Biochemical Markers of Myocardial Damage

Heart diseases, especially coronary artery diseases (CAD), are the leading causes of morbidity and mortality in developed countries. Effective therapy is available to ensure patient survival and to prevent long term sequelae after an acute ischemic event caused by CAD, but appropriate therapy requires rapid and accurate diagnosis. Research into the pathology of CAD have demonstrated the usefulness of measuring concentrations of chemicals released from the injured cardiac muscle can aid the diagnosis of diseases caused by myocardial ischemia. Since the mid-1950s successively better biochemical markers have been described in research publications and applied for the clinical diagnosis of acute ischemic myocardial injury. Aspartate aminotransferase of the 1950s was replaced by other cytosolic enzymes such as lactate dehydrogenase, creatine kinase and their isoenzymes that exhibited better cardiac specificity. With the availability of immunoassays, other muscle proteins, that had no enzymatic activity, were also added to the diagnostic arsenal but their limited tissue specificity and sensitivity lead to suboptimal diagnostic performance. After the discovery that cardiac troponins I and T have the desired specificity, they have replaced the cytosolic enzymes in the role of diagnosing myocardial ischemia and infarction. The use of the troponins provided new knowledge that led to revision and redefinition of ischemic myocardial injury as well as the introduction of biochemicals for estimation of the probability of future ischemic myocardial events. These markers, known as cardiac risk markers, evolved from the diagnostic markers such as CK-MB or troponins, but markers of inflammation also belong to these groups of diagnostic chemicals. This review article presents a brief summary of the most significant developments in the field of biochemical markers of cardiac injury and summarizes the most recent significant recommendations regarding the use of the cardiac markers in clinical practice.