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Thrombolytic therapy in acute myocardial infarction: review of clinical trials
Insights
Intracoronary streptokinase effectively opens blocked coronary arteries, improving heart function. However, potential risks like bleeding and reocclusion necessitate careful consideration of its use in acute myocardial infarction.
Area of Science:
- Cardiology
- Interventional Cardiology
- Thrombolytic Therapy
Background:
- Intracoronary streptokinase infusion shows high immediate recanalization rates (60-90%) for acute myocardial infarction.
- Published mortality data regarding streptokinase use remains conflicting.
- Assessing the risk/benefit ratio requires evaluating angiography risks, reocclusion, bleeding, and need for interventions like angioplasty or bypass surgery.
Purpose of the Study:
- To evaluate the effectiveness and outcomes of intracoronary streptokinase infusion in patients with acute myocardial infarction.
- To identify factors influencing ejection fraction improvement after intracoronary streptokinase therapy.
- To compare intracoronary versus intravenous streptokinase administration regarding recanalization rates and potential benefits.
Main Methods:
- Analysis of 125 registry patients with paired contrast ventriculograms before and after streptokinase infusion.
- Correlation of ejection fraction improvement with baseline coronary obstruction, collateral vessels, and recanalization status.
- Review of published trials comparing intravenous streptokinase doses and their impact on survival and recanalization.
Main Results:
- Improvement in ejection fraction was associated with incomplete coronary obstruction pre-angiography, presence of collateral vessels, and successful recanalization of complete obstructions.
- Intravenous streptokinase at conventional doses showed improved survival in some trials when initiated within 12 hours of infarction onset.
- Higher doses of intravenous streptokinase yielded lower immediate recanalization rates compared to intracoronary administration.
Conclusions:
- Intracoronary streptokinase is effective for immediate coronary artery recanalization, with functional improvement linked to specific angiographic findings.
- The risks associated with intracoronary streptokinase, including procedural complications and need for further interventions, must be weighed against its benefits.
- Further assessment is needed to determine the risks and benefits of high-dose intravenous streptokinase therapy.
Abstract:
Intracoronary infusion of streptokinase is associated with recanalization rates of 60 to 90% immediately after the procedure. Mortality data in published trials are conflicting. In 125 registry patients who had paired contrast ventriculograms before streptokinase infusion and hospital discharge, improvement in ejection fraction correlated with incomplete coronary obstruction before angiography, the presence of collateral vessels to the infarct area and recanalization of complete obstruction. In assessing the risk/benefit ratio of intracoronary streptokinase infusion, the risks of angiography in the setting of acute myocardial infarction, reocclusion, bleeding and such secondary interventions as angioplasty or bypass surgery must be considered. Intravenous infusion of conventional doses of streptokinase was associated with improved survival in some trials in which therapy began within 12 hours after the onset of infarction. Immediate recanalization rates in patients who received large doses of intravenous streptokinase were lower than those associated with intracoronary streptokinase infusion. The risks and benefits of high-dose intravenous streptokinase administration must still be assessed.