Oxidative stress and inflammatory process in patients with atrial fibrillation: the role of left atrium distension.

BACKGROUND: Atrial fibrillation has been associated with increased oxidative stress, elevated inflammatory status and endothelial dysfunction. However, the underlying mechanisms regulating the expression of inflammatory markers or oxidative stress status are unclear. We searched for clinical determinants of oxidative stress status, endothelial function and inflammatory process in patients with chronic atrial fibrillation. METHODS: Sixty nine patients with chronic atrial fibrillation at a stable clinical state were recruited. Ejection fraction of the left ventricle and the dimensions of the left atrium were determined echocardiographically. Flow mediated dilatation (FMD) was evaluated in the brachial artery, while serum oxidized LDL (ox-LDL), matrix metalloproteinase-9 (MMP-9), soluble CD40-ligand (sCD40L) and C-reactive protein (CRP) were measured. RESULTS: FMD was correlated with CRP (r=-0.423, p=0.028), independently of other clinical parameters (beta(SE): -0.0039(0.00159), p=0.022). Ox-LDL was significantly correlated with left atrium diameter(r=0.358, p=0.005) independently of other clinical variables (beta(SE):1.288(0.455), p=0.007). The only independent predictors of MMP-9 were sCD40L (beta(SE):17.232(7.654), p=0.028), CRP (beta(SE):4.249(2.186), p=0.05) and gender (beta(SE):204.657(68.153), p=0.004), but not left atrium dimensions. Independent predictors of CRP were hypertension (beta(SE): 8.531(3.973), p=0.036), sCD40L (beta(SE): 0.779(0.408), p=0.06) and age (beta(SE): 0.381(0.201), p=0.063). CONCLUSIONS: There is a strong link between inflammation and endothelial function, in patients with atrial fibrillation. The maximum diameter of left atrium is the only independent predictor of oxidized LDL, suggesting that left atrium distension may predict oxidative stress status in these patients.