Background Enlargement of the left atrium has been thoroughly studied in many clinical situations, especially its association with mortality and morbidity. Patients and Methods The study cohort included patients with rheumatic valve pathology such as stenosis and regurgitation. All patients underwent valvular surgical procedures including mitral valve replacement (MVR), aortic valve replacement (AVR), AVR with coronary artery bypass grafting (CABG), MVR with CABG, or AVR and MVR with or without CABG. This study included patients who underwent surgery between 2002 and 2017. Results Three hundred and forty-six patients were included in this study. The mean patient age was 51.6±16.1 years; 37% of the patients underwent AVR, 28% underwent MVR, and 13% underwent a combination of MVR with AVR, AVR with CABG in 6%, and MVR with CABG in 10%. The operative mortality rate was 5.8% (n=20). Univariate analysis revealed that the predictors of mortality included age (P < 0.001), body mass index (BMI) (P = 0.003), type of surgery performed (P = 0.007), hypertension (P = 0.005), emergent surgeries (P = 0.018), left atrial diameter (P = 0.003), cross-clamp time greater than 90 minutes (P = 0.007), postoperative acute kidney injury (AKI) (P = 0.044), postoperative stroke (P = 0.049), and surgical site infection (P = 0.047). Multivariate analysis revealed that predictors of mortality included age (P = 0.028, AOR=10.6), BMI (P = 0.003, AOR=3.12), re-exploration (P = 0.006, AOR=8.38), length of intensive care unit stay (P ≤ 0.002, AOR=4.55), and left atrial diameter (P = 0.003, AOR=10.64). Conclusion Enlargement of the left atrium has been studied extensively as a predictor of mortality and morbidity in different clinical situations, to the extent that some authors suggest adding it to risk stratification models. In this study, left atrial size >4 cm was found to strongly predict mortality after rheumatic heart valve surgery.