Predictors of improvements in exercise capacity during cardiac rehabilitation in the recovery phase after coronary artery bypass graft surgery versus acute myocardial infarction

Effect of in-patient cardiac rehabilitation at rehabilitation hospital for cardiology patients: two-center trial

The effectiveness of cardiac rehabilitation (CR) in patients with cardiovascular disease requiring continuous CR from an acute care hospital to a convalescent rehabilitation hospital is unknown. Therefore, we compared the effect of CR in a rehabilitation hospital for patients with cardiovascular disease with that of those who underwent cardiovascular surgery. Sixty-nine consecutive patients were admitted to two rehabilitation hospitals for CR. Patients were classified by primary disease into two groups: patients with cardiovascular disease (cardiology group, 26 patients) and patients who underwent cardiovascular surgery (surgery group, 43 patients). Clinical information, physical function, cognitive function, activities of daily living (ADL), quality of life (QOL), amount of CR, and length of hospital stay were compared between the two groups. Compared with clinical features, age was significantly higher in the cardiology group (P < 0.001), and the preadmission Barthel index was significantly lower in the cardiology group (P = 0.025). Physical function at the time of transfer was significantly lower in the cardiology group than in the surgery group for the short physical performance battery (P < 0.001), gait speed (P = 0.005), and 6-min walking distance (P = 0.042). No significant difference was found in the amount of CR performed or the length of hospital stay, and no interaction effects were observed in improvements in physical function, exercise tolerance, or QOL. In conclusion, in rehabilitation hospitals, patients with cardiovascular disease were older, had lower preadmission ADL, and had lower a physical function at transfer than those who underwent cardiovascular surgery, but CR improved physical function and QOL to the same extent. The results suggest that the recovery of patients with cardiovascular disease may be similar to those who undergo cardiovascular surgery.

Heartbeat tracking task performance, an indicator of interoceptive accuracy, is associated with improvement of exercise tolerance in patients undergoing home-based cardiac rehabilitation

Aims

Interoception is the sensing function of physiological conditions and is crucial in self-regulation and decision-making. We examined the association of heartbeat tracking task performance, an indicator of interoceptive accuracy, with the degree of improvement in exercise tolerance in patients undergoing home-based cardiac rehabilitation.

Methods and results

Participants underwent baseline peak oxygen uptake (VO₂) measurements and a heartbeat tracking task. The heartbeat tracking task score varies between 0 and 1, with higher scores indicating a better heartbeat perception. After 6 months of home-based exercise training, peak VO₂ was measured again, and the percentage change (%Δ peak VO₂) relative to the peak VO₂ at baseline was calculated. Univariate regression analysis was performed to examine the association between %Δ peak VO₂ and the heartbeat tracking task score. Multiple regression analysis was performed to determine the predictors of %Δ peak VO₂. Of 120 participants, 100 patients (age 65.9 ± 11.9 years; 86% male) were included. There was a significant positive association between %Δ peak VO₂ and the heartbeat tracking task score at baseline (R ² = 0.236, P < 0.001). In multiple regression analysis, the percentage of measured peak VO₂ to the predicted value (%predicted peak VO₂) (β = -0.248, P = 0.002), exercise adherence (β = 0.364, P < 0.001), and heartbeat tracking task score at baseline (β = 0.372, P < 0.001) were significantly associated with %Δ peak VO₂.

Conclusions

Heartbeat tracking task performance, an indicator of interoceptive accuracy, at baseline is associated with the degree of improvement in exercise tolerance.

Determinants of Functional Improvement After Cardiac Rehabilitation in Acute Coronary Syndrome

Introduction

Cardiac rehabilitation (CR) is an effective tool for secondary prevention after acute coronary syndrome (ACS).

Aim

Aim of our study was to find the significant determinants of exercise capacity (evaluated with the six-minute walking test—6-MWT) and functional improvement in patients undergoing CR after an ACS.

Methods

The study group included 298 patients (mean age 61.6 ± 10.2 years; males 80.2%) who, after ACS, were enrolled in CR program at Niguarda Hospital in Milan from 2015 to 2018. For all patients, we collected anamnestic, clinical and instrumental cardiological data. All patients performed a 6-MWT at the beginning (6-MWT-1) and at the end (6-MWT-2) of CR program. Δ meters were used to represent functional improvement.

