Effect of Exercise Based Cardiac Rehabilitation on Cardiorespiratory Fitness in Adults with Congenital Heart Disease

Background: The purpose of this study was to investigate whether patients with adult congenital heart disease (ACHD) benefit from exercise-based cardiac rehabilitation (CR) short- and long-term with regard to improvement of cardiorespiratory fitness. Methods: Cardiopulmonary exercise tests (CPET) completed by ACHD patients between January 2000 and October 2019 were analysed retrospectively. Linear mixed models were performed for peak oxygen consumption (VO2) with patients as random effect and age, sex, disease classification, preceding surgery (<= 3 months) and preceding CR (<= 4 weeks for short term and >4 weeks for long term) as fixed effects. Results: 1056 CPETs of 311 ACHD patients with simple (7), moderate (188) or great (116) complexity heart defects were analysed. The 59 patients who completed a CR (median age 27 yrs, 38% females) increased peak VO2 from before to after CR by a median of 2.7 (IQR -0.6 to 5.5) ml/kg/min. However, in the multivariate mixed model, peak VO2 was non-significantly increased short-term after CR (beta 0.8, 95%CI -0.7 to 2.4), not maintained long-term after CR (beta 0.0, 95%CI -1.7 to 1.6) but significantly reduced after surgery (beta -5.1, 95%CI -7.1 to -3.1). The 20 CR patients after surgery increased their peak VO2 by 6.2 (IQR 3.6-9.5) ml/kg/min, while the 39 CR patients without preceding surgery increased it by 0.9 (IQR -1.5 to 3.1) ml/kg/min. Conclusions: The increase in peak VO2 with CR was mainly due to recovery from surgical intervention. The small independent benefit from CR was not maintained long-term, highlighting the potential to improve current CR concepts in ACHD populations.