[Markers of hemostasis and myocardial infarction in persons under 40 years of age].

Coronary disease before the age of 40 has special clinical and pathogenic features. The authors sought evidence of the existence of abnormalities of hemostasis markers in 39 patients aged under 40, several weeks after a myocardial infarction (MI). Blood samples were drawn a mean of 8 months after the MI. These laboratory studies included assay of C and S proteins, fibrinogen, clotting factors VII and VIII and antithrombin III, as well as detection of any possible circulating anticoagulant. Plasma levels of platelet factor 4 (PT4) and of beta-thromboglobulin (BTG) were measured in the same sample, enabling determination of the BTG/PF4 ratio. Only fibrinogen and plasma levels of platelet proteins were abnormal, revealing a significant difference between patients with multi-vessel disease and those with single vessel disease or free of severe angiographic lesions. Platelet activation appeared to persist some time after the MI, chiefly in patients with multi-vessel disease, and showing no relation to either age or treatment. Conclusions require prudence in view of difficulties in interpreting plasma assays of PF4 and of BTG.