Usefulness of Cardiac Troponin I as a Prognostic Marker in Non-cardiac Critically Ill Patients

Background : Cardiac troponin I (cTnI) is a specific marker of myocardial injury. It is known that a higher level of cTnI is associated with a poor clinical outcome in patients with acute coronary syndrome. An elevation in cTnI is also observed in various noncardiac critical illnesses. This study evaluated whether cTnI is useful for predicting the prognosis in noncardiac critically ill patients. Methods : From June 2003 to July 2004 at Gyeongsang National University Hospital, we enrolled 215 patients (male: 142, female: 73, mean age: 63 +/- 15 years) who were admitted for critical illness other than acute coronary syndrome at the medical intensive care unit(ICU). The severity score of critical illness (SAPS. and SOFA) was determined and serum cTnI level was measured within 24 hours after admission to the ICU. The mortality rate was compared between the cTnI-positive (>= 0.1 mu g/L) and cTnI-negative (cTnI<0.1 mu g/L) patients at the 10th and 30th day after admission to the ICU. The mean cTnI value was compared between the survivors and non-survivors at the 10th and 30th day after admission to the ICU in the cTnI-positive patients. The correlation between cTnI and the severity of the critical illness score (SAPS. and SOFA) was also analyzed in cTnI-positive patients. Results : 1) The number of cTnI-negative and positive patients were 95(44%) and 120(56%), respectively. 2) The mortality rate at the 10 th and 30 th day after admission to the ICU was significantly higher in the cTnI-positive patients (29%, 41%) than in the cTnI-negative patients (12%, 21%)(p<0.01). 3) In the cTnI-positive patients, the mean value of the cTnI at the 10 th and 30 th day after admission to the ICU was significantly higher in the non-survivors (4.5 +/- 9.2 mu g/L, 3.5 +/- 7.9 mu g/L) than in the survivors(1.8 +/- 3.6 mu g/L, 2.0 +/- 3.9 mu g/L) (p < 0.05). 4) In the cTnI-positive patients, the cTnI level was significantly correlated with the SAPS. score (r=0.24, p<0.001) and SOFA score (r=0.30, p<0.001). Conclusion : The cTnI may be a useful prognostic marker in noncardiac critically ill patients.