Intracardiac and extracardiac markers of inflammation during atrial fibrillation

Abstract

BACKGROUND A decrease in inflammation after cure of atrial arrhythmias suggests that such arrhythmias are pro-inflammatory, and lower inflammatory marker levels in the coronary sinus suggest that atrial arrhythmias result in the intracardiac appropriation of inflammatory cytokines. OBJECTIVE To investigate the effect of atrial fibrillation on inflammatory markers drawn from intra and extracardiac chambers. METHODS We performed a case control study of 167 AF patients and 207 controls. Blood from intra and extracardiac sites was obtained from a subset of patients undergoing curative AF ablation (n=46). RESULTS There were no significant differences in C-Reactive Protein (CRP) or interleukin-6 (IL-6) between those with and without a history of AF. Both were significantly higher when blood was drawn during AF compared to in sinus rhythm: median CRP 3.1 mg/dL (interquartile range [IQR] 1.0–6.0) versus 1.7 mg/dL (IQR 0.7 – 3.9, p=0.0005); median IL-6 2.3 ng/ml (IQR 1.5–3.9) versus 1.5 ng/ml (IQR 0.7–2.5; p=0.007). This finding persisted after adjusting for potential confounders. AF ablation patients in AF exhibited a positive median left atrial minus coronary sinus (LA-CS gradient) CRP (0.3 mg/dL , IQR −0.03–1.1), whereas those in sinus rhythm had a negative median LA-CS gradient CRP (−0.2, IQR −0.8-[−0.02], p=0.01); femoral artery minus femoral vein gradients in AF versus sinus rhythm failed to show any differences. CONCLUSIONS AF at the time of the blood draw, rather than a history of AF, was independently associated with inflammation. Differences in trans-cardiac gradients suggest that AF results in sequestration of inflammatory cytokines in the heart.