The study aims to evaluate and compare the incidence of atrial arrhythmias (including Post-Operative Atrial Fibrillation (POAF), atrial flutter, and atrial tachycardia) stratified by baseline Utah fibrosis stages and overall fibrosis (%) of the left atrial wall area. The investigators hypothesize that patients with a higher baseline Utah fibrosis staging will experience a higher incidence of POAF. The study also aims to evaluate and compare the in-hospital mortality, length-of-stay (LOS), complication rates (strokes, pneumonia, respiratory failure etc.) of the different Utah fibrosis stage cohorts. Perform cost analysis and compare between patients with POAF and patients without POAF. The investigators hypothesize that patients experiencing POAF will have a higher mortality rate, longer LOS, greater complications, and therefore, additional hospital costs.