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Necropsy evaluation in seven patients with evolving acute myocardial infarction treated with thrombolytic therapy
Insights
Coronary artery recanalization with streptokinase for acute myocardial infarction (MI) depends on thrombus morphology. Successful recanalization shows atherosclerotic plaques, while failures involve hemorrhage or complex thrombi, impacting infarct necrosis patterns.
Area of Science:
- Cardiovascular Pathology
- Interventional Cardiology
- Myocardial Infarction Research
Background:
- Systemic and intracoronary streptokinase can recanalize coronary arteries in acute myocardial infarction (MI).
- Thrombolysis failure occurs in some patients due to unknown reasons.
- Understanding the histologic basis of thrombolysis success or failure is crucial.
Purpose of the Study:
- To investigate the coronary and myocardial histologic characteristics in patients with acute myocardial infarction (MI) who underwent streptokinase therapy.
- To compare the morphology of coronary occlusions in patients with successful versus unsuccessful recanalization.
- To correlate reperfusion patterns with myocardial necrosis in successfully treated MI patients.
Main Methods:
- Histologic examination of serial sections from occluded coronary arteries and heart slices.
- Light microscopy was used to analyze infarct vessel morphology and myocardial damage.
- Nitroblue tetrazium staining delineated areas of myocardial infarction (MI).
Main Results:
- Successfully recanalized arteries (n=3) showed obstructive fibrous atherosclerotic plaques.
- Unsuccessful recanalization (n=4) was associated with intramural hemorrhage, complex thrombi, or ruptured atherosclerotic plaques.
- Reperfused infarcts exhibited contraction band necrosis, while non-reperfusion MIs showed coagulation necrosis.
Conclusions:
- The success of coronary artery recanalization with streptokinase is influenced by the morphologic characteristics of the occlusion.
- Different patterns of myocardial necrosis are observed depending on reperfusion status after thrombolysis.
- Histologic assessment provides insight into thrombolysis outcomes and reperfusion injury in acute myocardial infarction (MI).
Abstract:
Systemic and intracoronary streptokinase application may recanalize a coronary artery occluded by a thrombus in patients with acute myocardial infarction (MI). However, thrombolysis fails in a number of patients for unknown reasons. The coronary and myocardial histologic characteristics were studied in 3 patients in whom recanalization was successful without subsequent reocclusion, and in 4 patients in whom recanalization was unsuccessful. All patients died within 4 weeks after the acute intervention. Serial sections from the angiographically localized occlusive site of the infarct vessel, and transverse slices of the heart stained with nitroblue tetrazolium for delineation of MI, were examined by light microscopy. Successfully recanalized arteries were patent at necropsy and showed obstructive fibrous atherosclerotic plaques. Among patients in whom recanalization was unsuccessful, 1 patient had occlusions from nonatherosclerotic intramural hemorrhage and 1 from persisting long, mixed old and fresh thrombus, and 2 patients had high-grade obstructions from ruptured atherosclerotic plaques with intimal hemorrhage and residual clot. Reperfused infarct tissue consisted predominantly of contraction band necroses, whereas MIs without reperfusion showed coagulation necroses of the muscle fibers. The results suggest that the success of recanalization depends, in part, on the morphologic features of the coronary occlusion, and that reperfusion after successful thrombolysis may lead to a different pattern of muscle fiber necrosis in the irreversibly injured infarct areas.