Background: The standard of treatment for treating individuals with severe left main stem and three-vessel coronary artery disease (CAD) is coronary artery bypass graft (CABG) surgery. Compared to medical care, it is linked to better survival. Objective: To compare the early effects of coronary artery bypass grafting on individuals with borderline vs decreased ejection fraction (EF).  Patients and methods: This is a prospective study that included 61 patients with CAD who were subjected for CABG. The included patients were divided into 2 groups; HF with border line EF (HFbEF) group included 29 patients with borderline ejection fraction and HF with reduced EF (HFrEF) group included 32 patients in reduced ejection fraction. All patients were operated upon in Zagazig University Hospitals, Egypt and followed up during the period from September 2018 till September 2021. Each patient underwent: full history taking, thorough clinical examination, laboratory investigations and echocardiographic assessment. Results: There was great improvement of EF in HFrEF group exceeding HFbEF group. The EF at 6 months post-operative EF was 40.5±9.5% versus 43.2±7.85% in the HFbEF group versus in the HFrEF group respectively (p=0.151). Among borderline EF group there was no significant difference regarding EF before and after coronary artery revascularization (P-value= 0.34). There was a statistically significant improvement post-CABG regarding New York Heart Association (NYHA) classification among HFbEF group and HFrEF (P-value = 0.00004 and <0.0001, respectively). Conclusion: There was great improvement of systolic left ventricular EF in reduced ejection fraction group exceeding borderline EF group.