The relationship between interleukin-6 polymorphism and the extent of coronary artery disease in patients with acute coronary syndrome

Objectives: We investigated plasma fibrinogen and interleukin-6 (IL-6) levels and the frequency of IL-6 polymorphism in patients with acute coronary syndrome. Study design: A case-control study was conducted in 115 patients who underwent coronary angiography for suspected ischemic heart disease. The patients were classified into two groups according to angiography findings: 65 patients (49 males, 16 females; mean age 61 +/- 10 years) had less extensive coronary artery disease (CAD) (1-vessel stenosis), and 50 patients (36 males, 14 females; mean age 61 +/- 9 years) had extensive CAD (>= 2-vessel stenosis). Fasting blood samples were taken to determine serum lipids, high sensitivity C-reactive protein, IL-6, and fibrinogen levels. The genotypic distribution and the IL-6 C/G-174 polymorphism were determined by polymerase chain reaction. Results: Patients with less extensive CAD had a significantly lower prevalence of positive familial CAD and significantly lower plasma IL-6 and fibrinogen levels compared to those with extensive CAD (p<0.05). IL-6 polymorphism was detected in 20 patients (17.4%), its frequency being significantly higher in patients with extensive CAD (32% vs 6.2%; p<0.001). Conclusion: Our results suggest that the presence of the IL-6 C/G-174 polymorphism and increased IL-6 and fibrinogen levels are strongly associated with the inflammatory system and hemodynamical significance of CAD.