Sleep apnea is a prevalent disorder in patients with coronary artery disease. Previous studies suggested sleep apnea was associated with coronary plaque burden and future adverse cardiovascular events. Sleep apnea is also associated with a high incidence of atrial fibrillation in patients undergoing coronary artery bypass grafting. Yet, previous reports used Berlin Questionnaire and Epworth Sleepiness Scale Questionnaire to diagnose sleep apnea. However, these screening questionnaires are not as accurate as a proper sleep study. In the SABOT study, the investigators used the portable sleep device to diagnose sleep apnea, and evaluate the relationship between sleep apnea and cardiovascular outcomes after coronary artery bypass surgery.