Effect of pretreatment antistreptokinase antibody and streptococcal infection on the efficacy and dosage of streptokinase in acute myocardial infarction.
OBJECTIVES: The objective of the study is to determine if the presence of antistreptokinase (ASK) antibody in the blood, leads to ineffective thrombolytic therapy with streptokinase (SK) in acute myocardial infarction (AMI) and to investigate if increased dose of streptokinase (2.5 million units) could improve the infarct-related artery (IRA) patency or the clinical outcome in these patients. METHODS: The study was conducted between 1994 and 2001 in 2 institutions; King Fahd Armed Forces Hospital, Jeddah, Saudi Arabia and in Kasr El-Aini Faculty of Medicine, Cairo, Egypt. Fifty consecutive patients with acute myocardial infarction (AMI) were included in this prospective double blind, randomized study. All patients were given the allocated streptokinase dose (1.5 or 2.5 million units) and underwent angiography within 24 hours to establish the anatomy of coronary arteries and the patency of infarct-related artery. Antistreptokinase antibody assay was carried out in a core laboratory. RESULTS: The study results showed that the presence of ASK antibody or the administration of an increased dose of SK had no effect on improving the patency rate of the infarct-related artery. CONCLUSION: The presence of a previous streptococcal infection may not necessarily reduce the effect of SK on the patency of the IRA and/or clinical outcome in patients presenting with AMI. The administration of a larger than currently recommended dose of SK (2.5 million units) did not alter the clinical outcome because it did not improve the patency rate of the IRA. However, a larger study is needed to confirm these observations.