Combined cardiac marker approach with adjunct two-dimensional echocardiography to diagnose acute myocardial infarction in the emergency department.
OBJECTIVE
To evaluate a combined cardiac marker approach with adjunct two-dimensional echocardiography in diagnosing acute myocardial infarction (AMI) in the emergency department.


METHODS
This prospective, cohort study enrolled 190 patients aged 18 years and older who presented to the ED of a county teaching hospital and were admitted with chest pain suggestive of AMI. A standardized history and physical examination were performed. Serum sampling for myoglobin and creatine kinase-MB (CK-MB) was done at the time of presentation (time 0) and 3 hours later (time 3 hours). An echocardiographic study was obtained, and a left ventricular wall motion score was derived.


RESULTS
Using World Health Organization criteria, 21 patients (11.2%) with AMI were identified. The serum markers were found to be clinically and statistically different between AMI and non-AMI groups at both time 0 and time 3 hours. Receiver operator characteristic curves were used to determine a "positive" myoglobin level at 88.7 ng/mL or higher at either time point, and a "positive" CK-MB level at 11.9 ng/mL or higher; these were used as the optimal cutoff values to predict AMI in the ED. Serum myoglobin was a more sensitive marker (90.5%) than CK-MB (81.0%). However, CK-MB was more specific (99.4%) than myoglobin (88.4%). A combination of both tests, which was rated positive if either test was positive, was a superior predictor overall, with a 100% capture rate of AMI patients and a 91.2% specificity. No significant difference in echocardiographic scores was appreciated in the AMI group compared with the non-AMI group (16.9 +/- 1.5 versus 15.3 +/- .5, respectively; P = .3252).


CONCLUSIONS
Serum myoglobin shows greater sensitivity but is less specific than CK-MB in the early detection of AMI. Use of a combination of both rapid assays during a 3-hour time period in the ED appears to be superior to use of either enzyme assay alone. Two-dimensional echocardiography does not appear to be helpful in diagnosing AMI in the ED.
Levitt
M A
MA
Department of Emergency Medicine, Highland General Hospital, Oakland, California, USA.
Promes
S B
SB
Bullock
S
S
Disano
M
M
Young
G P
GP
Gee
G
G
Peaslee
D
D
D000368:Aged; D015415:Biomarkers / Q000097:blood; D003402:Creatine Kinase / Q000097:blood*; D004452:Echocardiography; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D007527:Isoenzymes; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000000981:diagnostic imaging* / Q000201:enzymology; D009211:Myoglobin / Q000097:blood*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013997:Time Factors; D016277:Ventricular Function, Left
D015415:Biomarkers; D007527:Isoenzymes; D009211:Myoglobin; D003402:Creatine Kinase