Cardiac biomarkers: a review

Cardiac injury can develop secondary to compromise due to disease or drug toxicity, among other causes. The clinical signs of cardiac problems can be confused with those of other conditions, such as respiratory disease. Therefore, specific, sensitive, rapid and inexpensive blood tests for cardiac injury are desirable. Cardiac troponins are uniquely expressed in the myocardium and increase with injury. Changes in serum concentrations of these have been found to be specific and sensitive indicators of such injury. Troponins are phylogenetically highly conserved proteins with > 95% homology between mammals. Thus assays developed for human serum can be used in other species. Natriuretic peptides have been more recently used as indicators of cardiac injury in humans. They are becoming more available for animals but homology is lower, therefore many animal species-specific assays need to be developed. These peptides are sensitive to changes in vasoconstriction and dilation within the heart and are used for the diagnosis and prognosis of heart failure in humans. Assays for endothelins and cardiotrophins have similar potential and are under development and evaluation for human use. Combinations of these tests can be followed by more specialised tests (e.g. echocardiography) to confirm the severity and type of injury that has occurred.Abbreviations AMI acute myocardial infarction - CK-MB creatine kinase muscle/brain - ANP atrial natriuretic peptide - AST asparatate aminotransferase - BNP brain natriuretic peptide - CHF chronic heart failure - CK creatine kinase - CNP C-type natriuretic