Abstract 10122: Left Atrial Mechanical Function Predicts Risk of Atrial Fibrillation After Cardiac Surgery
Background: Postoperative atrial fibrillation (POAF) is an important and frequent complication of cardiac surgery. Left atrial (LA) enlargement has been reported to be a risk factor for POAF, but the relationship between LA mechanics and POAF is not well understood. We examined the relationship between preoperative LA function and POAF in patients with no prior history of atrial fibrillation.
Methods: 101 subjects underwent preoperative transthoracic echocardiograms and were followed for occurrence of POAF during the hospitalization. LA maximum (LAVmax) and minimum (LAVmin) volumes were measured (area-length method) and indexed to body surface area (LAVmaxI, LAVminI, respectively). LA total emptying fraction (TEF) was calculated as ((LAVmax - LAVmin) / LAVmax) × 100%). Univariate and multivariate analyses examined clinical and echocardiographic predictors of POAF.
Results: POAF occurred in 41% of subjects. Mean age was 64 ± 13 years, mean left ventricular ejection fraction was 48 ± 15%, mean LA TEF was 49 ± 15%, mean LAVmaxI was 38 ± 15 mL/m2, and mean LAVminI was 20 ± 13 mL/m2. Age, history of heart failure, LAVmaxI, LAVminI, LA TEF, and mitral E/E' were univariate predictors of POAF. Mean LA TEF was 43 ± 15% in patients with POAF and 55 ± 13% in those without POAF (p<0.001). On multivariate logistic regression analysis, age, LA TEF and LAVminI were significant predictors of POAF. The discriminatory power (c index) of previously established cutpoints of LA TEF<50%, LAVmaxI>32 ml/m2, and LAVminI>13 ml/m2 for POAF was examined (see Table). After adjusting for age, the model incorporating LA TEF<50% continued to have the highest point estimate of discriminatory power, which was statistically significant compared to LAVmaxI>32 ml/m2 (P=0.0426).
Conclusions: LA TEF is an independent predictor of POAF and is a stronger predictor of POAF than maximal LA volume. Impaired LA mechanical function may help to identify patients who are most likely to benefit from prophylaxis for POAF.
- © 2010 by American Heart Association, Inc.