Measurement of cardiac troponin I levels in the emergency department: predictive value for cardiac and all-cause mortality.
OBJECTIVE
To assess the predictive value of cardiac troponin I levels in cardiac and all-cause mortality in patients presenting to an emergency department.


METHODS
A prospective cohort study.


METHODS
The emergency department of a major tertiary teaching hospital in metropolitan Melbourne over a six-week period in 1998.


METHODS
All patients with requests for cardiac enzyme level measurement.


METHODS
Cardiac and all-cause mortality within 30 days of presentation.


RESULTS
424 patients (232 men, 192 women; age range, 16-93 years) were reviewed. The 30-day mortality rate was 7.3% (31/424); in patients with raised levels of both creatine kinase (CK)-MB isoenzyme and troponin I this rate was 27% (7/26; 95% CI, 13%-44%); and in those with troponin I levels above 2 microg/L, but normal CK-MB values, it was 24% (5/21; 95% CI, 5%-43%). The mortality rate in the group with normal results of cardiac markers was 4.3% (14/328; 95% CI, 2.1%-6.5%). Patients with minor increases in troponin I levels (minimal myocardial damage) showed an intermediate 30-day mortality rate (13%, 5/39; 95% CI, 2%-24%). Other predictors of 30-day mortality included age, presentation with shortness of breath, and electrocardiography (ECG) changes diagnostic of acute myocardial infarction or consistent with ischaemia. Cardiovascular causes were responsible for most of the deaths in patients with raised troponin I levels. Multivariate logistic regression analysis showed that raised levels of troponin (> 2.0 microg/L), but not of CK-MB, predict 30-day mortality rate.


CONCLUSIONS
Compared with CK-MB, cardiac troponin I more accurately predicts 30-day mortality rates in patients presenting to the emergency department. Moreover, troponin I levels identify additional groups of patients at increased risk of death not so identified by measuring CK-MB values.
Clinical Biochemistry Unit, Alfred Hospital, Melbourne, VIC.
G
G
Wilcox
P D
PD
Archer
M
M
Bailey
L
L
Dziukas
C F
CF
Lim
H G
HG
Schneider
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003402:Creatine Kinase / Q000097:blood*; D052279:Creatine Kinase, MB Form; D004562:Electrocardiography; D004638:Emergency Treatment; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000401:mortality*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D019210:Troponin I / Q000097:blood*; D014739:Victoria / Q000453:epidemiology
D007527:Isoenzymes; D019210:Troponin I; D003402:Creatine Kinase; D052279:Creatine Kinase, MB Form