Randomised controlled trial in women with coronary artery disease investigating the effects of aerobic interval training versus moderate intensity continuous exercise in cardiac rehabilitation: CAT versus MICE study

Abstract

Background: The primary aim of the present study was to investigate the effects of aerobic interval training (AIT) versus moderate intensity continuous exercise (MICE) on aerobic exercise capacity (V̇O2peak), in women only, with coronary artery disease (CAD) and who were referred to a large, 24-week outpatient cardiac rehabilitation (CR) programme. Secondary objectives included comparing the effects of AIT versus MICE on cognition, cardiovascular risk profile, adherence and quality of life before and after the 24-week CR programme.

Methods: Thirty-one postmenopausal women with CAD (left ventricular ejection fraction >35%; 68.2±9.2 years of age; V̇O2peak: 19.1±3.5 mL kg-1 min-1) were randomised to 24 weeks of usual care MICE (60%-80% of V̇O2peak, five times per week) or AIT (four 4-min intervals at 90%-95% of peak heart rate, three times per week+two times per week usual care MICE). Differences between and within groups were assessed using independent samples t-tests and paired samples t-tests, respectively. Treatment effect analysis of AIT on V̇O2peak and secondary outcomes was determined using analysis of covariance with baseline values as covariates.

Results: A randomised controlled trial study design was unfeasible in this female CAD population. Unanticipated challenges in recruitment availability and eligibility, in combination with a 59% and 50% attrition rate in the AIT and MICE group, respectively, rendered this study underpowered to detect differences between groups. The per protocol treatment effect analysis, however, unveiled a 0.95 mL kg-1 min-1 improvement in V̇O2peak in response to AIT over MICE (p<0.001).

Conclusions: Further research is necessary to elucidate the patient profile and circumstances under which the potential for the implementation of AIT may be individualised, and offered in clinical practice.

Trial registration: NCT02966158.

Keywords: aerobic exercise capacity; cardiac rehabilitation; coronary artery disease; interval training; women.

Conflict of interest statement

Competing interests: None declared.

© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

Figures

Figure 1

Flow chart of the process of study enrolment, randomisation and completion. BP, blood pressure; n, number of patients.

Figure 2

Individual plots demonstrating the variability in the change in aerobic exercise capacity (V̇O2peak) in patients randomised to performing either aerobic interval training (AIT) (n=7), or moderate intensity continuous exercise (MICE) (n=7). The thicker lines represent the mean values across time, with a significant difference observed between AIT and MICE groups (p=0.005). Four patients in the MICE group and one patient in the AIT group failed to attend their 12-week CPA. CPA, cardiopulmonary exercise assessment.