Lack of concordance between a rapid bedside and conventional laboratory method of cardiac troponin testing: impact on risk stratification of patients suspected of acute coronary syndrome.
OBJECTIVE
This study was designed to test the usefulness of a bedside assay as compared to a laboratory method of troponin testing to predict adverse cardiac outcome of chest pain patients.


METHODS
We studied 358 ER visits of patients suspected of a non ST-elevation acute coronary syndrome. cTnI (Immulite, DPC) on a lab analyser and cTnT (Cardiac Reader, Roche) at bedside were measured at baseline. The between-assay level of concordance, reporting turnaround times and clinical outcomes during 180 days of follow-up were assessed. Death and myocardial infarction were then evaluated according to troponin result, either concordant negative, discordant or concordant positive.


RESULTS
Discordance occurred in 11.4% (41/358) of cases. The proportion of patients with a positive cTnI and negative cTnT result (8.9%) versus the reverse (2.5%) differed significantly (p<0.001). The median time gained using the rapid test was 72 min. The rate of death and/or MI was 25% (10/40) among patients with discordant results as compared to 7.5% (17/228) with a concordant negative result (p<0.001). All patients from the discordant group with an event had a positive cTnI result, while cTnT was negative.


CONCLUSIONS
Patients with a discordant reading were at high risk of adverse cardiac outcome, which was only identified by the laboratory cTnI assay. Markedly, the use of the rapid assay saved time at the expense of clinical sensitivity.
Cramer
G Etienne
GE
Heartcentre, Radboud University Nijmegen Medical Centre, The Netherlands. g.cramer@cardio.umcn.nl
Kievit
Peter C
PC
Brouwer
Marc A
MA
de Keijzer
Marinus H
MH
Luijten
Hans E
HE
Verheugt
Freek W A
FW
D000368:Aged; D019411:Clinical Laboratory Techniques; D003327:Coronary Disease / Q000097:blood* / Q000175:diagnosis*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D019095:Point-of-Care Systems; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D018570:Risk Assessment; D016896:Treatment Outcome; D020107:Troponin T / Q000097:blood*
D020107:Troponin T