Abstract 13412: Use of a Novel Single Molecule Ultra Sensitive cTnI Assay as an Early Rule Out Marker for NSTEMI: The WESTCOR Study.

Introduction: Early rule out of NSTEMI is essential in patients presenting with chest pain. Hypothesis: A novel ultra-sensitive (us) troponin (cTn) assay might have higher diagnostic accuracy compared to high sensitive (hs) cTnT and cTnI assays for early identification of NSTEMI in unselected patients presenting with acute chest pain. Methods: 979 patients admitted to Haukeland University Hospital (Norway) with suspected NSTE-ACS were consecutively included from September 2015 to February 2017. The final diagnosis was adjudicated by two independent cardiologists based on all available clinical, laboratory (i.e. hs-cTnT (Roche Diagnostics)) and imaging data. The samples taken at admission were biobanked and later on also measured for hs-cTnI (Abbott Diagnostics) and a novel ultra sensitive cTnI assay (Singulex Inc. (Sgx)). The following cut off values (i.e. baseline samples taken at admission) was tested for safe rule out of NSTEMI: < 2 ng/L (us-cTnIsgx), < 2 ng/L (hs-cTnIAbbott) and < 5 ng/L (hs-cTnT). The negative predictive value (NPV) for NSTEMI using these cut off values, and the AUC-ROC (Delong test) were compared between the us-cTnIsgx, hs-cTnIAbbott and hs-cTnT assays. Results: The prevalence of NSTEMI was 13%, unstable angina pectoris 11%, non-ACS cardiac disease 8%, non-cardiac chest pain 58% and other diseases 10%. Cardiac troponins were measurable in the baseline sample for 99.9% (us-cTnIsgx), 87% (hs-cTnIAbbott) and 70% (hs-cTnT) of the total cohort, respectively. When we applied the cut off values for rule out as stated above were 0.8% (us-cTnIsgx), 2.3% (hs-cTnIAbbott) and 1.5% (hs-cTnT) of NSTEMI patients incorrectly ruled out. The same cut off values would correctly rule out 51% (us-cTnIsgx), 33% (hs-cTnIAbbott) and 43% (hs-cTnT) of patients with non-cardiac chest pain. The NPV for NSTEMI were 99.7% (us-cTnIsgx), 98.6% (hs-cTnIAbbott) and 99.3% (hs-cTnT). The ROC-AUCs for baseline samples were significantly higher (p value < 0.01) for us-cTnIsgx (AUC 0.95) compared to hs-cTnIAbbott (AUC 0.93) and hs-cTnT (AUC 0.91). Conclusion: The us-cTnIsgx assay showed significant higher diagnostic performance for early rule out of NSTEMI, compared to two commonly used high sensitive troponin assays. [ABSTRACT FROM AUTHOR]