Association Between Exercise Capacity and Health-Related Quality of Life During and After Cardiac Rehabilitation in Acute Coronary Syndrome Patients: A Substudy of the OPTICARE Randomized Controlled Trial

Abstract

Objective: To examine the strength of the association between exercise capacity and health-related quality of life (HRQOL) during and after cardiac rehabilitation (CR) in patients with acute coronary syndrome (ACS) who completed CR.

Design: Prospective cohort study.

Setting: Outpatient CR center.

Participants: Patients (N=607) with ACS who completed CR.

Interventions: Multidisciplinary 12-week exercise-based CR program.

Main outcome measures: At baseline (pre-CR), the 6-Minute Walk Test (6MWT) was performed to determine exercise capacity, and the MacNew Heart Disease Health-related Quality of Life questionnaire was used to assess HRQOL. Measurements were repeated immediately after completion of CR (post-CR): at 12 months and 18 months follow-up. Multivariable linear regression, including an interaction term for time and exercise capacity, was applied to study the association between exercise capacity and HRQOL at different time points relative to CR, whereas model parameters were estimated by methods that accounted for dependency of repeated observations within individuals.

Results: Mean age in years ± SD was 58±8.9 and 82% of participants were male. Baseline mean 6MWT distance in meters ± SD was 563±77 and median (25th-75th percentile) global HRQOL was 5.5 (4.6-6.1) points. Mean 6MWT distance (P<.001) and the global (P<.001), physical (P<.001), emotional (P<.001) and social (P<.001) domains of HRQOL improved significantly during CR and continued to improve during follow-up post-CR. Independent of the timing relative to CR (ie, pre-CR, post-CR, or during follow-up), a difference of 10 m 6MWT distance was associated with a mean difference in the global HRQOL domain of 0.007 (95% confidence interval [CI], 0.001-0.014) points (P=.029) and a mean difference in the physical domain of 0.009 (95% CI, 0.001-0.017) points (P=.023).

Conclusions: Better exercise capacity was significantly associated with higher scores on the global and physical domains of HRQOL, irrespective of the timing relative to CR, albeit these associations were weak. Hence, CR programs in secondary prevention should continue to aim at enhancing both HRQOL and exercise capacity.

Trial registration: ClinicalTrials.gov NCT01395095.

Keywords: Acute coronary syndrome; Cardiac rehabilitation; Health-related quality of life; Rehabilitation; Walk test.