Predictors of atrial fibrillation after coronary artery bypass surgery

ABSTRACT

In order to determine the predictors of atrial fibrillation [A F] after coronary artery bypass surgery [CABG], 99 patients who were scheduled for CABG were studied [age ranged from 35 to 75 years, mean of 53.9 +/- 9.57 years]. The patients were subjected to a careful history analysis and a thorough clinical examination. A resting electrocardiogram and an echocardiogram as well as complete rigt and left coronary angiography and left ventriculography were performed for every patient. CABG surgery was performed using standard echniques. Patients were monitored for the occurrence of AF by continuous electrocardiographic telemetry for the first postoperative week. Sustained AF was defined as an episode lasting more than thirty minutes. The relation of AF to several perioperative variables was studied. Preoperative variables included age, gender, presence of diabetes mellitus, hypertension, chronic obstructive pulmonary disease, preoperative medications [digoxin, beta blockers and calcium channel blockers], right coronary artery stenosis, left ventricular ejection fraction and preoperative serum magnesium level. lntraoperative variables included aortic cross-clamp time, cardiopulmonary bypass time and number of distal anastomosis. Postoperative variables included peak postoperative MB fraction of creatine kinase level [CKMB] and serum magnesium level and beta blocker therapy. Stepwise logistic regression analysis [odds ratio +/- 95% CI, P value] was performed to detemnine which of these variables were independent predictors of A F. Sixteen patients out of the 99 developed AF [16.2%]. It was found that the following variables are independent predictors of Af Advancing age [OR = 1.7/10 years; CI, 0.86 to 3.4; P = 0.07], hypertension [OR = 2; CI, 1.05 to 3.8; P = 0.01] and cardiopulmonary bypass time [OR = 1.02; CI, 1 to1.04; P = 0.05]. All the other studied variables were not found to be independent predictors of AF. Advancing age, previous hostory of systemic hypertension, and longer cardiopulmonary bypass time were found to he important independent predictors of AF following CABG. There was a trend towards lower postoperative serum magnesium level in patients with AF although this did not reach statistical significance. Other variables as gender, diabetes mellitus, chronic obstructive pulmonary disease, right coronary artery stenosis, left ventricular ejection fraction, preoperative serum magensium level, aortic cross-clamp time, number of distal anastomosis, postoperative peak CKMB and beta blocker therapy were found not to be important predictors of postoperative AF in CABG patients