Myocardial injury in critically ill patients: relation to increased cardiac troponin I and hospital mortality.

OBJECTIVE: To examine the relationship between myocardial injury, assessed by cardiac troponin I (cTnI) levels, and outcome in selected critically ill patients without acute coronary syndromes or cardiac dysfunction. DESIGN AND
SETTING: Prospective, observational study in the emergency ICU of a university teaching hospital. POPULATION: Over a 6-month period, 217 consecutive patients admitted to the ICU were studied. METHODS AND
RESULTS: cTnI assays were performed in all patients on admission to the ICU. The incidence of myocardial injury, defined by cTnI level > 0.1 ng/mL, was 32% (69 of 217 patients). Overall mortality was 27% (58 of 217 patients). Patients with myocardial injury had a mortality rate of 51%, compared with only 16% mortality for those without myocardial injury (p < 0.001). The hospital mortality rate was highest among older patients (71 +/- 14% vs 58.5 +/- 20%, p < 0.0001) and patients with higher simplified acute physiology scale (SAPS) II score (62 +/- 25% vs 37 +/- 17%, p < 0.0001). Mechanical ventilation was associated with higher in-hospital death (50% vs 31%, for patients who died in the hospital vs those who were discharged alive; p = 0.03). Elevated blood levels of cTnI were found to be independently associated with hospital mortality, regardless of the presence of SAPS II score and mechanical ventilation, in the logistic regression analysis (odds ratio, 2.09; 95% confidence interval, 1.06 to 4.11; p = 0.01).
CONCLUSIONS: This study demonstrates the high frequency of myocardial injury (32%) in critically ill patients without acute coronary syndromes or cardiac dysfunction on admission to ICU. Myocardial injury is an independent determinant of hospital mortality. Assessment of myocardial injury on admission to ICU would make it possible to identify patients at increased risk of death.