Risk of coronary heart disease and activation of factor XII in middle-aged men.

Increased activity is known to be present in the extrinsic, intrinsic, and final common pathways of the hemostatic system in men at high risk of coronary heart disease (CHD), but the status of the contact system of coagulation in this condition is uncertain. Plasma levels of activated factor XII (XIIa), the initial product of contact activation, have therefore been measured by ELISA in 2464 men aged 51 to 62 years, clinically free of CHD, who were taking part in a prospective cardiovascular survey based in general medical practices. Statistically significant, independent, and positive associations of XIIa were found with serum cholesterol and triglyceride concentrations, blood pressure, body mass index, factor VII activity, plasma fibrinogen concentration, and tobacco smoking, all associated with CHD. Plasma XIIa also increased with recent alcohol intake. Men in the highest quintile of risk according to their conventional risk factors had a mean XIIa of 2.07 ng/mL (95% confidence interval 1.99-2.16), 31% higher than that of men in the lowest quintile (1.58; 95% confidence interval 1.51-1.65). Thus, the contact system of coagulation appears to be activated when CHD risk is increased. Furthermore, the independent associations of XIIa with the major conventional CHD risk factors and its broad range of values in the general population (0.1 to 12.5 ng/mL), combined with a relatively low day-to-day variability in individuals (the within-person component of its total variation being 14.7%), suggest its potential usefulness as a marker of atherosclerotic vascular damage.