Measurement of troponin in cardiomyopathies

Troponins are thin myofilament proteins that regulate the contraction of cardiac and skeletal muscle. The cardio-specific troponin I (TnI) and T (TnT) proteins are sensitive and specific biomarkers of myocardial injury which over the past twenty years have revolutionised the diagnosis and management of myocardial infarction. With the advent of high sensitivity assays the role for cardiac troponins is possibly expanding. Elevated levels are associated with adverse cardiovascular events and mortality in heart failure and the general population. Studies in cardiomyopathies are generally small with <200 patients, but serum troponin levels can be chronically raised and detect subclinical myocyte damage. This review examines all major published studies of cardiac troponin measurement in cardiomyopathies. There is considerable variability among studies regarding assays used and definitions of abnormal results but elevated troponin levels are almost invariably related to poor prognosis and their negative predictive value is important.