Patients with myocardial infarction related potential malignant ventricular arrhythmia have high risk of sudden death. The aim of this clinical trial is evaluating therapeutic efficacy of unipolar or bipolar radiofrequency ablation in Coronary Artery Bypass Grafts (CABG) Surgery, which can reduce myocardial ischemia and block reentry circuits of ventricular arrhythmia at the same time. The observation indexes include the morbidity of potential malignant ventricular arrhythmia and major adverse cardiovascular events in mid-long-term after CABG surgery.