Results

Multiple linear regression models were carried out for 6-MWT-1, 6-MWT-2, Δ meters and % Δ meters. Standardized regression coefficients showed that age (β = − 0.237; p < 0.001), BMI (β = − 0.116; p = 0.006) and heart rate (β = − 0.082; p = 0.040) were determinants of exercise capacity (6MWT-1 and 2), whereas age (β = −.231; p = 0.004), sex (β = − 0.187; p = 0.008) and BMI (β = − 0.164; p = 0.022) were determinants of functional improvement (Δ meters).

Conclusions

Our data showed that functional improvement after CR in ACS patients is mainly related to non-cardiological variables. Instead it is related to intrinsic factors, both modifiable (BMI) and non-modifiable (age, sex).

Supplementary Information

The online version contains supplementary material available at 10.1007/s40292-021-00473-7.

Changes and prognostic value of cardiopulmonary exercise testing parameters in elderly patients undergoing cardiac rehabilitation: The EU-CaRE observational study

Objective

We aimed 1) to test the applicability of the previously suggested prognostic value of CPET to elderly cardiac rehabilitation patients and 2) to explore the underlying mechanism of the greater improvement in exercise capacity (peak oxygen consumption, VO₂) after CR in surgical compared to non-surgical cardiac patients.

Methods

Elderly patients (≥65 years) commencing CR after coronary artery bypass grafting, surgical valve replacement (surgery-group), percutaneous coronary intervention, percutaneous valve replacement or without revascularisation (non-surgery group) were included in the prospective multi-center EU-CaRE study. CPETs were performed at start of CR, end of CR and 1-year-follow-up. Logistic models and receiver operating characteristics were used to determine prognostic values of CPET parameters for major adverse cardiac events (MACE). Linear models were performed for change in peak VO₂ (start to follow-up) and parameters accounting for the difference between surgery and non-surgery patients were sought.

Results

1421 out of 1633 EU-CaRE patients performed a valid CPET at start of CR (age 73±5.4, 81% male). No CPET parameter further improved the receiver operation characteristics significantly beyond the model with only clinical parameters. The higher improvement in peak VO₂ (25% vs. 7%) in the surgical group disappeared when adjusted for changes in peak tidal volume and haemoglobin.

Conclusion

CPET did not improve the prediction of MACE in elderly CR patients. The higher improvement of exercise capacity in surgery patients was mainly driven by restoration of haemoglobin levels and improvement in respiratory function after sternotomy.

Trial registration

Netherlands Trial Register, Trial NL5166.

Improvements in exercise tolerance with an exercise intensity above the anaerobic threshold in patients with acute myocardial infarction

Anaerobic threshold (AT) from cardiopulmonary exercise tests (CPX) is the standard for measuring exercise intensity among patients with cardiovascular disease in Japan. However, it remains controversial whether AT represents the safety limit for exercise intensity in patients with cardiovascular disease. The purpose of this study was to investigate cardiac rehabilitation (CR) efficacy and safety with exercise intensities above the AT and at a traditional AT in a randomized trial. The participants included 57 patients who were admitted to the outpatient CR unit with a diagnosis of acute myocardial infarction. The participants were randomly divided as follows: 25 patients in the AT group, who performed aerobic exercises with an intensity at the AT; and 32 patients in the "Over AT" group, who performed exercises at an intensity higher than the AT. The following components were measured: maximum oxygen uptake (peak VO₂), oxygen uptake at the AT (AT VO₂), increase in oxygen uptake during exercise (ΔVO₂/ΔWR) during the CPX, vascular endothelial function test (%FMD: the percentage of flow-mediated dilation), and isometric knee extension strength. The measurements were obtained at the start of the exercise therapy and after 2, 3, and 4 months. They were compared within and between groups, and the correlation between the rates of improvement was investigated. Peak VO₂, AT VO₂, ΔVO₂/ΔWR, and %FMD had significantly improved after 3 months in both groups. The isometric knee extension strength had improved in the "Over AT" group after 2 months. Interactions were observed with peak VO₂, ΔVO₂/ΔWR, and isometric knee extension strength. However, %FMD was not significantly different between the groups. In the "Over AT" group, the rate of improvement in peak VO₂ was positively correlated with the improvement in the isometric knee extension strength (r = 0.61, p < 0.001), but not with %FMD. These data suggest that exercise at an intensity above the AT improved exercise tolerance faster than that at the AT, and this improvement rate was associated with changes in isometric knee extension strength.

