Background: Cardiovascular risk factors for myocardial infarction (MI) are less frequent in younger than in older MI survivors. Therefore, the thrombotic component of MI may play a more important role at a young age. As activated protein C (APC) provides systemic anticoagulant and anti-inflammatory protection, a low plasma APC level may be an arterial thrombotic risk factor.
Aim: To determine whether there is an association between reduced APC levels and early MI and severe coronary lesions.
Methods: APC was measured in 231 young MI survivors and 231 controls.
Results: Low APC levels were significantly associated with MI. Compared with the fourth quartile, the odds ratio (OR) for APC values in the first quartile was 3.7 [95% confidence interval (CI) = 2.1-6.4], and 3.2 (1.5-7.0) after adjustment for cardiovascular risk factors. Moreover, each decrease of 0.43 ng mL(-1) (1 SD) in APC increased the OR 1.7 times (1.4-2.2), and 1.5 times (1.2-1.9) after adjustment for cardiovascular risk factors. Low APC levels were also associated with the number of coronary arteries affected and with the severity of coronary lesions (P < 0.001).
Conclusions: There is a significant association between low circulating APC levels and both early MI and the extent and severity of coronary atherosclerosis, which might be related to the anticoagulant and anti-inflammatory properties of APC.