Dose-related effect of statins on atrial fibrillation after cardiac surgery

Background. Atrial fibrillation (AF) is the most common heart rhythm abnormality after cardiac surgery. It increases morbidity and prolongs hospital stay. A role for statins in the prevention of AF has been suggested. We hypothesized that the incidence of postoperative AF due to statin therapy is dose-related. Methods. A retrospective study of 680 consecutive patients undergoing coronary bypass graft surgery and/or aortic valve replacement was done. Excluded were 57 patients (8.4%) with history of AF, permanent pacemakers, and those receiving antiarrhythmic medication. Preoperative statin treatment and occurrence of postoperative AF were examined using propensity score matching to adjust for differences in patient characteristics between the statin and no-statin groups. Results. The cohort comprised 623 patients. The statin group had a 27.1% incidence of postoperative AF vs 38.3% in the no-statin group (adjusted odds ratio [OR], 2.00; 95% confidence interval, 1.24 to 3.24; p=0.004). Simvastatin (40 mg) and atorvastatin (40 mg) demonstrated the greatest effect on postoperative AF at 15.6% and 21.2%, respectively, vs no statins (respective adjusted ORs, 3.89 [p < 0.0001] and 2.76 [p=0.012]). Intermediatedose (20 mg) statins were also effective against AF, at 24.4% for simvastatin (adjusted OR, 2.32; p=0.004) and 26.4% for atorvastatin (adjusted OR, 1.99, p=0.047). Low-dose statins, simvastatin or atorvastatin (10 mg), did not influence postoperative AF. Conclusions. Statin treatment may reduce the incidence of AF after cardiac surgery. Higher-dose statins have the greatest preventative effect, whereas low-dose statins do not influence postoperative AF.