Background: Cardiac rehabilitation (CR) has been shown to improve exercise intolerance and QoL, and minimize re-hospitalizations in patients with congestive heart failure (CHF). However, studies on early CR in patients with acute myocardial infarction (AMI) who developed CHF following percutaneous coronary intervention (PCI) are rare. The purpose of this study is to evaluate the effectiveness of early CR on patients with CHF after AMI following PCI.Methods: Two hundred thirty-seven patients who developed heart failure after AMI following PCI were enrolled. Patients were divided into heart failure with reduced ejection fraction (HFrEF) group and heart failure with mid-range ejection fraction (HFmrEF) group. Of which, 78 patients who accepted a two-week CR were further divided into two subgroups based on major adverse cardiovascular events (MACE). Key cardio-pulmonary exercise testing (CPX) variables that may affect the prognosis were identified through the comparison of the cardio-respiratory fitness (CRF).Results: Early CR significantly reduced cardiac death in patients with HFrEF, and reduced re-hospitalization in patients with HFmrEF after AMI (P <0.01). Serum potassium and CR ratio were independent risk factors for MACE in patients with both HFrEF and HFmrEF after AMI. In the CR group who developed MACE, there were more diabetics (P=0.035), with higher serum potassium (P=0.043), and lower PETCO2 at VT (P=0.016). PETCO2 at VT was an independent risk factor for re-hospitalization. The incidence of re-hospitalization was significantly lower when the PETCO2 at VT was greater than 33.5mmHg (P=0.03).Conclusions: Early CR reduced the incidence of MACE in patients with heart failure after AMI following PCI. The PETCO2 at VT is an independent risk factor for re-hospitalization, and could be used as a key evaluating hallmark for early CR in patients who developed heart failure after AMI.