Early verification of myocardial ischemia with a novel biomarker of acute tissue damage: C-reactive protein fractional forms.
BACKGROUND
We evaluated the utility of an independent biomarker of early ischemic cellular damage-circulating fractional forms of C-reactive protein (fracCRP), to verify the diagnostic relevance of low Troponin I (TnI) values within the context of a workup for Acute Coronary Syndrome (ACS).


METHODS
On a semi-preparative scale, the molecular characteristics of fracCRP were established by electron microscopy and Western Blot, using isolates captured from patient serum on phosphorylcholine beads and purified by size exclusion high-pressure liquid chromatography (SE-HPLC). Captured on an analytical scale, the diagnostic utility of fracCRP was evaluated in first-draw plasma specimens (total CRP not exceeding 6 mg/l) recovered from 300 cardiac emergency patients with final discharge diagnoses of ACS ruled out (N=132) or ruled in (N=168).


RESULTS
At a cutoff value chosen for 97.7% test specificity, the test metric (fracCRP×TnI) identified in the first blood draw 39.9% of all emergency patients ultimately diagnosed with ACS, and 17.9% of ultimately diagnosed patients who arrived with TnI values within the normal reference range (0.01-0.04 ng/ml).


CONCLUSIONS
These findings suggest that the fracCRP test metric could serve as a rule-in test for ACS in a significant proportion of low to moderate risk emergency patients.
Department of Hospital Laboratories, UMass Memorial Medical Center, One Biotech Park, 365 Plantation Street, Worcester, MA 01605, USA. charles.kiefer@umassmemorial.org
Charles R
CR
Kiefer
Rachel E
RE
Stock
Sharon S
SS
Flanagan
Chad E
CE
Darling
Craig S
CS
Smith
L Michael
LM
Snyder
D054058:Acute Coronary Syndrome / Q000097:blood* / Q000175:diagnosis; D015415:Biomarkers / Q000097:blood; D015153:Blotting, Western; D002097:C-Reactive Protein / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D017202:Myocardial Ischemia / Q000097:blood* / Q000175:diagnosis; D020033:Protein Isoforms / Q000097:blood; D021122:Protein Subunits / Q000097:blood*; D012016:Reference Values; D012680:Sensitivity and Specificity; D019210:Troponin I / Q000097:blood*
D015415:Biomarkers; D020033:Protein Isoforms; D021122:Protein Subunits; D019210:Troponin I; D002097:C-Reactive Protein