Moderately elevated serum troponin concentrations are associated with increased morbidity and mortality rates in surgical intensive care unit patients

Objective: To determine the significance of moderate elevations of serum troponin I in a surgical intensive care unit patient population in terms of its impact on indexes of outcome including mortality, morbidity, and hospital and intensive care unit length of stay. Design: Retrospective chart review and analysis of clinical data. Setting: A surgical intensive care unit at a tertiary care hospital. Patients: From the 27-month surgical intensive care unit database of admissions, 869 patients with serum troponin I determinations during their admission were identified. Patients who had cardiac surgery were excluded. Interventions: None. Measurements and Results: Patients were divided into four groups based on their maximum serum troponin I concentrations. Hospital mortality, incidence of myocardial infarction, and hospital and intensive care unit length of stays were compared. Patients with moderate elevations of serum troponin I (0.4-2.0 μg/L) had a significantly higher mortality rate (chi-square = 32.57, p < .0001) and longer length of intensive care unit and hospital stays (p < .0005) when compared with patients without similar elevations. Within the range of moderately elevated troponin concentrations, higher titers were associated with increasing mortality risk, longer hospital and intensive care unit stays, and a higher incidence of myocardial infarction. The use of a β-blocker and aspirin was associated with better survival for patients with maximum serum troponin concentrations ≥2 μg/L. Conclusion: Moderate elevations of serum troponin I, which are below the threshold required to diagnose overt myocardial infarction, may reflect ongoing myocardial injury in the critically ill and are associated with a higher mortality rate and longer hospital and intensive care unit length of stays. The use of β-blockers and aspirin is associated with better outcomes for this subset of patients.