PREDICTING CARDIORESPIRATORY FITNESS IMPROVEMENT AT CARDIAC REHABILITATION COMPLETION: PATIENT FACTORS THAT DESERVE SPECIAL ATTENTION

Abstract

Cardiorespiratory fitness (CRF) has recently been proposed as a vital sign. Improvements in CRF achieved over the course of a cardiac rehabilitation (CR) program are strongly predictive of survival in patients with coronary artery disease (CAD). However, not all CR participants achieve equivalent gains in exercise capacity. Our objective was to determine predictors of post-CR CRF in a large, well described cohort of subjects completing CR. All subjects who completed the 12-week, comprehensive CR program at TotalCardiology-Rehabilitation between 1996 and 2016 were included. Baseline data including demographics, comorbidities, ejection fraction, and CAD severity were obtained from the program database and supplemented by The Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH) database. Subjects underwent a graded exercise test at program start and completion to determine peak metabolic equivalents (METs). A multivariable linear regression model with bootstrapping to refine estimates was developed to predict METs at program completion. A total of 10537 (1909 (18.1%) female; mean age 60.3 (SD 10.5) years) subjects had sufficient data for inclusion. Subjects had a high burden of comorbidities: 1993 (18.9%) had diabetes, 6406 (60.8%) had hypertension and 2343 (22.2%) were current smokers; nearly a fifth were over 70 years old (2026, 19.2%). Mean baseline METs achieved for the whole cohort was 7.6 (SD 2.0), this improved to 8.5 (SD 2.1) METs by 12 weeks. A multivariable regression model including baseline METs, sex, demographics, and co-morbidities was highly predictive of METs achieved at program completion (R2=0.8067; Table; figure). In particular, female sex, advanced age, current smoking status, South Asian ethnicity, and obesity were highly predictive of worse 12 week CRF. Expected CRF at the end of CR is highly predictable, with several key patient factors being clear determinants. While most identified patient factors are not modifiable, our analysis highlights populations that may require extra attention over the course of CR to attain maximal benefit.View Large Image Figure ViewerDownload Hi-res image Download (PPT)