Diagnostic potential of phosphorylated cardiac troponin I as a sensitive, cardiac-specific marker for early acute coronary syndrome: preliminary report.
BACKGROUND
Cardiac troponin I (cTnI) has low sensitivity in the early hours of acute coronary syndrome (ACS). For patients with early ACS symptoms, we determined the diagnostic potential of an immunoassay for phosphorylated cTnI (PO(4)-cTnI).


METHODS
In a prospective study of 61 emergency department patients with suspected ACS, we compared a novel plasma immunoassay for PO(4)-cTnI to cTnI overall and in a subgroup with symptoms < or =4 h duration (n = 31). Admission PO(4)-cTnI and cTnI assays (thresholds determined by ROC curve) were analyzed in a blinded fashion against the clinical, ECG and coronary angiographic diagnosis of ACS.


RESULTS
Overall, PO(4)-cTnI sensitivity was significantly higher than cTnI (82% vs. 50%, respectively, P < 0.05) and PO(4)-cTnI specificity was 81% (n = 61). Addition of PO(4)-cTnI to cTnI improved sensitivity to 91% vs. 50% for cTnI alone (P < 0.001). In the < or =4 h subgroup (n = 31), PO(4)-cTnI sensitivity was significantly higher than cTnI (79% vs. 26%, respectively, P < 0.01) and PO(4)-cTnI specificity was 75%. In the same < or =4 h subgroup, addition of PO(4)-cTnI to cTnI improved sensitivity to 84% vs. 26% for cTnI alone (P = 0.001).


CONCLUSIONS
The results suggest that PO(4)-cTnI, alone or in combination with cTnI, warrants further investigation as a sensitive, cardiac-specific diagnostic tool for early ACS.
Bar-Or
David
D
Swedish Medical Center, Trauma Research Dept., Englewood, CO 80113, USA. dbaror@dmibio.com
Thomas
Gregory W
GW
Bar-Or
Raphael
R
Rael
Leonard
L
Winkler
James V
JV
D000208:Acute Disease; D015415:Biomarkers; D003327:Coronary Disease / Q000097:blood* / Q000175:diagnosis* / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010766:Phosphorylation; D019210:Troponin I / Q000097:blood* / Q000378:metabolism*
D015415:Biomarkers; D019210:Troponin I