimize flow to tissues. The same pathways also contribute to atherosclerosis and vascular malformations. This Review covers recent advances in basic mechanisms of flow signaling and the involvement of these mechanisms in vascular physiology, remodeling, and these diseases. We propose that flow sensing pathways that govern normal morphogenesis can contribute to disease under pathological conditions or can be altered to induce disease. Viewing atherosclerosis and vascular malformations as instances of pathological morphogenesis provides a unifying perspective that may aid in developing new therapies.

Exercise-based cardiac rehabilitation for coronary heart disease

BACKGROUND

Coronary heart disease (CHD) is the single most common cause of death globally. However, with falling CHD mortality rates, an increasing number of people live with CHD and may need support to manage their symptoms and prognosis. Exercise-based cardiac rehabilitation (CR) aims to improve the health and outcomes of people with CHD. This is an update of a Cochrane systematic review previously published in 2011.

OBJECTIVES

To assess the effectiveness and cost-effectiveness of exercise-based CR (exercise training alone or in combination with psychosocial or educational interventions) compared with usual care on mortality, morbidity and HRQL in patients with CHD.To explore the potential study level predictors of the effectiveness of exercise-based CR in patients with CHD.

SEARCH METHODS

We updated searches from the previous Cochrane review, by searching Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 6, 2014) from December 2009 to July 2014. We also searched MEDLINE (Ovid), EMBASE (Ovid), CINAHL (EBSCO) and Science Citation Index Expanded (December 2009 to July 2014).

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of exercise-based interventions with at least six months' follow-up, compared with a no exercise control. The study population comprised men and women of all ages who have had a myocardial infarction (MI), coronary artery bypass graft (CABG) or percutaneous coronary intervention (PCI), or who have angina pectoris, or coronary artery disease. We included RCTs that reported at least one of the following outcomes: mortality, MI, revascularisations, hospitalisations, health-related quality of life (HRQL), or costs.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all identified references for inclusion based on the above inclusion and exclusion criteria. One author extracted data from the included trials and assessed their risk of bias; a second review author checked data. We stratified meta-analysis by the duration of follow up of trials, i.e. short-term: 6 to 12 months, medium-term: 13 to 36 months, and long-term: > 3 years.

MAIN RESULTS

This review included 63 trials which randomised 14,486 people with CHD. This latest update identified 16 new trials (3872 participants). The population included predominantly post-MI and post-revascularisation patients and the mean age of patients within the trials ranged from 47.5 to 71.0 years. Women accounted for fewer than 15% of the patients recruited. Overall trial reporting was poor, although there was evidence of an improvement in quality of reporting in more recent trials.As we found no significant difference in the impact of exercise-based CR on clinical outcomes across follow-up, we focused on reporting findings pooled across all trials at their longest follow-up (median 12 months). Exercise-based CR reduced cardiovascular mortality compared with no exercise control (27 trials; risk ratio (RR) 0.74, 95% CI 0.64 to 0.86). There was no reduction in total mortality with CR (47 trials, RR 0.96, 95% CI 0.88 to 1.04). The overall risk of hospital admissions was reduced with CR (15 trials; RR 0.82, 95% CI 0.70 to 0.96) but there was no significant impact on the risk of MI (36 trials; RR 0.90, 95% CI 0.79 to 1.04), CABG (29 trials; RR 0.96, 95% CI 0.80 to 1.16) or PCI (18 trials; RR 0.85, 95% CI 0.70 to 1.04).There was little evidence of statistical heterogeneity across trials for all event outcomes, and there was evidence of small study bias for MI and hospitalisation, but no other outcome. Predictors of clinical outcomes were examined across the longest follow-up of studies using univariate meta-regression. Results show that benefits in outcomes were independent of participants' CHD case mix (proportion of patients with MI), type of CR (exercise only vs comprehensive rehabilitation) dose of exercise, length of follow-up, trial publication date, setting (centre vs home-based), study location (continent), sample size or risk of bias.Given the heterogeneity in outcome measures and reporting methods, meta-analysis was not undertaken for HRQL. In five out of 20 trials reporting HRQL using validated measures, there was evidence of significant improvement in most or all of the sub-scales with exercise-based CR compared to control at follow-up. Four trial-based economic evaluation studies indicated exercise-based CR to be a potentially cost-effective use of resources in terms of gain in quality-adjusted life years.The quality of the evidence for outcomes reported in the review was rated using the GRADE method. The quality of the evidence varied widely by outcome and ranged from low to moderate.

