European Journal of Preventive Cardiology

We aimed to compare: (1) two different periodized aerobic training protocols (linear (LP) versus non-linear (NLP)) on the cardiopulmonary exercise response in patients with coronary heart disease; (2) the proportion of responders between both training protocols.

A randomized controlled trial.

A total of 39 coronary heart disease patients completed either LP (n = 20, 65 ± 10 years) or NLP (n = 19, 66 ± 5 years). All patients completed a cardiopulmonary exercise testing with gas exchange measurements. Patients underwent a 12-week supervised exercise program including an isoenergetic aerobic periodized training and a similar resistance training program, 3 times/week. Weekly energy expenditure was constantly increased in the LP group for the aerobic training, while it was deeply increased and intercepted with a recovery week each fourth week in the NLP group. Peak oxygen uptake (peak V̇O₂), oxygen uptake efficiency slope, ventilatory efficiency slope (V̇E/V̇CO₂ slope), V̇O₂ at the first (VT₁) and second (VT₂) ventilatory thresholds, and oxygen pulse (O₂ pulse) were measured. Responders were determined according the median value of the Δpeak V̇O₂ (mL.min⁻¹.kg⁻¹).

We found similar improvement for peak V̇O₂ (LP: +8.1%, NLP: +5.3%, interaction: p = 0.37; time: p < 0.001) and for oxygen uptake efficiency slope, VT₁, VT₂ and O₂ pulse in both groups (interaction: p > 0.05; time: p < 0.05) with a greater effect size in the LP group. The proportion of non-, low and high responders was similar between groups (p = 0.29).

In contrast to the athletes, more variation (NLP) does not seem necessary for greater cardiopulmonary adaptations in coronary heart disease patients.

Functional capacity is an important endpoint for therapies oriented to older adults with cardiovascular diseases. The literature on predictors of exercise capacity is sparse in the elderly population. In a longitudinal European study on effectiveness of cardiac rehabilitation of seven European countries in elderly (>65 years) coronary artery disease or valvular heart disease patients, predictors for baseline exercise capacity were determined, and reference ranges for elderly cardiac patients provided.

Mixed models were performed in 1282 patients (mean age 72.9 ± 5.4 years, 79% male) for peak oxygen consumption relative to weight (peak VO₂; ml/kg per min) with centre as random factor and patient anthropometric, demographic, social, psychological and nutritional parameters, as well as disease aetiology, procedure, comorbidities and cardiovascular risk factors as fixed factors.

The most important predictors for low peak VO₂ were coronary artery bypass grafting or valve surgery, low resting forced expiratory volume, reduced left ventricular ejection fraction, nephropathy and peripheral arterial disease. Each cumulative comorbidity or cardiovascular risk factors reduced exercise capacity by 1.7 ml/kg per min and 1.1 ml/kg per min, respectively. Males had a higher peak VO₂ per body mass but not per lean mass. Haemoglobin was significantly linked to peak VO₂ in both surgery and non-surgery patients.

Surgical procedures, cumulative comorbidities and cardiovascular risk factors were the factors with the strongest relation to reduced exercise capacity in the elderly. Expression of peak VO₂ per lean mass rather than body mass allows a more appropriate comparison between sexes. Haemoglobin is strongly related to peak VO₂ and should be considered in studies assessing exercise capacity, especially in studies on patients after cardiac surgery.

The European Cardiac Rehabilitation in the Elderly (EU-CaRE) HORIZON 2020 project compares the sustainable effects of cardiac rehabilitation (CR) in elderly patients.

A total of 1633 patients with coronary artery disease (CAD) or heart valve replacement (HVR), with or without revascularization, aged 65 or above, who participated in CR were included. Peak oxygen uptake (VO_2peak), smoking, body mass index, diet, physical activity, serum lipids, psychological distress and medication were assessed before and after CR (T0 and T1) and after 12 months (T2). Patients undergoing coronary artery bypass surgery or surgical HVR had lower VO_2peak at T0 and a greater increase to T1 and T2 (2.8 and 4.4 ml/kg/min, respectively) than CAD patients undergoing percutaneous or no revascularization (1.6 and 1.4 ml/kg/min, respectively). After multivariable adjustment, earlier CR uptake was associated with greater improvements in VO_2peak. The proportion of CAD patients with three or more uncontrolled risk factors declined from 58.4% at T0 to 40.1% at T2 (p < 0.0001). Psychological distress scores all improved and adherence to medication was overall good at all sites. There were significant differences in risk factor burden across sites, but no CR program was superior to others.

The outcomes of VO_2peak in CR programs across Europe seemed mainly determined by timing of uptake and were maintained or even further improved at 1-year follow-up. Despite significant improvements, 40.1% of CAD patients still had three or more risk factors not at target after 1 year. Differences across sites could not be ascribed to characteristics of the CR programs offered.

Heart failure with preserved ejection fraction (HFpEF) is a prevalent syndrome, with exercise intolerance being one of its hallmarks, contributing to worse quality of life and mortality. High-intensity interval training is an emerging training option, but its efficacy in HFpEF patients is still unknown.

Single-blinded randomized clinical trial.

Single-blinded randomized clinical trial with exercise training 3 days per week for 12 weeks. HFpEF patients were randomly assigned to high-intensity interval training or moderate continuous training. At baseline and after 12 week follow-up, patients underwent clinical assessment, echocardiography and cardiopulmonary exercise testing (CPET).

