Is endothelin gene polymorphism associated with postoperative atrial fibrillation in patients undergoing coronary artery bypass grafting?

BACKGROUND: The mechanism of development of atrial fibrillation (AF) in patients undergoing coronary artery bypass grafting (CABG) has not been clearly defined, and the involvement of multiple factors such as advanced age, withdrawal of β-blockers, inadequate atrial protection, and electrolyte imbalance, particularly hypomagnesemia has been documented by several authors. Despite all the available pharmacologic prophylaxis, incidence of AF still remains high in this group of patients. This unexplained cause could be genetic inheritance of endothelin-1 (ET-1) gene which is thought to have a pro-arrhythmogenic effect.

AIM: This study aims to investigate the relationship between plasma ET-1 concentrations, ET-1 gene polymorphisms in loci -1370 T/G, -134 (3A/4A) Ins/del, Lys198Asn (G/T), and occurrence of AF in patients undergoing CABG.

METHODOLOGY: Ninety-eight nonrelated, nondiabetic patients over a period of 4 years undergoing routine CABG were selected for the present study. All patients were genotyped for three single nucleotide polymorphisms (SNPs) in loci -1370 T/G, -134 (3A/4A) Ins/del, and Lys198Asn (G/T) in the ET-1 gene by gene sequencing. The plasma ET-1 concentrations were measured using an ET immunoassay.

RESULTS: Plasma ET-1 concentrations were higher in AF+ group (P = 0.001) as compared to AF- group. The allele frequencies between AF+ and AF- group were significantly different only with respect to the Lys198Asn (G/T) SNP of the ET-1 gene.

CONCLUSION: The study described the possible correlation of polymorphism of ET gene in CABG population from India. The ET-1 gene might play a disease-modifying role in atrial fibrillation.