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Complete necrosis of all myocardial cells within the area at risk requires at least 2–4 h or longer depending on the presence of collateral circulation to the ischemic zone, persistent or intermittent coronary arterial occlusion, the sensitivity of the myocytes to ischemia, pre-conditioning, and/or, finally, individual demand for myocardial oxygen and nutrients. Coronary plaque disruption and partial coronary occlusion may be present.Īfter the onset of insufficient myocardial oxygneation, it takes several hours before larger amounts of cell death occur and myocardial necrosis can be identified by macroscopic or microscopic post-mortem examination. This syndrome has a reduced risk of death and usually is not associated with left ventricular dysfunction. In this syndrome the troponin and/or other biomarkers are not raised and the ECG changes of ST depression or elevation may be transient. The third syndrome is (c) acute coronary syndrome with unstable angina. The patient usually has intracoronary thrombus and some evidence of left ventricular dysfunction, the risk of death in this intermediate state is 8–12%.
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(b) The patient may have an acute coronary syndrome with myocardial necrosis in which case the troponin although elevated is less than 1 ng/ml.
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These patients usually have a complete coronary occlusion, evidence of left ventricular dysfunction and ECG changes of ST elevation, ST depression, or T wave inversion and the risk of death in this syndrome is 12–15%. Ī consensus report the British Cardiovascular Society developed the definition into three clinical categories (a) Acute Coronary Syndrome (ACS) with clinical myocardial infarction in which there is a raised troponin greater than 1 ng/ml± raised CK-MB or AccuTn1 greater than 0.5 ng/ml. The report of the original task force was published simultaneously in the European Heart Journal and the Journal of the American College of Cardiology in 2000 and later updated by a joint ESC/ACCF/AHA/WHF task force. In order to improve the accuracy of the diagnosis of myocardial infarction (MI) for clinicians and clinical scientists, multinational task forces met in 1999–2000 under the auspices of the European Society of Cardiology (ESC), the American College of Cardiology Foundation (ACCF), the American Heart Association (AHA), and the World Heart Federation (WHF) in order to develop a simple, clinically oriented, universal definition for MI that could be employed both in daily clinical practice and in clinical investigation.