Efficacy of out-patient cardiac rehabilitation in low prognostic risk patients after acute myocardial infarction in primary intervention era

Background: The efficacy of out-patient cardiac rehabilitation (OPCR) in patients with a low prognostic risk after acute myocardial infarction (AMI) is unclear in the recent primary intervention era. Methods and Results: A total of 637 AMI patients who participated in in-hospital cardiac rehabilitation were divided into 2 groups; low prognostic risk group (n=219; age <65 years, successful reperfusion, Killip class I, peak serum creatine kinase <6,000 U/L, and left ventricular ejection fraction ≥40%) and non-low prognostic risk group (n=418). The prevalence of coronary risk factors (CRF) was compared between the 2 groups. Then, in the lowrisk group, the efficacy of OPCR was compared between active OPCR participants (n=52; ≥20 sessions/3 months) and non-active participants (n=60; <6 sessions/3 months). Compared with the non-low prognostic risk group, the low prognostic risk group had a significantly higher prevalence of current smokers (72% vs. 49%, P<0.05) and patients with multiple CRF (3 or more; 49% vs. 39%, P<0.05). Among the low-risk group, active OPCR participants showed a significantly greater improvement in exercise capacity (peak VO₂, P<0.05) and maintained a better CRF profile (total cholesterol, triglyceride and blood pressure, all P<0.05) than inactive participants at 3 months. Conclusions: Low prognostic risk AMI patients have a higher prevalence of multiple CRF than non-low risk patients. Even in this low risk group, active participation in OPCR is associated with improved exercise capacity and better CRF profile.