Interleukin 6 G-174C Polymorphism Influences Outcome Following Coronary Revascularization Surgery


  • Mohamad N. Bittar
  • John A. Carey
  • James Barnard
  • James E. Fildes
  • Vera Pravica
  • Nizar Yonan
  • Ian V. Hutchinson



Background: Levels of the proinflammatory cytokine interleukin 6 (IL-6) increase after surgery. The functional polymorphism in the IL-6 promoter region, G-174C, is associated with an increased risk of coronary heart disease. We investigated the genetic predisposition in IL-6 response to coronary revascularization and studied the association between the G-174C polymorphism, IL-6 levels, and clinical outcomes of surgery.

Methods: DNA was obtained from 96 consecutive patients who underwent elective coronary revascularization. Patients were genotyped for the IL-6 G-174C polymorphism by means of sequence-specific primer-polymerase chain reaction analysis. IL-6 levels were measured with an enzyme-linked immunosorbent assay on serum samples taken 3 hours postoperatively. IL-6 levels and genotypes (CC, CG, and GG) were correlated with perioperative clinical data.

Results: The prevalences of the CC, CG, and GG IL-6 -174 genotypes were 8%, 54%, and 38%, respectively. Patients homozygous for the C allele had higher circulating levels of IL-6 postoperatively than the patients with the CG and GG genotypes (P = .09). Patients homozygous for the G allele had a significantly lower incidence of postoperative atrial fibrillation (P = .032) and a shorter hospital stay (P = .005). This result remained statistically significant following risk stratification. The severity of coronary artery disease and a higher number of bypass grafts were associated with a significant increase in IL-6 level postoperatively (P = .028, and P = .005, respectively). Higher levels of IL-6 were associated with increased blood loss postoperatively (P = .016)

Conclusions: The C allele is associated with higher postoperative IL-6 levels and a less favorable clinical outcome. The G-174C polymorphism is related to the outcome after coronary revascularization.


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How to Cite

Bittar, M. N., Carey, J. A., Barnard, J., Fildes, J. E., Pravica, V., Yonan, N., & Hutchinson, I. V. (2005). Interleukin 6 G-174C Polymorphism Influences Outcome Following Coronary Revascularization Surgery. The Heart Surgery Forum, 8(3), E140-E145.