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.

Keywords: atrial fibrillation; coronary artery bypass grafting; risk factors.