Changes in Aerobic Capacity Over Time in Elderly Patients With Acute Myocardial Infarction During Cardiac Rehabilitation

OBJECTIVE: To test the hypothesis that a longer duration of phase II cardiac rehabilitation is required to recover the exercise capacity of elderly patients compared to younger patients. METHODS: We retrospectively reviewed and analyzed the medical records of patients who were referred to our cardiac rehabilitation (CR) center and underwent percutaneous coronary intervention for acute myocardial infarction (AMI). A total of 70 patients were enrolled who underwent an exercise tolerance test (ETT) 3 weeks after the occurrence of an AMI (T0), 6 weeks after the first ETT (T1), and 12 weeks after the first ETT (T2). Patients older than 65 years were assigned to the elderly group (n=24) and those aged 65 years and younger to the younger group (n=46). Both groups performed center-based or home-based CR for 12 weeks (3 times per week and 1 session per day). Exercise intensity for each individual was based on the target heart rate calculated by the Karvonen formula. The change in maximal metabolic equivalents (MET(max)) of the two groups was measured at each assessment point (T0, T1, and T2) to investigate the recovery of exercise capacity. RESULTS: The younger group showed improvement in MET(max) between T0 and T1. However, MET(max) of the elderly group showed no significant improvement between T0 and T1. The exercise capacity, measured with MET(max), of all groups showed improvement between T0 and T2. CONCLUSION: Elderly patients with AMI need a longer duration of CR (>6 weeks) than younger patients with AMI.