Correlation of Plasma Adiponectin Levels and Adiponectin Gene Polymorphisms with Idiopathic Atrial Fibrillation

<b><i>Introduction:</i></b> Adiponectin is a cellular protein secreted by adipocytes, which is closely related to a variety of diseases, including atrial fibrillation (AF). Idiopathic atrial fibrillation (IAF) is defined as AF without hypertension, diabetes, and other underlying diseases. Genetic polymorphism of adiponectin affects serum adiponectin concentration. However, the association of serum adiponectin concentration and its genetic polymorphism with IAF has not been studied. This study investigated the relationship between serum levels of adiponectin, adiponectin gene polymorphisms, and the risk of developing IAF in a Chinese Han population. <b><i>Methods:</i></b> Patients with IAF (<i>n</i> = 172, IAF group) and healthy individuals (<i>n</i> = 150, control group) were consecutively and randomly recruited and fasting peripheral blood samples were collected. All participants were examined for serum adiponectin concentrations and the polymorphisms SNP45T&gt;G (SmaI locus, rs2241766) and SNP276G&gt;T (BsmI locus, rs1501299) of the adiponectin gene were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Related clinical data from the two groups were also collected. <b><i>Results:</i></b> Plasma adiponectin levels in the IAF group were significantly lower than those in the control group (9.9 ± 2.6 mg/L vs. 16.1 ± 7.0 mg/L, <i>p</i> = 0.006). There were no significant differences among the three genotypes (wild type, mutant heterozygote, and homozygote) of SNP45T&gt;G or SNP276G&gt;T in the prediction value of IAF. The frequency of the T allele of SNP45 T&gt;G was 70.3% in the IAF group and significantly different from that of the control group (71.3%; <i>p</i> = 0.02). In the case of SNP276G&gt;T, the frequency of the G allele was 68.61% in patients with IAF compared to 73.34% in the control group (<i>p</i> = 0.35). Furthermore, a comparison of the clinical data of individuals in the two groups revealed that the left atrial diameter (LAD) in patients in the IAF group was obviously higher than that in the control group (43.3 ± 6.7 mm vs. 37.9 ± 5.1 mm, respectively; <i>p</i> &lt; 0.001). The left ventricular ejection fraction (LVEF) in the IAF group was obviously reduced than that in the control group (54.7 ± 11.9% vs. 60.2 ± 5.6%, respectively; <i>p</i> &lt; 0.001). <b><i>Conclusions:</i></b> Low plasma adiponectin levels were significantly associated with IAF. Hypoadiponectinemia can thus serve as an important factor for the incidence of IAF. The genotypes of SNP45T&gt;G and SNP276G&gt;T in the adiponectin gene may not correlate with the occurrence of IAF. However, our results demonstrate that the T allele of SNP45T&gt;G may be responsible for IAF development in the Chinese Han population.