Determinants of the effects of physical training and of the complications requiring resuscitation during exercise in patients with cardiovascular disease

Background Benefits of cardiac rehabilitation with exercise therapy are well-established, although individual reactions are heterogeneous. The identification of determinants of training effects is useful from a prognostic point of view, but data regarding this are scarce. Furthermore, limited data exist on the determinants of complications during exercise in cardiac patients. This study aimed to investigate the determinants (1) of training effects in cardiac rehabilitation and (2) of complications requiring resuscitation during exercise activities at the hospital and during continued exercise at a sports club for cardiac patients. Design Clinical association study. Methods Determinants of changes in peak oxygen uptake (VO2) after 3 months of cardiac rehabilitation were determined by multiple regression analysis (n=1909). Determinants of events requiring resuscitation (n=21) were assessed by logistic regression analysis. Results Improvements in peak VO2 and exercise duration averaged 26%. Eighteen per cent of the variance in absolute improvements of peak VO2 was explained, with age and training characteristics as the strongest determinants. Twenty-one per cent of the variation in relative improvements was explained, with baseline exercise performance and training characteristics being the strongest determinants. The intake of anti-arrhythmics (odds ratio=5.5; P<0.001) and the presence of ST-segment depression ( >= 1 mm) at baseline exercise testing (odds ratio=1.6; P<0.001) were predictive for serious complications. The occurrence of events requiring resuscitation was higher at the sports club (1/16 533 versus 1/29 214 patient-hours). Conclusions Age, baseline exercise performance and training characteristics were predictive for training effects in cardiac rehabilitation. Anti-arrhythmics and ST-segment depression at baseline exercise testing were predictive for complications.