Atrial fibrillation (AF) has been reported to occur in up to 20-40% of patients undergoing coronary artery bypass grafting (CABG). Postoperative AF plays a major role in the determination of hemodynamic deterioration and can be associated with thromboembolic stroke. Aside from the risk factors of age, pain, cardiac dysfunction and hypokalemia, hypoxemia is also considered to be the major contributor to AF initiation and persistence. Aiming to the common postoperative complications, noninvasive positive pressure ventilation (NIV) provides an available modality to improve the oxygen and even obviate the reintubation.