An update on cardiac troponins as circulating biomarkers in heart failure.

Circulating troponins and natriuretic peptides are the only biomarkers specifically released from cardiac myocytes that can be determined with robust and sensitive analytical methods, even in healthy subjects. These intracellular proteins are released from reversibly or irreversibly damaged cardiac myocytes into the bloodstream by mechanisms that are not entirely clear. The recent introduction of a new generation of highly sensitive assays of cardiac troponin I or T has not only improved the early diagnosis of acute myocardial infarction but also suggested that there are several causes for troponin release other than acute coronary syndromes. Circulating troponins are elevated in patients with acute or chronic heart failure and are strongly associated with outcome, independently of natriuretic peptides, the benchmark biomarkers in heart failure. In the absence of further experimental evidences, the pathophysiologic basis for the elevation of circulating cardiac troponins in patients with stable chronic heart failure remains speculative.