Postoperative Atrial Fibrillation Decreased Long-term Survival Rate in Isolated Valve Surgery

Background: Postoperative Atrial Fibrillation (POAF) is the most common complication of open cardiac surgery related to prognosis and morbidity.However, it is controversial whether POAF is associated with excess mortality independent of associated risk factors after cardiac surgery.Methods and results: POAF was identified in 425 patients (34.5%) of 1229 patients underwent isolated valve repair and/or replacement operation.Patients have more chances to experience POAF if they were older than 65 years old (p < 0.0001), Caucasian (p=0.0017), with heart failure (NYHA Class >= III) (p<0.001), with hypertension (p<0.001) or with peripheral vascular diseases (p<0.001).The unadjusted fiveyear survival rate was 82.8% for patients without POAF and 71.3% for with POAF (p < 0.0001).An unadjusted hazard ratio for POAF was 1.85 (95% CI: 1.40 to 2.43).With a propensity score-matching model, in the 406 pairs of patients under adjusted survival analysis showed significant lower survival rate in POAF (p=0.001) with the adjusted hazard ratio of 1.40 (95% CI: 1.01 to 1.92), compared to without POAF.Conclusion: Our present study supported that POAF is independently associated with an increased long-term mortality in patients who had isolated valve surgery.All isolated valve surgery patients without history of atrial fibrillation between January 1997 and December 2007 in Texas Heart Institute Research Database (THIRD) were included for this study.This study was approved by the hospital Institutional Review Board.Data was abstracted with the key words of "valve repair", "valve replacement", and "atrial fibrillation".Postoperative atrial fibrillation was defined as patient who has a new onset of atrial fibrillation/flutter of any duration between operation and discharge with a diagnosis documented by physician.All cause of death was collected and followed for up to 5 years.Patients without feedback were excluded.All of variables were identified from database.The risk factors that are associated with POAF included: Age, Gender, Race, Hypertension, Congestive Heart Failure, Diseases of the heart valves, Acute or prior Myocardial Infarction (MI), Diabetes Mellitus, Peripheral Vascular Disease, Renal Failure; Pulmonary Disease, Cerebrovascular Disease, Endocarditis, Overweight, Smoking.Survival was measured as time (in years) to either death or last follow-up from date of surgery.All patients without follow-up data were excluded. Statistics analysisBaseline characteristics were reported as mean with standard deviation or as percentage of total patients in each group.Normally distributed continuous variables were compared using student t-test and Kruskal-Wallis test were utilized for continuous variables that were not normally distributed.Chi-square tests were performed for variables presented as percentages.Fitting a logistics regression model with POAF as the outcome variable and all the baseline variables in Table 1 as predictors, a propensity score matching model was developed to adjust the baseline characteristic differences between postoperative atrial fibrillation and non-postoperative atrial fibrillation groups.Logistic regression and Cox proportional hazards methods were employed to assess the unadjusted and adjusted hazard ratio of association between occurrences of postoperative AF and long-term survival rate.Survival was analyzed by constructing Kaplan-Meier curves.All statistical analyses were performed using