Survival among hospital in-patients with troponin T elevation below levels defining myocardial infarction.
BACKGROUND
Cardiac troponin T (cTnT) has an accepted place in the management of patients presenting with suspected acute coronary syndrome (ACS). Uncertainty remains about the significance and interpretation of elevated cTnT below the cut-off levels defining myocardial infarction (0.1 microg/l).


OBJECTIVE
To compare the mortality risks for elevation of cTnT in the ranges 0.01-0.029 microg/l, 0.03-0.099 microg/l and <0.01 microg/l.


METHODS
Retrospective record study in three hospitals.


METHODS
All cTnT measurements with values in the range >0.01-0.099 microg/l analysed during January 2002 were extracted from clinical biochemistry laboratory databases. Following agreed exclusion criteria, 179 patients with cTnT in the range 0.01-0.099 microg/l and 60 patients <0.01 microg/l were selected at random from across the three sites. Six-month follow-up was completed by review of case notes and contact with the patients' GP.


RESULTS
There was a graded increase in mortality with increasing cTnT, although only achieving statistical significance for patients in the 0.03-0.099 microg/l range. The graded increase in relative risk with cTnT was weaker after adjustment for potential confounding factors


CONCLUSIONS
We found a trend for worse survival with increasing cTnT within the range 0.01-0.099 microg/l in unselected patient populations presenting with possible acute coronary syndrome. This suggests that the combined effects of assay imprecision and co-morbidity should be taken into account when interpreting borderline elevation of cTnT. The use of a cut-off based on current standards of assay precision should be used to define the sensitivity of cTnT as biochemical evidence of ischaemic cardiac damage and as an indicator of mortality risk. This level is likely to be between 0.03 and 0.1 microg/l.
Cook
G
G
Consultant in Public Health Medicine, The Willows, Stepping Hill Hospital, Stockport NHS Trust, Poplar Grove, Stockport SK2 7JE, UK. gary.cook@stockport-tr.nwest.nhs.uk
Taylor
D
D
France
M
M
Burrows
G
G
Manning
E
E
Lyratzopoulos
G
G
McElduff
P
P
Lewis
P
P
Martin
M
M
Heller
R F
RF
D000368:Aged; D015415:Biomarkers / Q000032:analysis; D002637:Chest Pain / Q000378:metabolism; D003404:Creatinine / Q000097:blood; D005260:Female; D006331:Heart Diseases / Q000378:metabolism; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood; D012189:Retrospective Studies; D012307:Risk Factors; D016019:Survival Analysis; D020107:Troponin T / Q000032:analysis*
D015415:Biomarkers; D020107:Troponin T; D003404:Creatinine