Interaction between cigarette smoking and high-sensitivity C-reactive protein in the development of coronary vasospasm in patients without hemodynamically significant coronary artery disease

Background: Interaction between 2 major risk factors, cigarette smoking and high-sensitivity C-reactive protein (hs-CRP), has not been evaluated in patients with coronary vasospasm (CV) without hemodynamically significant coronary artery disease. Methods: From 1999 to 2005, patients undergoing diagnostic coronary angiography with or without proven CV and without coronary stenosis >50% were evaluated. A total of 621 subjects (335 and 286 with and without CV, respectively) were enrolled in the study. The levels of hs-CRP, measured immediately before coronary angiography, were examined in a subset of 314 patients. Results: Subjects with CV were likely to be older, men, current smokers, and have high hs-CRP levels. The most significant factors for CV were smoking and hs-CRP. In the nonsmoker group, elevated risk of developing CV was only demonstrated in patients with the highest hs-CRP tertile (>5.01 mg/L, P = 0.012). In the smoker group, however, a positively monotonic trend of association was demonstrated between hs-CRP tertile and CV risk, with multivariate-adjusted odds ratios of 1.11, 3.09 (P = 0.012), and 4.12 by the hs-CRP tertiles, suggesting that smokers developed CV at a lower hs-CRP level than nonsmokers and there was a positive interaction between smoking and hs-CRP. Conclusions: The smokers developed CV at a lower hs-CRP level compared with the nonsmokers. A positive interaction between smoking and hs-CRP was demonstrated for this disease in our study population.