Cardiac dysfunction is an important predictor of outcome in ICU patients but is not identified by increased troponin I

Purpose: To determine whether clinically recognized cardiac dysfunction and subclinical myocardial infarction identified by increased troponin I are important determinants of mortality among ICU patients. Methods: Serial daily troponin I measurements were obtained in 251 consecutive patients admitted to the medical intensive care unit. Clinical assessment as to the presence or absence of cardiac dysfunction was made by the medical care teams. The criteria for cardiac dysfunction was taken from the Organ System Failure Index (J Clin Invest 1990; 86:474) and defined as follows: presence of acute myocardial infarction, cardiac arrest, or congestive heart failure. Results: The incidence of myocardial injury detected by cardiac troponin I was 15.1% (38 of 251 patients). The mortality rate for patients with elevated levels of cardiac troponin I was greater than the mortality rate for patients without elevated levels, however this difference was not statistically significant (26.3% vs 16.4%; P=0.143). There were 50 patients classified as having cardiac dysfunction (40% with elevated troponin I levels, 60% without elevated troponin I levels). The mortality rate for patients classified as having cardiac dysfunction was significantly greater than the mortality rate for patients without cardiac dysfunction (48.0% vs 10.5%; P < 0.001). Multivariate analysis controlling for confounding covariates demonstrated that cardiac dysfunction was an independent determinant of hospital mortality (adjusted odds ratio=4.05; 95% CI=2.62 to 6.26; P=0.001). Conclusions: Clinically recognized cardiac dysfunction is an important predictor of mortality in ICU patients. Subclinical myocardial infarction identified by increased troponin I does not independently identify patients with increased risk of mortality.