Time course of platelet a granule release in acute myocardial infarction treated with streptokinase

Abstract

Objective - To determine the time course of platelet a granule release in patients with acute myocardial infarction treated with streptokinase. Design - A prospective study. Setting - Coronary care unit. Patients - Nine with myocardial infarction treated with both streptokinase and aspirin, and nine with acute chest pain but without myocardial infarction, who were treated with aspirin only. Methods - All patients received 250 mg aspirin on admission and 150 mg once daily thereafter. All patients who fulfilled the indications for streptokinase received 1.5 megaunits, in a single infusion. After the initial medication, serial measurements of plasma β thromboglobulin and plasma platelet factor 4 were performed at fixed intervals after the onset of chest pain. The primary endpoint sought was the peak value of β thromboglobulin and platelet factor 4 in each individual. Results - The median peak plasma,a thromboglobulin in the infarction group was substantially higher than in those without infarction, at 37 (range 12 to 210) v 15 (9 to 36) mg/litre, P < 0.01. The corresponding values for plasma platelet factor 4 were 4.6 (2.4 to 60.0) v 2.2 (< 2 to 8.5) mg/litre, P < 0.01. Increased values were seen only within the first 12 h after onset of chest pain, and after 12 h there was no difference between the patients with myocardial infarction and those without. Aspirin treatment did not abolish a granule release. Conclusions - In patients with acute myocardial infarction treated with streptokinase the content of the a granules is released within the first 12 h after the onset of chest pain. Aspirin apparently does not abolish this release.