Summary
Little data is available regarding the activated form of factor XIIa (FXIIa) in survivors
of myocardial infarction. 292 Caucasian patients characterised for extent of coronary
atheroma by angiography and for a past history of myocardial infarction and 77 healthy
controls were included in the study. To investigate the relationship between coronary
artery disease, activated factor XII and other circulating factors, we studied levels
of FXIIa, cholesterol, triglycerides, fasting insulin, fibrinogen, FVII:C, t-PA antigen
and PAI-1 antigen. Factor XIIa levels were higher in all patients [2.5 (2.3-2.6) ng/ml]
and in patients with a history of MI [2.6 (2.4-2.9) ng/ml] than in controls [1.9 (1.7-2.1)
ng/ml], p <0.0001. In patients, FXIIa levels positively correlated with FVII:C, BMI,
cholesterol, insulin, PAI-1 antigen, t-PA antigen and triglycerides. In controls FXIIa
levels only correlated with PAI-1 antigen and triglycerides. FXIIa levels were strongly
associated with extent of coronary stenosis: 2.8 (2.6-3.1) ng/ml and 2.6 (2.3-2.9
ng/ml) in those with 2 and 3 vessels stenosed compared to 2.1 (1.9-2.3) ng/ml in those
with 0 vessel stenosed (p = 0.0004). Activated FXII relates to both extent of coronary
atheroma and to a past history of myocardial infarction and clusters with features
of insulin resistance.