Cardiac rehabilitation program improves exercise capacity in heart transplantation recipients regardless of marginal donor factors

Cardiac rehabilitation (CR) is recommended to improve exercise capacity after heart transplantation (HTx); however, the effects of marginal donor factors are unclear. Forty-one recipients participated in a 3-month CR program early after HTx (mean age 39 ± 14 years; 88% male). Patients were divided into marginal (≥ 2 marginal donor factors; n = 24) and control groups (< 2 marginal donor factors; n = 17). We examined donor and recipient factors related to change in peak oxygen uptake (peak VO₂) during the CR program using multiple linear regression analysis. Baseline characteristics were similar between groups, although the mean age was higher in the marginal group (43 ± 13 vs. 34 ± 14 years, p = 0.043). Peak VO₂ and knee extensor muscular strength (KEMS) improved significantly in both groups (p < 0.05), but there were no observed inter-group differences. Multiple analysis revealed change in KEMS (β = 0.52, 95% CI = 0.023-1.01) as an independent predictor of change in peak VO₂ after adjustment for recipients' age, sex, and CR attendance frequency (adjusted R² = 0.25, p = 0.0084), whereas marginal donor factors were not a predictor (p = 0.76). The CR program improved exercise capacity in HTx recipients regardless of marginal donor factors, suggesting that recipients of marginal donor hearts should be referred to CR programs.

Shorter Wait Times to Cardiac Rehabilitation Associated With Greater Exercise Capacity Improvements: A MULTISITE STUDY

PURPOSE

Comprehensive exercise-based cardiac rehabilitation (CR) results in improved, though highly variable, exercise capacity outcomes. Whether modifiable factors such as CR program wait time and session duration are associated with exercise capacity outcomes has not been adequately investigated.

METHODS

Patients with coronary heart disease (±primary and elective percutaneous coronary interventions, cardiac surgery) who participated in CR programs involved in a three-state audit (n = 32 sites) were eligible. Exercise capacity was measured using the 6-min walk test before and after a 6- to 12-wk supervised exercise program. CR program characteristics were also recorded (wait time, number of sessions). Correlations and linear mixed-effects models were used to identify associations between sociodemographic and CR program characteristics and change in exercise capacity.

RESULTS

Patients (n = 894) had a mean age of 65.9 ± 11.8 yr, 71% were males, 33% were referred for cardiac surgery, and median wait time was 16 d (interquartile range 9, 26). Exercise capacity improved significantly and clinically (mean increase 70.4 ± 61.8 m). After adjusting for statistically significant factors including younger age (<50 vs ≥80 yr [β = 52.07]), female sex (β = -15.86), exercise capacity at CR entry (β = 0.22) and those nonsignificant (ethnicity, risk factors, and number of sessions), shorter wait time was associated with greater exercise capacity improvement (β = 0.23).

CONCLUSIONS

This study confirms that greater exercise capacity improvements occur with shorter wait times. Coordinators should prioritize implementing strategies to shorten wait time to optimize the benefits of CR.

Efficacy of Cardiac Rehabilitation in Heart Failure Patients With Low Body Mass Index

BACKGROUND

Low body mass index (BMI) is a relevant prognostic factor for heart failure (HF), but HF patients with low BMI are reported to be at risk of not receiving optimal drug treatment. We sought to evaluate the efficacy of cardiac rehabilitation (CR) in patients with low vs. normal BMI. Methods and Results: We studied 152 consecutive patients (low BMI, n=32; normal BMI, n=119) who participated in a 3-month CR program. Low BMI was defined as <18.5 kg/m²and normal BMI, as 18.5≤BMI<25 kg/m². All patients underwent cardiopulmonary exercise testing and muscle strength testing at the beginning and end of the 3-month CR program. After CR, a significantly greater proportion of HF patients with low BMI had a positive change in peak V̇O₂than in the normal BMI group (91% vs. 70%; P=0.010). Average percent change in peak V̇O₂was significantly greater in patients with low vs. normal BMI (17.1±2.8% vs. 7.8±1.5%; P<0.001). In addition, on multivariable logistic regression, low BMI was an independent predictor of a positive change in peak V̇O₂after CR (OR, 3.97; 95% CI: 1.10-14.31; P=0.035).

CONCLUSIONS

CR has a greater effect in patients with low than normal BMI, and low BMI is an independent predictor of a positive change in peak V̇O₂. Thus, CR should be strongly recommended for HF patients with low BMI.