Association of atrial nicotinamide adenine dinucleotide phosphate oxidase activity with the development of atrial fibrillation after cardiac surgery.

OBJECTIVES

Our goal was to evaluate the role of myocardial nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity and plasma markers of oxidative stress in the pathogenesis of post-operative atrial fibrillation (AF).

BACKGROUND

Atrial fibrillation is a common complication of cardiac surgery, leading to increased morbidity and prolonged hospitalization. Experimental evidence suggests that oxidative stress may be involved in the pathogenesis of AF; however, the relevance of this putative mechanism in patients undergoing cardiac surgery is unclear.

METHODS

We measured basal and NADPH-stimulated superoxide production in right atrial appendage samples from 170 consecutive patients undergoing conventional coronary artery bypass surgery. Plasma markers of lipid and protein oxidation (thiorbabituric acid-reactive substances, 8-isoprostane, and protein carbonyls) were also measured in blood samples drawn from a central line before surgery and after reperfusion.

RESULTS

Patients who developed AF after surgery (42%) were older and had a significantly increased atrial NADPH oxidase activity than patients who remained in sinus rhythm (SR) (in relative light units/s/mug protein: 4.78 +/- 1.44 vs. 3.53 +/- 1.04 in SR patients, p < 0.0001). Plasma markers of lipid and protein oxidation increased significantly after reperfusion; however, neither pre-operative nor post-operative measurements differed between patients who developed AF and those who remained in SR after surgery. Multivariate analysis identified atrial NADPH oxidase activity as the strongest independent predictor of post-operative AF (odds ratio 2.41; 95% confidence interval 1.71 to 3.40, p < 0.0001).

CONCLUSIONS

Atrial NADPH oxidase activity is independently associated with an increased risk of post-operative AF, suggesting that this oxidase system may be a key mediator of atrial oxidative stress leading to the development of AF after cardiac surgery.