Streptokinase antibodies inhibit reperfusion during thrombolytic therapy with streptokinase in acute myocardial infarction

Objectives. To evaluate the influence of pretreatment IgG against streptoki nase on the outcome of streptokinase treatment in acute myocardial infarcti on, Setting. Coronary care unit. Design. From 88 patients admitted to the coronary care unit due to chest pa in, blood samples were taken for determination of the pre-existing titre of antibodies against streptokinase. The patients were treated and monitored according to standard protocols. Fifty of the patients received thrombalyti c therapy with streptokinase due to acute myocardial infarction and were mo nitored with continuous dynamic vectorcardiography, making possible the con tinuous analysis of ST- and QRS-vector changes and determination of the eve nt of reperfusion, None of these 50 patients had been given streptokinase t herapy previously, Results, According to the vectorcardiographic criteria 21(42%) patients had signs of early (within 2 h) reperfusion after streptokinase therapy, These patients had lower pre-existing antibody titres than patients without sign s of reperfusion (mean values 0.20 and 0.45 arbitrary units, P = 0.01). Non e of the patients with a titre higher than 0.50 arbitrary units (nine patie nts) had signs of early reperfusion. Of the 41 patients with a titre lower than 0.50 arbitrary units 52.5% had signs of early reperfusion. Conclusion. The present investigation indicates that pre-existing streptoki nase antibodies play an important role in reperfusion failure during thromb olytic therapy with streptokinase in acute myocardial infarction. Therefore , the determination of streptokinase antibodies may differentiate between t hose patients who may benefit from streptokinase treatment and those who sh ould be treated with some other regime.