The impact of age and socioeconomic factors on response to exercise training in patients with ischemic heart disease, heart failure and after valve replacement
Authors: Rasmusen H.K , Mikkelsen N 
Published: November 2020

Abstract

The impact of baseline characteristics on response to exercise training in patients with ischemic heart disease.

Background
Exercise training improves peak oxygen uptake, an important predictor of mortality in patients with coronary artery disease (CAD). Unfortunately, some patients do not response with an increase in peak oxygen uptake after exercise training. If it is possible to identify these patients it would be possible to tailor their exercise training.

Purpose
To investigate if baseline characteristics can predict response to exercise training in patients with heart disease.

Methods
A retrospective analysis of 1443 CAD patients (age 64±11 y (mean (±SD)), 74% male, participated and completed an eight-week supervised outpatient exercise intervention with two weekly training sessions of 1.5 hours with high intensity interval- (&gt;80% of VO2peak) and resistance training. Patient characteristics were entered in the local database as the patients entered cardiac rehabilitation (CR). VO2peak was assessed before and after CR using a cardiopulmonary exercise test (CPET) with a maximal symptom limited bicycle ergometer test. Breathing gases were collected and analysed breath-by-breath. Each test aimed at physical exhaustion and a respiratory exchange ratio of more than 1.1 to ensure the validity of the CPET test. Patients were divided into responders defined as an improvement in aerobic capacity (change in VO2peak) after CR and non-responders if no improvement (change in VO2peak of 0.0ml/kg/min or less) post CR. We performed a multivariable logistic regression analysis using responders vs. non-responders as the endpoint. Explanatory variables were identified according to previous literature and comprised the following variables; age, sex, baseline VO2peak, tobacco use, diabetes, COPD, revascularization, working status, educational attainment, ethnicity and hypercholesteremia.

Results
1097 patients were responders and 346 (24%) non-responders to the exercise training despite no difference in attendance. Logistic regression analysis of responders vs. non-responders in relation to baseline characteristics are shown in the table.

Conclusion
In summarize, 24% of these heart patients were exercise non-responders. High baseline VO2peak, older age, having COPD, being on disability pension, low educational attainment and non-western ethnicity were predictors of training non-response. Identification of patients with a large likelihood of non-response is a beginning towards patient tailored exercise programmes.
Baseline characteristics in responders. CABG: coronary artery bypass graft; COPD: chronic obstructive pulmonary disease; PCI: percutaneous coronary intervention; SD: standard deviation; VO2peak: change in peak oxygen uptake. P-values of &lt;0.05 are considered significant and shown in bold. 95% confidence intervals are shown in last column.

Funding Acknowledgement
Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Helsefonden