Mean age was 60 ± 9 years and 63% were women. Both groups (N = 19) showed improved peak oxygen consumption (VO₂), but high-intensity interval training patients (n = 10) had a significantly higher increase, of 22%, compared with 11% in the moderate continuous training (n = 9) individuals (3.5 (3.1 to 4.0) vs. 1.9 (1.2 to 2.5) mL·kg⁻¹·min⁻¹, p < 0.001). Ventilatory efficiency and other CPET measures, as well as quality of life score, increased equally in the two groups. Left ventricular diastolic function also improved with training, reflected by a significant reduction in E/e′ ratio by echocardiography (−2.6 (−4.3 to −1.0) vs. −2.2 (−3.6 to −0.9) for high-intensity interval training and moderate continuous training, respectively; p < 0.01). There were no exercise-related adverse events.

This randomized clinical trial provided evidence that high-intensity interval training is a potential exercise modality for HFpEF patients, being more effective than moderate continuous training in improving peak VO₂. However, the two strategies were equally effective in improving ventilatory efficiency and other CPET parameters, quality of life score and diastolic function after 3 months of training.

Cardiac rehabilitation plays a vital role in secondary prevention of cardiovascular patients. Female sex and higher age, however, are associated with non-referral to cardiac rehabilitation. Improving exercise capacity during cardiac rehabilitation is essential to reduce morbidity and mortality risks. The objective of this study was to closely examine the beneficial changes in exercise capacity of older patients of both sexes during cardiac rehabilitation and to identify the most important predictors of the change in exercise capacity.

A sample of 13,612 patients (mean age = 69.10 ± 11.8 years, 63.7% men, 19% > 80 years) was analysed. Data were prospectively assessed from 2012–2018 in six Swiss in-patient cardiovascular rehabilitation clinics. Improvement in exercise capacity measured with the six-minute walking test represents the outcome variable. Univariate and multivariate analyses, as well as the random forest method were used to estimate variable importance.

Mean improvement in the six-minute walking test was 113.5 ± 90.5 m (men = 118.7 ± 110.0; women = 104.4 ± 93.0, Cohen’s d = 0.16). The presence of heart failure, diabetes mellitus and psychiatric diagnoses was related to reduced but nonetheless clinically relevant six-minute walking test improvement. Random forest analysis suggests that baseline exercise capacity, age, time in rehabilitation and heart failure were the most important predictors for improvement in exercise capacity. Clinically relevant improvements in exercise capacity (>45 m) were also present into old age (85 years) and for both sexes.

As indicated by these results, efforts need to be increased to refer eligible patients to structured rehabilitation programmes, irrespective of patients’ age and sex.

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.

A systematic review and meta-analysis.

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.

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).

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.

Despite its role as an effective intervention to improve the long-term health of patients with cardiovascular disease and existence of national guidelines on timeliness, many health services still fail to offer cardiac rehabilitation in a timely manner after referral. The impact of this failure on patient health and the additional burden on healthcare providers in an English setting is quantified in this article.

Two logistic regressions are conducted, using the British Heart Foundation National Audit of Cardiac Rehabilitation dataset, to estimate the impact of delayed cardiac rehabilitation initiation on the level of uptake and completion. The results of these regressions are applied to a decision model to estimate the long-term implications of these factors on patient health and National Health Service expenditure.

We demonstrate that the failure of 43.6% of patients in England to start cardiac rehabilitation within the recommended timeframe results in a 15.3% reduction in uptake, and 7.4% in completion. These combine to cause an average lifetime loss of 0.08 years of life expectancy per person. Scaled up to an annual cohort this implies 10,753 patients not taking up cardiac rehabilitation due to the delay, equating to a loss of 3936 years of life expectancy. We estimate that an additional £12.3 million of National Health Service funding could be invested to alleviate the current delay.

The current delay in many patients starting cardiac rehabilitation is causing quantifiable and avoidable harm to their long-term health; policy and research must now look at both supply and demand solutions in tackling this issue.

Mobile health interventions, especially smartphone applications (apps), have been proposed as promising interventions for supporting adherence to healthy behaviour in patients post cardiac rehabilitation (CR). The overall aim of the study was to examine the effect of individualized follow-up with an app for one year on peak oxygen uptake (VO_2peak) in patients completing CR.

The study was designed as a single-blinded multicentre randomized controlled trial.

The intervention group (IG) received individualized follow-up enabled with an app for one year, while the control group (CG) received usual care. The primary outcome was difference in VO_2peak. Secondary outcomes included exercise performance (time to exhaustion, peak incline (%) and peak velocity (km/h)), bodyweight, resting blood pressure, lipid profile, triglycerides, exercise habits, health-related quality of life, health status and self-perceived goal achievement.

In total, 113 patients completing CR (73.4% with coronary artery disease, 16.8% after valve surgery and 9.8% with other heart diseases) were randomly allocated to the IG or CG. Intention to treat analyses showed a statistically significant difference in VO_2peak between the groups at follow-up of 2.2 ml/kg/min, 95% confidence interval 0.9–3.5 (p < 0.001). Statistically significant differences were also observed in exercise performance, exercise habits and in self-perceived goal achievement.

Individualized follow-up for one year with an app significantly improved VO_2peak, exercise performance and exercise habits, as well as self-perceived goal achievement, compared with a CG in patients post-CR. There were no statistically significant differences between the groups at follow-up in the other outcome measures evaluated.