[Platelet activation in young men after myocardial infarction: its relation to metabolic coronary risk factors].

Selected parameters of platelet function as well as their relationship with metabolic coronary risk factors are studied in a group of 40 young survivors (aged 30-40 years) of myocardial infarction, now presenting stable coronary disease. Nineteen healthy men, of approximately similar age-span, constituted the control group. The following parameters were determined: platelet survival half-time (via non-isotope method), intraplatelet activity of cyclooxygenase and lipoxygenase pathway of arachidonic acid (by measurements of malondialdehyde concentration before and after incubation with acetylsalicylic acid acid) and 125-I-fibrinogen binding to platelets. Moreover, the plasmatic concentration of total cholesterol, HDL-cholesterol, triglycerides, phospholipids, Apo A and B, total beta lipoproteins, glucose, uric acid as well as percentages of beta, prebeta, alpha lipoproteins and glycosylated hemoglobin were also studied. Platelet survival half-time in patients was significantly shortened (3.64 +/- 1.37 days) when compared with the control group (4.97 +/- 1.7 days). A higher intraplatelet activity of lipoxygenase pathway (2.02 +/- 0.62 and 1.49 +/- 0.54 nmol MDA/10(9) platelets, respectively) was also found. However, activity of cyclooxygenase pathway of arachidonic acid and 125-I-fibrinogen binding to platelets remained unchanged. Shortened platelet survival half-time and the hyperactivity of intraplatelet lipoxygenase pathway correlated with a reduced plasmatic concentration of HDL-cholesterol (r = 0.323, p less than 0.05 and r = -0.451, p less than 0.05, respectively). The remaining parameters of platelet function were not statistically related to metabolic risk factors. The values of platelet function indicators in subgroups of patients divided according to family history of coronary heart disease, oral glucose load test result, and submaximal exercise test result did not differ significantly.(ABSTRACT TRUNCATED AT 250 WORDS)