Left Atrial Volume and Post-Operative Atrial Fibrillation after Aortic Valve Replacement

Post-operative atrial fibrillation (POAF) after valve surgery is associated with increased morbidity and mortality. Risk factors identified in the past to predict POAF are of moderate accuracy. We performed a retrospective analysis of 139 patients undergoing aortic valve replacement for aortic stenosis. Post-operative AF occurred in 44% of the patients. In multivariate analysis only left atrial volume (LAV) index was a predictor of POAF. A LAV index of >46 cc/m2 predicted POAF with a sensitivity and specificity of 92% and 77%. We propose that LAV index can be used preoperatively to identify patients at risk for POAF to target preventive interventions. Background: Post-operative atrial fibrillation (POAF) is common after valve surgery and is associated with increased morbidity and mortality. Many of the previously identified predictors of POAF are of moderate accuracy. Left atrial volume (LAV) index has been proposed in the past as a predictor of POAF in patients undergoing cardiac surgery. In patients with aortic stenosis (AS), increased LAV is a marker of severity of stenosis. Hypothesis: Left atrial volume index is a very good predictor of POAF in patients undergoing aortic valve replacement (AVR) for AS. Methods: We performed a retrospective analysis of 139 consecutive patients with no previous atrial fibrillation (AF) undergoing AVR for AS in our center. Results: Post-operative AF occurred in 44% of patients. Patients with POAF had a longer hospital stay compared to patients without (12 vs 8 days; p < 0.001). In univariate analysis, age (p = 0.046), aortic valve area (p = 0.005) and LAV index (p < 0.001) were significant predictors of POAF. In multivariate analysis only LAV index (R2= 0.58; p < 0.001) predicted POAF. A LAV index > 46ml/m2 predicted POAF with a sensitivity and specificity of 92% and 77% respectively. Moreover, there was a significant increase in the incidence of POAF with increasing quartiles of LAV index, supporting causality. Conclusion: Left atrial volume index is an excellent predictor of POAF in patients undergoing AVR for AS. It can be used for selecting patients who are at a high risk for developing POAF to target preventive interventions.