Purpose: To evaluate the main components of the fibrinolytic system in patients suffering of acute myocardial infarction (AMI), both in the acute phase and once this has been overcome.
Patients and methods: Components of the fibrinolytic system (i.e., PAI-1, t-PA, fibrinogen, plasminogen, and alpha 2-antiplasmin) were determined in 100 patients with AMI. The studies were performed at AMI and 6 months later, and the findings were compared with those of a control group of 30 people matched with regard to age and sex with the patient group. The statistical analysis of the results was made with the BMPD pack, using Student's t test for comparing quantitative variables and the matched test for paired samples.
Results: At the acute phase the patients showed significant increase of PAI-1 (p < 0.001) and fibrinogen (p < 0.05) concentrations. Plasminogen and alpha 2-antiplasmin rates were lower than in the control group (p < 0.01 and p < 0.005, respectively). In the 6-month study after AMI, significant increase of PAI-1 was found with respect to the control group (p < 0.001). There were also significant differences in the initial PAI-1 rates and the 6-month test (p < 0.05), whereas the increased fibrinogen rates persisted (p < 0.01). Increased antigenic t-PA was found in the patient group before venous occlusion (p < 0.001). Thus, 54 patients (54%) had hypofibrinolysis, due to increased PAI-1 in 41 cases (41%), impaired t-PA release in 13 cases (13%) and both causes in 12 cases (12%).
Conclusions: Fibrinolytic hypofunction was found in this study during the acute phase of myocardial infarction, which was still present six months later, and was due to increased PAI-1 rates in the majority of the cases.