The effect of streptokinase neutralizing antibodies on fibrinolytic activity and reperfusion following streptokinase treatment in acute myocardial infarction

Abstract. Nilsson JB, Nilsson TK, Jansson J‐H, Boman K, Söderberg S, Näslund U (Heart Centre, University Hospital, Umeå; Örebro Medical Centre, Örebro; Skellefteå Hospital, Skellefteå; Sweden). The effect of streptokinase neutralizing antibodies on fibrinolytic activity and reperfusion following streptokinase treatment in acute myocardial infarction. J Intern Med 2002; 252: 405–411. Objectives. To evaluate tissue plasminogen activator (tPA) activity as a measure of fibrinolytic response to treatment with streptokinase (SK) and to relate this to the effect of pretreatment SK antibodies and to successful reperfusion assessed by continuous computerized vectorcardiography (VCG). Setting. Umeå University Hospital. Subjects. A total of 104 patients with acute myocardial infarction (AMI) treated with SK and no history of previous SK treatment were studied. The tPA activity was measured 4 h after the start of treatment. The effect of pre‐existing neutralizing antibodies to SK was analysed with a functional assay in pretreatment samples. Reperfusion was evaluated with VCG. Main outcome measures. Successful reperfusion. Results. Fifty‐five patients (53%) were classified as successfully reperfused. The risk for failed reperfusion was calculated in logistic regression models. In a univariate model, a borderline significant increase in the risk of failed reperfusion was observed in intermediate levels of SK neutralizing antibodies, but not in the highest levels. In a multivariate model, only high tPA activity, >25 U mL^?1, at 4 h (OR 0.17; 95% CI: 0.06–0.51) was associated with a higher rate of reperfusion whilst longer time to treatment (OR 1.17; 95% CI: 1.02–1.35) was associated with a higher risk of failed reperfusion. There was no significant correlation between neutralizing antibodies to SK and tPA activity at 4 h. Conclusion. The SK treatment of AMI induced high levels of tPA activity which were associated with successful reperfusion. The effect of pre‐existing SK antibodies had no significant influence on reperfusion and were not correlated to the fibrinolytic activity obtained.