Inflammation has been shown to be implicated in the pathophysiology of atrial fibrillation (AF). Interleukin-6 (IL-6) is a pleiotropic cytokine, functions as a mediator of inflammatory response and has both pro-inflammatory and anti-inflammatory properties. Little is known about genetic factors of inflammation in the accompanying atrial electrical remodeling expressed by P wave dispersion (Pdisp). The aim of the present study is to evaluate the association of -634C/G polymorphism of IL-6 gene with Pdisp in Han Chinese hypertensive patients with AF. A total of 100 patients with essential hypertension (EH) were eligible for this study. Patients with paroxysmal AF (n=50) were allocated to the AF group, and 50 subjects without AF to the control group. The PCR-based restriction fragment length polymorphism (PCR-RFLP) technique was used to assess the genotypes frequencies. The distribution of the IL-6 -634C/G genotypes (CC, CG, and GG) was 68.00%, 28.00%, and 4.00% in the controls, and 44.00%, 40.00%, and 16.00% in AF subjects, respectively (P=0.0269). The frequency of the G allele in the AF group was significantly higher than that in the control group (36.00% vs 18.00%, P=0.0041). Compared to the wild type CC, the G allele carriers (CG + GG genotypes) had a 2.7045-fold increased risk of AF (odds ratio =2.7045, 95% confidence interval =1.1966-6.1126, P=0.0156). AF patients with the CG + GG genotype had longer Pdisp (P=0.0032) than did patients with the CC genotype. The longer Pdisp in the subjects with the CG + GG genotype was also found in the control group (P=0.0016). These findings support that IL-6 -634C/G polymorphism is associated with Pdisp and AF, suggesting an active implication of inflammation in the atrial electrophysiological remodeling predisposing to AF.
Keywords: Atrial fibrillation; Chinese; P wave dispersion; essential hypertension; genetic polymorphism; interleukin-6.