Research article

Dose dependent effect of statins on postoperative atrial fibrillation after cardiac surgery among patients treated with beta blockers

Salima Mithani^1,2 , Muhammad S Akbar^1,2 , Deborah J Johnson³ , Michael Kuskowski⁶ , Katherine K Apple⁵ , Jana Bonawitz-Conlin⁵ , Herbert B Ward⁵ , Rosemary F Kelly⁵ , Edward O McFalls^3,4 , Hanna E Bloomfield⁷ , Jian-Ming Li^3,4 and Selcuk Adabag^3,4,7

¹  Department of Internal Medicine, Veterans Affairs Medical Center, Veterans Drive, Minneapolis 55417, USA

²  Department of Medicine, University of Minnesota, Delaware St SE, Minneapolis 55455, USA

³  Division of Cardiology, Veterans Affairs Medical Center, Veterans Drive, Minneapolis 55417, USA

⁴  Division of Cardiology, University of Minnesota, Delaware St SE, Minneapolis 55455, USA

⁵  Division of Cardiovascular Surgery, Veterans Affairs Medical Center, Veterans Drive, Minneapolis 55417, USA

⁶  Geriatric Research Education Center, Veterans Affairs Medical Center, Veterans Drive, Minneapolis 55417, USA

⁷  Center for Chronic Disease Outcomes Research, Veterans Affairs Medical Center, Veterans Drive, Minneapolis 55417, USA

author email corresponding author email

Journal of Cardiothoracic Surgery 2009, 4:61doi:10.1186/1749-8090-4-61

Published:	4 November 2009

Abstract

Background

Previous studies on the effects of Statins in preventing atrial fibrillation (AF) after cardiac surgery have shown conflicting results. Whether statins prevent AF in patients treated with postoperative beta blockers and whether the statin-effect is dose related are unknown.

Methods

We retrospectively studied 1936 consecutive patients who underwent coronary artery bypass graft (CABG) (n = 1493) or valve surgery (n = 443) at the Minneapolis Veterans Affairs Medical Center. All patients were in sinus rhythm before the surgery. Postoperative beta blockers were administered routinely (92% within 24 hours postoperatively).

Results

Mean age was 66+10 years and 68% of the patients were taking Statins. Postoperative AF occurred in 588 (30%) patients and led to longer length of stay in the intensive care unit versus those without AF (5.1+7.6 days versus 2.5+2.3 days, p < 0.0001). Patients with a past history of AF had a 5 times higher risk of postoperative AF (odds ratio 5.1; 95% confidence interval 3.4 to 7.7; p < 0.0001). AF occurred in 31% of patients taking statins versus 29% of the others (p = 0.49). In multivariable analysis, statins were not associated with AF (odds ratio (OR) 0.93, 95% confidence interval (CI) 0.7 to 1.2; p = 0.59). However, in a subgroup analysis, the patients treated with Simvastatin >20 mg daily had a 36% reduction in the risk of postoperative AF (OR 0.64, 95% CI 0.43 to 0.6; p = 0.03) in comparison to those taking lower dosages.

Conclusion

Among cardiac surgery patients treated with postoperative beta blockers Statin treatment reduces the incidence of postoperative AF when used at higher dosages