Description

Troponin, a molecular complex that is bound to the thin filament (actin) of striated muscle fibers, acts with intracellular calcium to control the interaction of the thin filament with the thick filament (myosin), thus regulating muscle contraction.

Troponin consists of three subunits: T, which connects the troponin complex and tropomyosin (another cardiac muscle regulatory protein); 1, which prevents muscle contraction in the absence of calcium; and C, which binds calcium. Cardiac Troponin I (MW 22.5 kDa) and the two skeletal muscle isoforms of Troponin I have considerable amino acid sequence homology, but cl contains an additional N-terminal sequence and is highly specific for myocardium.

Clinical studies have demonstrated the release of cTl into the blood stream within hours following acute myocardial infarctions (AMI) or ischemic damage. Elevated levels of cTl are detectable in blood within 4 to 6 hours after the onset of chest pain, reaching peak concentrations in approximately 8 to 28 hours, and remain elevated for 3 to 10 days following AM.

Due to the high myocardial specificity and the long duration of elevation, cTl has become an important marker in the diagnosis and evaluation of patients suspected of having an AMI.

The current guideline of The Joint European Society of Cardiology/American College of Cardiology Committee support the use of cTl as a preferred marker of myocardial injury. Several major studies have shown that cTl is also a predictor of cardiac risk in patients with unstable angina. The American College of Cardiology and the American Heart Association’s current guidelines recommend using troponin results when making treatment decisions regarding unstable angina and non-ST segment elevation MI (NSTEMI).