Statin therapy may influence the incidence of postoperative atrial fibrillation: what is the evidence?

Abstract

Atrial fibrillation is the most common postoperative arrhythmia in patients who undergo cardiac surgery. We sought to determine whether the administration of statins reduces the incidence of postoperative atrial fibrillation in cardiac surgery patients. We performed a meta-analysis on all studies published between 2004 and 2008 that reported comparisons between statin treatment or nontreatment in these patients. Our primary focus was the incidence of postoperative atrial fibrillation. Random-effects modeling and sensitivity analysis were used to evaluate the consistency of the calculated treatment effect. Ten qualifying studies generated a total of 4,459 patients. The incidence of postoperative atrial fibrillation was 22.6% (622/2,758) in the statin-treated group and 29.8% (507/1,701) in the untreated group. Using the random-effects model, we calculated an odds ratio (OR) of 0.60 (95% confidence interval [CI], 0.48-0.76). When we considered only the 4 randomized studies (919 patients) in order to reduce the effects of heterogeneity, this significant reduction in the incidence of postoperative atrial fibrillation in the statin group was maintained (OR, 0.55; 95% CI, 0.41-0.73) with no heterogeneity (chi2 of heterogeneity, 2.96; P = 0.4). In studies wherein only coronary artery bypass grafting was performed, statin treatment decreased postoperative atrial fibrillation (OR, 0.64; 95% CI, 0.43-0.95). We conclude that statin administration results in a reduction in the incidence of atrial fibrillation in patients who undergo cardiac surgery. Further research into the underlying mechanism can elucidate possible relationships between the dosage and type of statin used.

Keywords: Atrial fibrillation/drug therapy/physiopathology/prevention & control; cardiac surgical procedures/complications; data interpretation, statistical; hydroxymethylglutaryl-CoA reductase inhibitors/therapeutic use; meta-analysis as topic; models, statistical; postoperative complications/drug therapy/epidemiology/prevention & control; randomized controlled trials as topic/methods; risk factors.

Fig. 1. Molecular effects of statins on the left atrium (adapted from Adam and colleagues, with permission). AT-1 = angiotensin-1; Gα = G protein, α subunit; GΓA = G protein, γ subunit; LA = left atrium; LV = left ventricle; NADPH = reduced form of nicotinamide-adenine dinucleotide phosphate; NO = nitrous oxide; RA = right atrium; RV = right ventricle

Fig. 2. Search approach and selection of the studies for the meta-analysis.

Fig. 3. Meta-analysis of the A) studies and B) randomized controlled trials that compared the incidence of postoperative atrial fibrillation in statin-treated patients versus patients who received no statin treatment. Squares indicate point estimates of treatment effect (odds ratio), the size of the squares represents the weight attributed to each study, and horizontal bars indicate the 95% confidence interval (CI). The diamond represents the summary OR from the pooled studies with 95% CI. P < 0.05 was considered statsitically significant. AF = atrial fibrillation; OR = odds ratio

Fig. 4. Funnel plot A) that identifies sources of heterogeneity, and B) after exclusion of an outlying study, resulting in heterogeneity. AF = atrial fibrillation; OR = odds ratio; SE = standard error