troponin, or the troponin complex, is a complex of three regulatory proteins (troponin c, troponin i, and troponin t) that is integral to muscle contraction in skeletal muscle and cardiac muscle, but not smooth muscle. blood troponin levels may be used as a diagnostic marker for stroke, although the sensitivity of this assay is low. assays of cardiac-specific troponins i and t are extensively used as diagnostic and prognostic indicators in the management of myocardial infarction and acute coronary syndrome.