AUTHORS' CONCLUSIONS

This updated Cochrane review supports the conclusions of the previous version of this review that, compared with no exercise control, exercise-based CR reduces the risk of cardiovascular mortality but not total mortality. We saw a significant reduction in the risk of hospitalisation with CR but not in the risk of MI or revascularisation. We identified further evidence supporting improved HRQL with exercise-based CR. More recent trials were more likely to be well reported and include older and female patients. However, the population studied in this review still consists predominantly of lower risk individuals following MI or revascularisation. Further well conducted RCTs are needed to assess the impact of exercise-based CR in higher risk CHD groups and also those presenting with stable angina. These trials should include validated HRQL outcome measures, explicitly report clinical event outcomes including mortality and hospital admissions, and assess costs and cost-effectiveness.

Prognostic value of VEGF in patients submitted to percutaneous coronary intervention

We examined the longitudinal changes of VEGF levels after percutaneous coronary intervention for predicting major adverse cardiac events (MACE) in coronary artery disease (CAD) patients. VEGF was measured in 94 CAD patients' serum before revascularization, 1-month and 1-year after. Independently of clinical presentation, patients had lower VEGF concentration than a cohort of healthy subjects (median, IQ: 15.9, 9.0–264 pg/mL versus 419, 212–758 pg/mL; P < 0.001) at baseline. VEGF increased to 1-month (median, IQ: 276, 167–498 pg/mL; P < 0.001) and remained steady to 1-year (median, IQ: 320, 173–497 pg/mL; P < 0.001) approaching control levels. Drug eluting stent apposition and previous medication intake produced a less steep VEGF evolution after intervention (P < 0.05). Baseline VEGF concentration <40.8 pg/mL conveyed increased risk for MACE in a 5-year follow-up. Results reflect a positive role of VEGF in recovery and support its importance in CAD prognosis.

Cardiac rehabilitation and outcome in stable outpatients with recent myocardial infarction

OBJECTIVE

To compare the mortality rate and the rate of subsequent ischemic events (myocardial infarction [MI], ischemic stroke, or limb amputation) in patients with recent MI according to the use of cardiac rehabilitation or no rehabilitation.

DESIGN

Longitudinal observational study.

SETTING

Ongoing registry of outpatients.

PARTICIPANTS

Patients (N=1043) with recent acute MI were recruited; of these, 521 (50%) participated in cardiac rehabilitation.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Subsequent ischemic events and mortality rates were registered.

RESULTS

Over a mean follow-up of 18 months, 50 patients (4.8%) died and 49 (4.7%) developed 52 subsequent ischemic events (MI: n=43, ischemic stroke: n=6, limb amputation: n=3). Both the mortality rate (.16 vs 5.57 deaths per 100 patient-years; rate ratio=.03; 95% confidence interval [CI], 0.0-0.1]) and the rate of subsequent ischemic events (1.65 vs 4.54 events per 100 patient-years; rate ratio=0.4; 95% CI, 0.2-0.7) were significantly lower in cardiac rehabilitation participants than in nonparticipants. Multivariate analysis confirmed that patients in cardiac rehabilitation had a significantly lower risk of death (hazard ratio=.08; 95% CI, .01-.63; P=.016) and a nonsignificant lower risk of subsequent ischemic events (hazard ratio=.65; 95% CI, .30-1.42).

CONCLUSIONS

The use of cardiac rehabilitation in patients with recent MI was independently associated with a significant decrease in the mortality rate and a nonsignificant decrease in the rate of subsequent ischemic events.