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Partial resistance to anticoagulation after streptokinase treatment for acute myocardial infarction
D Zahger1, Y Maaravi, Y Matzner
1Department of Internal Medicine, Hadassah University Hospital, Mount Scopus, Israel.
Insights
Patients treated with streptokinase for acute myocardial infarction (AMI) require higher heparin doses and longer times to achieve anticoagulation. This suggests a partial resistance to anticoagulants, potentially increasing reocclusion risk.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Anticoagulant therapy is crucial for managing acute myocardial infarction (AMI).
- Thrombolytic therapy, such as with streptokinase, is a common treatment for AMI.
- Understanding patient response to anticoagulants after thrombolysis is essential for optimizing treatment.
Purpose of the Study:
- To investigate the anticoagulant response in patients previously treated with streptokinase for AMI.
- To compare heparin and warfarin dosage and time to achieve therapeutic anticoagulation in different patient groups.
- To assess potential anticoagulant resistance following streptokinase treatment for AMI.
Main Methods:
- A comparative study involving three patient groups: post-streptokinase AMI, non-thrombolysed AMI, and non-coronary indications.
- Measurement of daily heparin and warfarin requirements to achieve target activated partial thromboplastin time (APTT) and international normalized ratio (INR).
- Analysis of the time required to reach therapeutic anticoagulation levels in each group.
Main Results:
- Patients treated with streptokinase (Group 1) required significantly higher daily heparin doses (37,755 U) compared to controls (30,294 U).
- Achieving adequate anticoagulation took longer in Group 1 patients (5 days for heparin, 5 days for warfarin) versus controls (3 days for heparin, 4 days for warfarin).
- Despite higher doses, Group 1 patients exhibited lower APTT values, indicating potential partial resistance.
Conclusions:
- Patients treated with streptokinase for AMI demonstrate partial resistance to anticoagulation.
- This resistance may necessitate adjusted dosing strategies to achieve therapeutic anticoagulation.
- The findings suggest a potential increased risk of reocclusion in patients treated with streptokinase due to altered anticoagulant response.
Abstract:
This study examines the response of 3 different groups of patients to anticoagulants: 50 patients previously treated with streptokinase for acute myocardial infarction (AMI) (group 1), 24 patients with AMI who had received anticoagulants without prior thrombolysis (group 2) and 11 subjects who received anticoagulants for noncoronary indications (group 3). No significant differences were detected between groups 2 and 3; therefore, they were combined for analysis. After streptokinase, patients required 37,755 +/- 1,516 (mean +/- standard error of the mean) U of heparin per day to achieve the desired activated partial thromboplastin time (APTT). The dosage was 30,294 +/- 1,089 U/day in patients without antecedent thrombolysis (p less than 0.001). Group 1 patients required 5 +/- 0.4 days until adequate anticoagulation was achieved, compared with 3 +/- 0.2 days in the control group (p = 0.01). Despite higher heparin requirements, group 1 patients had a lower APTT value than the other subjects (87 +/- 5 vs 101 +/- 6 seconds, p = 0.08). Group 1 patients required 5 +/- 0.3 days to reach anticoagulation with warfarin versus 4 +/- 0.2 days in groups 2 + 3 (p = 0.05). Comparison of groups 1 and 2 yielded similar, although smaller, differences. Patients treated with streptokinase for AMI seem to be partially resistant to anticoagulation, which may increase the risk of reocclusion.