Determination of cardiac troponin I forms in the blood of patients with unstable angina pectoris.

OBJECTIVE

To determine the predominant form in which cardiac troponin I circulates in the bloodstream of unstable angina patients.

DESIGN AND

METHODS

The cardiac troponin I forms released in the bloodstream of 25 patients suffering from unstable angina were examined by using three immunoenzymatic assays: the total cTnI assay for detection of free and complexed cTnI, the IC-TIC assay for detection of the IC and TIC troponin complexes, and the IT-TIC assay for detection of the IT and TIC troponin complexes.

RESULTS

Approximately 60% of patients with unstable angina had at least one positive value in the total cTnI assay or in the IC-TIC assay. Our results demonstrated that the predominant cardiac troponin I form circulating in the bloodstream of patients with unstable angina was the IC complex. Free cTnI, IT, and/or TIC forms were seldom found, the frequency of IT and/or TIC complexes being higher than that observed previously in patients with acute myocardial infarction.

CONCLUSIONS

The release pattern of cTnI in patients suffering from unstable angina is similar to that previously observed in patients with acute myocardial infarction, i.e., a predominance of the IC complex.