4

Abstract

Learning Objectives: Incidence of new onset postoperative atrial fibrillation (POAF) ranges from 9-20% of non-cardiac major thoracic and vascular surgeries and is associated with worse postoperative outcomes. A CHADS2 score of ≥ 2 has previously been associated with new onset POAF in cardiac surgery patients. The objective of the present study was to determine whether CHADS2 score alone and in the context of other clinical risk factors would be predictive of new onset POAF in non-cardiac major thoracic and vascular surgical patients. Methods: After IRB approval, 1,566 patients undergoing major non-cardiac thoracic and vascular surgery without known atrial fibrillation from 2006 through 2013 who were admitted to a surgical intensive care unit postoperatively were retrospectively identified. Baseline CHADS2 and clinical variables including daily fluid balance, electrolyte values, intra-and postoperative vasopressor and inotrope requirements, operation length, blood transfusion, and resumption of home cardiac medications were collected. The primary endpoint was correlation of CHADS2 with incidence of POAF. A multivariable Cox proportional hazards model was used to assess association between risk factors and POAF. Results: Two hundred twenty-one (14.1%) patients developed POAF at a median of 55 hours (IQR 30-93.7) after surgery. On univariate analysis, CHADS2 was significantly associated with POAF (HR 1.22 [95% CI 1.08-1.37] for every unit increase in score). This association persisted after multivariate adjustment (HR 1.17 [95% CI 1.04-1.31]). Intraoperative fluid administration (HR 1.03 [95% CI 1.01-1.06] per 1000 ml), preoperative beta blocker use (HR 2.04 [95% CI 1.44-2.90]), calcium channel blocker use (HR 0.67 [95% CI 0.49-0.93])and postoperative day 1 SOFA score (HR 1.08 [95% CI 1.03-1.12] for every unit increase in score) were also significantly associated. Model R2 was 0.76. Conclusions: CHADS2, when used in combination with baseline and clinical variables, is predictive of new POAF after major thoracic or vascular surgery and maybe useful in identifying at risk patients.