The authors reported two cases of severe arrhythmia after gastrectomy in the patients with history of coronary bypass grafting (CABG) using the right gastroepiploic artery. The first patient was a 64-year-old man who had undergone CABG involving bypassing between the right coronary artery and the right gastroepiploic artery 5 months before. Partial gastrectomy was performed without significant complications. However, he showed severe bradycardia and low output status with anuria in the intensive care unit (ICU). The second patient was a 74-year-old man who had undergone CABG with the identical method 7 years before receiving partial gastrectomy. Although, surgery was performed with intraaortic balloon pumping for his mild heart failure, no other complication was observed during operation and ICU stay. Immediately after being moved to the ward on postoperative day 3, recurrent ventricular tachycardia occurred. Finally, the patient was implanted with an automatic defibrillator.