Predictors of post-operative atrial fibrillation in patients undergoing isolated coronary artery bypass grafting

Abstract

Background: Post-operative atrial fibrillation (POAF) is the most common cardiac arrhythmia occurring after coronary artery bypass grafting (CABG). Arrhythmia leads to prolonged hospitalisation and may have an impact on both short-term and long-term prognoses. Aim: The aim of this paper was to evaluate the incidence of POAF in patients after CABG as well as to identify its predictors. Methods: The study was performed on 791 patients (selected from a group of 1031 patients who underwent CABG in the Clinical Department of Cardiology in the years 2009–2011) who did not suffer from atrial fibrillation (AF) prior to isolated CABG. Data on co-existing diseases, as well as data collected at the time of surgery and in the post-operative period, were evaluated. Results: The average age of patients in the examined group was 64.6 ± 9.1 years. Emergency CABG was performed on 38% of patients, whereas 75.1% of patients underwent CABG with the use of extracorporeal circulation. Based on the incidence of POAF, the post-CABG patients were classified into a POAF(+) group that comprised 166 (21%) patients, and a POAF(–) group involving 625 (79%) patients. The first occurrence of arrhythmia during the first three days after surgery was observed in 76.5% of patients. The average age of POAF(+) and POAF(–) patients was 68.7 ± 8.8 years and 63.5 ± 8.9 years, respectively (p < 0.0001). The respective incidence rates of co-existing diseases in patients with POAF and those without POAF were as follows: arterial hypertension, 80.1% vs. 75.8% (p = 0.29); heart failure, 18.7% vs. 21.1% (p = 0.56); type 2 diabetes, 24.1% vs. 26.2% (p = 0.64). Stable angina pectoris was diagnosed in 22.3% of patients with POAF and 15% of patients without POAF (p = 0.034). The following conditions were more frequently observed in patients with POAF compared with those without POAF: low cardiac output syndrome, 28.9% vs. 14.2% (p < 0.0001) and cardiac tamponade, 9% vs. 4.6% (p = 0.044), respectively. Red blood cell transfusions were performed more often in patients with POAF compared to those without POAF (70.5% vs. 55.7%, respectively, p = 0.0008). Multivariate analysis revealed the following potential predictors of POAF: age ≥ 70 years (HR 2.3), preoperative stable angina pectoris (HR 1.7), and post-CABG low cardiac output syndrome (HR 1.8). Conclusions: POAF was diagnosed in 21% of post-CABG patients, and the major predictors were: age ≥ 70 years, preoperative stable angina, as well as low cardiac output syndrome following CABG.