Background and Significance: In the United States approximately 220,000 patients undergo cardiac surgery per annum. Among potential complications, the incidence of atrial fibrillation (AF) is estimated at 30 - 60 %, and therefore presents the most common adverse event after cardiac surgery. Multiple complications may be associated with AF: Patients are usually subject to an increased length-of-stay in the intensive care unit and in the hospital. Furthermore, the risk for stroke and development of long-term AF is elevated, while further anticoagulation is required putting the patient at risk for bleeding. On average, an additional $10,000 - $20,000 is spent for each patient with AF. However, the exact burden of postoperative AF still remains unknown. Specific Aims of Research Project: 1. To collect data from an electrocardiogram (EKG) monitoring patch, we aim to accurately determine the prevalence of atrial fibrillation in patients undergoing cardiac surgery at our center. 2. To collect data on epidemiological characteristics to investigate risk factors for developing perioperative atrial fibrillation in patients undergoing cardiac surgery. This will allow us to create robust risk prediction models.