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Myocardial injury markers
Last reviewed: 23.04.2024
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Myocardial infarction is an acute disease that arises from a sharp discrepancy between myocardial oxygen demand and its delivery through the coronary arteries, which results in the development of necrosis of a part of the heart muscle.
At present, it is considered proven that the cause of myocardial infarction in more than 80% of cases is intracoronary thrombosis, which usually occurs on the site of an atherosclerotic plaque with a damaged surface.
Myocardial infarction is a dynamic process, the development of which occurs both in time and in space. As a result of defects occurring in the cytoplasmic membranes of myocardiocytes, proteins and enzymes localized in the cytoplasm enter the patient's blood at a rate that depends primarily on the size of their molecules.
Over the past two decades, numerous randomized studies have been conducted to evaluate the efficacy and safety of the diagnosis and treatment of myocardial infarction. The results of the studies were used as the basis for the guidelines for managing patients with myocardial infarction. In 2000, a joint document of the European Cardiological Society (ESO) and the American College of Cardiology (ACC) was published.
In the above clinical recommendations indicate that cardiac troponins T and I have almost absolute specificity for myocardial tissue, as well as high sensitivity, which allows detecting even microscopic sites of myocardial damage. The use of troponin studies for the diagnosis of myocardial infarction is one of the recommendations of the first class of evidence. Cardiac troponins should be determined on admission and again after 6-12 hours. If the results of the studies are negative and the risk of myocardial infarction is high according to clinical data, the test is repeated after 12-24 hours. In the case of repeated myocardial infarction, the determination of the concentration of troponins is carried out through 4- 6 hours from the onset of recurrence and then again after 6-12 hours.
Determination of myoglobin activity in serum and / or CC-MB activity should be carried out at a recent (less than 6 hours) clinical symptoms and in patients with repeated ischemia after a recent (less than 2 weeks) myocardial infarction for relapse. In the case of a recurrence of myocardial infarction, the importance of studies of myoglobin and KK-MB increases, since the content of troponins may remain elevated because of the initial episode of myocardial necrosis.
Patients with chest pain and a concentration of T / I troponins above the upper limit of the reference value are treated as having "myocardial damage" (hospitalization and close observation is necessary).
Clinical recommendations unequivocally indicate that the study of the activity of AST, LDH and its isoenzymes should not be used to diagnose myocardial infarction.
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