Background: Cardiac Troponins (cTn) are useful in unstable angina (UA). Moreover the different elevation patterns that can be observed in this condition seem to have different prognostic implications.
Aim: To study cTn kinetics and cTn nadir in patients with UA, defined as angina at rest within the last 24 hours before admission accompanied by ischemic ECG changes and no myocardial infarction (MI) enzymatic criteria.
Population and methods: Samples were collected from 156 patients for cardiac enzymes and cTnI at admission and at 6, 12, 18 and 24 hours. The chemilluminescence method (Access/Sanofi Pasteur) was used for cTnI. The primary end-point at 30 days was the combined occurrence of death, MI and recurrent ischemia.
Results: All determinations were below 0.10 ng/ml (group N) in 114 patients and the other 42 pts (group P) had at least one value equal to or above 0.10 ng/ml. The primary endpoint was observed in 24.6% of group N pts compared with 45.2% of group P pts (p = 0.02). Three different patterns of cTnI kinetics were observed. This enabled the identification of a subgroup--group N pts with increasing cTnI values within the first 12 hours and a total differential value > or = 0.03 ng/ml--with an increased risk (50.0% versus 21.4%--p = 0.02--Kaplan-Meier test).
Conclusion: Besides the prognostic value conferred by cTnI elevation, cTnI kinetics analysis established another sub-group of patients with an adverse prognosis at 30 days follow-up, despite having a negative cTnI.