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Abstract

Background: Atrial fibrillation (AF) is a frequent and serious postoperative complication in patients undergoing mitral valve replacement (MVR), especially in those with underlying mitral stenosis (MS). Postoperative AF increases the risk of morbidity, prolongs hospital stays, and is associated with elevated mortality. Early identification of risk factors is crucial for optimizing patient outcomes. Objective: To assess the incidence of postoperative atrial fibrillation in patients undergoing MVR for mitral stenosis and evaluate its association with clinical characteristics and outcomes. Study Design: Observational study. Setting: Cardiac Surgery Department of National Institute of Cardiovascular Diseases, Karachi, Pakistan. Duration of Study: January 2024 to January 2025. Methods: A total of 60 patients aged 18–70 years undergoing mitral valve replacement (MVR) for moderate to severe mitral stenosis were enrolled. Postoperative atrial fibrillation (AF) was identified through continuous electrocardiogram (ECG) monitoring during hospitalization. Data were collected on age, sex, comorbidities (diabetes mellitus and hypertension), prior mitral valve replacement (MVR), left atrial diameter, and left ventricular ejection fraction (LVEF). Postoperative outcomes included length of hospital stay, renal failure, and mortality. Statistical analysis was performed using chi-square and independent t-tests. A p-value < 0.05 was considered statistically significant. Results: Postoperative AF developed in 10 out of 60 patients (16.7%). Patients who developed AF were more likely to be over 50 years of age (90% vs. 48%, p = 0.01), have diabetes (80% vs. 18%, p < 0.0001), hypertension (80% vs. 22%, p < 0.0001), and a history of prior MVR (50% vs. 12%, p = 0.005). Left atrial enlargement (≥40 mm) and reduced LVEF (<50%) were significantly more common in the AF group (80% vs. 30%, p = 0.003; and 90% vs. 28%, p < 0.0001, respectively). Postoperative AF was significantly associated with extended hospital stay (>7 days: 80% vs. 22%, p < 0.0001), and increased mortality (70% vs. 2%, p < 0.0001). Conclusion: Postoperative atrial fibrillation is a common complication following MVR for mitral stenosis, with an incidence of 16.7%. It is significantly associated with advanced age, diabetes, hypertension, prior valve surgery, left atrial enlargement, and reduced LVEF. Its occurrence leads to worse clinical outcomes hospital stays and higher mortality. These findings underscore the need for careful preoperative risk assessment and targeted perioperative management strategies to mitigate the incidence and impact of postoperative AF.