Rapid and specific immunoassay for cardiac troponin I in the diagnosis of myocardial damage.

We evaluated a new immunometric assay for the quantitation of cardiac troponin I with the Behring Opus analyzer. All assay steps are performed automatically by the analyzer, the complete procedure requiring 20 min for the first test result. Total precision (coefficient of variation) varied between 5.6% and 13.0%. Comparison with the Pasteur immunoenzymometric assay showed good correlation (r = 0.959), but the Opus assay gave approximately tenfold higher values. Cardiac troponin I was undetectable (< 0.5 microgram/l) in sera from healthy subjects (n = 46), patients with severe skeletal muscle damage (n = 8), and all but 1 patient with chronic renal failure (n = 39). In patients with myocardial infarction (n = 21), investigated for 4 days after onset by frequent sampling, cardiac troponin I peaked at 20.8 +/- 8.1 h after onset with a mean concentration of 164.8 +/- 361.3 micrograms/l, remaining elevated in 89% of patients on the 4th day. In patients with unstable angina (n = 15), cardiac troponin I measurement was valuable in predicting the type of lesion morphology on coronary angiography and the short-term outcome.