Baseline Atrial Fibrosis Predicts Risk for Post-operative Atrial Fibrillation in Patients Undergoing Cardiac Surgery

Inclusion Criteria: * Male or female patients age 40 years of age or older * Patients with no history of atrial arrhythmia (atrial fibrillation, atrial flutter, atrial tachycardia) scheduled to undergo cardiac surgery (These surgeries include but are not limited to coronary artery bypass graft (CABG), valvular repair/reconstruction, aneurysm repair, and insertion of pacemaker). Exclusion Criteria: * Patients with a history of atrial arrhythmia (atrial fibrillation, atrial flutter, atrial tachycardia) * Patients with a history of cardiac or open chest surgery * Patients with a history of catheter ablation * Patients under the age of 40 * Patients with left ventricular assist device (LVAD) or scheduled to have LVAD implanted * Patients who have previously undergone extracorporeal membrane oxygenation (ECMO) * Patients who have undergone or will undergo heart transplantation * Patients with any health related Late Gadolinium Enhancement (LGE)-MRI contraindications (including previous allergic reaction to gadolinium, pacemakers, defibrillators, other devices/implants contraindicated for MRI) * Acute or chronic severe renal disease with a low glomerular filtration rate (GFR), \<30 mL per minute per 1.73 m2 will be excluded from the trial. (A creatinine measurement should be available within the last 6 months. If not, a creatinine blood test will be drawn to assess for renal function before the MRI acquisition). * Patients weighing \> 300 lbs. (MRI image quality decreases due to increased body mass index) * Patients currently pregnant or breastfeeding, or plan to become pregnant during the study period * Patients with cognitive impairment preventing them from giving informed consent will be excluded from the study * Patients who cannot read, speak, and/or understand English