CK-MB Activity, Any Additional Benefit to Negative
Troponin in Evaluating Patients with Suspected Acute
Myocardial Infarction in the Emergency Department
Veeravich Jaruvongvanich MD*,
Weeranuch Rattanadech MD**, Wilawan Damkerngsuntorn MD*,
Suthinee Jaruvongvanich MD*, Yongkasem Vorasettakarnkij MD***,****
Affiliation :
* Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
** Division of Oncology, Department of Internal Medicine, Faculty of Medicine, Mahidol University, Bangkok, Thailand
*** Division of Hospital and Ambulatory Medicine, Department of Medicine, Faculty of Medicine,
Chulalongkorn University, Bangkok, Thailand
**** Cardiac Center, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
Background : Coronary heart disease is now the leading cause of death. Diagnosing myocardial infraction (MI) needs
cardiac marker in case of equivocal clinical presentations and EKG interpretations. Troponin yields high sensitivity and
specificity and could be used as a single screening assay. However, in actual practice, clinicians send CK-MB activity
(CKMBa) as a combined marker with an expectation of providing additional diagnostic value due to large historical data.
Discordant results from both markers lead to unclear management. Our study was to determine whether CKMBa has
potential benefit for initial screening of MI in addition to cardiac troponin T (cTpT) in the Emergency Department (ED),
and can this marker be safely removed from the routine laboratory panel in the emergency setting in Thailand.
Material and Method: We conducted a retrospective cohort single-center study to examine the usefulness of CKMBa in the
ED from 907 patients who presented with clinically suspected acute MI, and investigated with both biomarkers (CKMBa
and cTpT). In these patients, 97 patients were included in the final analysis as they had negative cTpT associated with
positive CKMBa or CKMBa turned to be positive within 24 hours after serial biomarkers measurements. The outcome was
assessed by the final diagnosis, the cause of death if patients died during admission, and the 180-day mortality from medical
chart review. In patients highly suspected for MI, further investigations were done including echocardiogram, exercise stress
test, and coronary angiogram by experienced cardiologists.
Results : During the study period, cTpT were sent 1,772 times and most (95.2%) of the samples were associated with CKMBa
results. The outcome showed that no one with negative cTpT was diagnosed as MI on a discharge diagnosis. Fourteen
patients died during admission. The definitive cause was not defined as MI. The 180-day mortality was zero. During the
follow-up, there was no MI suspected issues that needed further cardiac evaluations. The positive predictive value of CKMBa
with negative cTpT was 0% (95% CI, 0-0.047).
Conclusion : CKMBa added no benefit to cTpT in diagnosing acute MI in ED. Removing CKMBa from emergency panel
could be considered.
Keywords : Troponin, CK-MB activity, Myocardial infarction, Emergency department
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