Impairment of plasma fibrinolysis in young survivors of myocardial infarction with silent ischaemia.

The aim of this study was to compare fibrinolytic parameters in two subgroups of young survivors of myocardial infarction: group A (n = 14) with silent myocardial ischaemia and group B (n = 15) without silent myocardial ischaemia, as assessed by 24 h Holter electrocardiogram monitoring. Only men aged 33-46 years who were in a stable condition at least 6 months after the acute event were included in the survey. All patients were normolipaemic or had only mild hyperlipidaemia, non-diabetic, normotensive, non-current smokers and with a normal body mass index. The control group consisted of 15 age-matched healthy men. Blood samples were taken at 7.30 a.m. In the group A patients, we found higher mean levels of tissue plasminogen activator (t-PA) total antigen (11.1 versus 6.9 ng/ml, P < 0.01), its inhibitor plasminogen activator inhibitor-1 (PAI-1) antigen (58.1 versus 34.8 ng/ml, P < 0.01), PAI-1 activity (4.9 versus 3.4 U/ml, P < 0.05) and tPA-PAI-1 complexes (5.1 versus 3.5 ng/ml, P < 0.05) as well as a lower level of t-PA activity (0.5 versus 0.8 IU/ml, P < 0.01) and free t-PA antigen (0.8 versus 1.3 ng/ml, P < 0.01) compared with the controls. However, group A patients exhibited higher PAI-1 antigen levels (58.1 versus 41.6 ng/ml, P < 0.05) than those without silent ischaemia. There were no differences between group B and controls in any of the parameters measured. Our results indicate that patients with more severe disease, as revealed by silent myocardial ischaemia, had lower levels of free t-PA as a result of the excess of PAI-1.