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Antithrombotic therapy for acute myocardial infarction
C J O'Donnell1, P M Ridker, P R Hebert
1Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02215, USA.
Insights
Aspirin is beneficial for acute myocardial infarction, but adding heparin shows no clear benefit and increases bleeding risk. Further trials are needed to optimize antithrombotic therapy for heart attack patients.
Area of Science:
- Cardiology
- Thrombosis Research
- Clinical Trials
Background:
- Antithrombotic therapy, particularly aspirin, significantly reduces mortality, reinfarction, and stroke in acute myocardial infarction (AMI).
- The optimal antithrombotic regimen for AMI remains controversial, especially regarding the addition of heparin.
- Heparin use with aspirin and thrombolytic therapy has not demonstrated consistent mortality or patency benefits and is associated with increased bleeding risks.
Purpose of the Study:
- To evaluate the optimal antithrombotic regimen for acute myocardial infarction (AMI).
- To compare the risks and benefits of aspirin alone versus aspirin plus heparin in patients not receiving thrombolytic therapy.
- To assess the efficacy and safety of aspirin plus intravenous heparin and aspirin plus intravenous hirudin in AMI.
Main Methods:
- Review of existing randomized trial data on antithrombotic therapy in AMI.
- Analysis of the benefits and risks of aspirin, heparin, and thrombolytic therapy combinations.
- Description of the First American Study of Infarct Survival (ASIS-1) trial design.
Main Results:
- Aspirin provides substantial benefits in reducing mortality, reinfarction, and stroke in AMI patients.
- Adding heparin to aspirin and thrombolytic therapy does not consistently improve outcomes and increases bleeding events.
- Current data are insufficient to compare heparin addition to aspirin alone in patients not receiving thrombolytics.
Conclusions:
- Further large-scale trials are necessary to determine optimal antithrombotic strategies for AMI.
- The balance of benefits and risks for current and novel antithrombotic regimens needs further investigation.
- The ASIS-1 trial will provide crucial data on aspirin, heparin, and hirudin in AMI patients not receiving thrombolytics.
Abstract:
Antithrombotic therapy is clearly beneficial in the treatment of acute myocardial infarction, but the optimal regimen is controversial. Treatment with aspirin leads to substantial and significant reductions in rates of mortality, reinfarction and stroke in patients with acute myocardial infarction, and the benefits are additive with those of thrombolytic therapy. It is unclear whether heparin confers additional net benefits over aspirin alone. In patients receiving aspirin and thrombolytic therapy, there is no mortality benefit from adding delayed subcutaneous heparin, no consistent patency benefit from adding immediate intravenous heparin and no reduction in mortality from adding immediate intravenous heparin, at least for patients treated with streptokinase. However, heparin is consistently associated with increased rates of intracranial and other serious bleeding events when used with both aspirin and thrombolytic therapy. Existing data support the need for further large-scale trials of current and newer antithrombotic regimens in acute myocardial infarction to assess the balance of benefits and risks of these regimens compared with that for aspirin alone. In patients not receiving thrombolytic therapy, randomized trial data are currently insufficient to adequately compare the benefits and risks of adding heparin to aspirin alone. The First American Study of Infarct Survival (ASIS-1) will directly compare the balance of risks and benefits of aspirin alone, aspirin plus intravenous heparin and aspirin plus intravenous hirudin in patients with acute myocardial infarction not receiving thrombolytic therapy.