β1-ADRENERGIC RECEPTOR POLYMORPHISMS AND RISK OF ATRIAL FIBRILLATION AFTER CARDIAC SURGERY IN IRANIAN POPULATION

Postoperative atrial fibrillation (POAF) is a frequent rhythm disturbance after cardiac surgery and is associated with poor cardiovascular outcomes. Beta-blocker therapy is an effective strategy to prevent or decrease the high incidence of POAF and β₁-adrenergic receptor (β₁AR) polymorphisms that affect the cardiac response to β₁AR antagonists. The study objective is to analyze the association between genetic variations in the β₁AR gene and the risk of POAF and the prophylactic effect of beta-blockers. Totally, 198 patients undergoing first-time cardiac surgery were examined. The patients after operation were grouped as either with POAF or without POAF according to their continuously electrocardiogram monitoring within ICU and hospital admission period. Subsequently, genotype frequencies of the β₁AR gene were determined by polymerase chain reaction-restriction fragment length polymorphism. The results showed that 63 patients (31.8%) of the total study population developed POAF. After the application of a multivariate logistic regression model, the incidence of POAF was associated with Arg389Gly genotype (OR=2.48; 95% CI, 1.06-5.76; p=0.036), Arg389Arg genotype (OR=3.38; 95% CI, 1.28-9.33; p=0.018) and Arg389Ser49 haplotype (OR=1.73; 95% CI, 1.07-2.80; p=0.027) in the whole population. In addition, subgroup analysis showed an association between Arg389Gly (OR=3.09; 95% CI, 1.12-8.52; p=0.03) and Arg389Arg (OR=4.72; 95% CI, 1.07-15.43; p=0.01) genotypes as well as Arg389Ser49 haplotype (OR=2.05; 95% CI, 1.16-3.62; p=0.013) with increased risk for POAF in patients using beta-blocker prophylaxis. These findings indicated that POAF might be related to the Arg389-β₁AR variant in the studied Iranian population, and this association appears to be more prominent among patients with beta-blocker prophylaxis.