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Evolving concepts in the treatment of acute myocardial infarction
1Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235.
Insights
Early intravenous thrombolytic therapy for acute myocardial infarction improves heart function and survival. Tissue plasminogen activator is effective and safe, with angioplasty potentially beneficial for residual blockages.
Area of Science:
- Cardiology
- Pharmacology
- Interventional Cardiology
Background:
- Transmural acute myocardial infarction requires timely intervention.
- Intravenous thrombolytic therapy has shown promise in improving outcomes.
Purpose of the Study:
- To evaluate the efficacy and safety of thrombolytic agents in acute myocardial infarction.
- To assess the optimal timing for thrombolytic therapy administration.
- To explore adjunctive therapies like heparin, aspirin, and mechanical interventions.
Main Methods:
- Review of recent studies on thrombolytic therapy (streptokinase, tissue plasminogen activator) for acute myocardial infarction.
- Analysis of patient outcomes, including left ventricular function and mortality.
- Evaluation of reperfusion rates, adverse effects, and the role of subsequent treatments.
Main Results:
- Intravenous thrombolytic therapy improves left ventricular function and reduces mortality when given within 3-4 hours of symptom onset.
- Tissue plasminogen activator demonstrates high reperfusion rates (~70%) with a favorable safety profile.
- Adjunctive therapies include heparin and aspirin; elective angioplasty 3 days post-thrombolysis shows preliminary benefit.
Conclusions:
- Early thrombolytic therapy is crucial for acute myocardial infarction management.
- Tissue plasminogen activator is a preferred agent due to efficacy and safety.
- Further research is needed to confirm the benefits of aggressive post-reperfusion mechanical strategies.
Abstract:
Recent studies in patients with transmural acute myocardial infarction have demonstrated that intravenous thrombolytic therapy with streptokinase or tissue plasminogen activator improves left ventricular function and reduces mortality. To accomplish this, these agents must be infused early, ie, within 3 to 4 hours of the onset of chest pain; later administration of the agents exerts no significant beneficial effect. Tissue plasminogen activator appears to be the most effective and safest of the available thrombolytic agents: its intravenous administration is followed by coronary reperfusion in about 70% of patients, and its use is not associated with allergic reactions, a systemic fibrinolytic state, or a prolonged fibrinolytic effect. Once reperfusion has been established with an intravenous thrombolytic agent, intravenous heparin is given for several days, followed by oral aspirin to prevent reocclusion. Since many of these patients have a residual high-grade coronary artery stenosis in the infarct-related artery, mechanical alleviation of the residual stenosis with angioplasty or bypass surgery is an attractive therapy 2 to 4 days after reperfusion, and preliminary data indicate that elective coronary angioplasty 3 days after thrombolytic therapy is beneficial. However, further studies are needed to assess more definitively the use of such an aggressive therapeutic strategy.