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Background: Circulating secretoneurin (SN) concentrations, as measured by established radioimmunoassay (RIA), risk stratify patients with cardiovascular disease. We now report data for a recently developed research-use-only SN enzyme- linked immunosorbent assay (ELISA) in patients with sus- pected acute coronary syndrome (ACS).
Methods: SN ELISA was developed according to industry standards and tested in 401 unselected chest pain patients. Blood samples were drawn <24 h from admission, and we adjudicated all hospi- talizations as ACS or non-ACS. The mean follow-up was 6.2 years.
Results: SN ELISA with 2 monoclonal sheep anti-SN antibodies has a measuring range of 10–250 pmol/L and demonstrates excellent analytical precision and accuracy across the range of SN concentrations. SN measured by ELI- SA and RIA correlated in the chest pain patients: rho = 0.39, p < 0.001. SN concentrations were higher in ACS patients (n = 161 [40%]) than in non-ACS patients (n = 240) for both assays, with an area under the curve (AUC) of 0.66 (95% CI: 0.61–0.71) for ELISA and 0.59 (0.54–0.65) for RIA. SN concen- trations were also higher in nonsurvivors (n = 65 [16%]) than survivors, with an AUC of 0.72 (0.65–0.79) for ELISA versus 0.64 (0.56–0.72) for RIA, p = 0.007, for difference between as- says. Adjusting for age, sex, blood pressure, previous myo- cardial infarction, atrial fibrillation, and heart failure in mul- tivariable analysis, SN concentrations as measured by ELISA, but not RIA, remained associated with mortality, with a haz- ard ratio of 1.71 (1.03–2.84), p = 0.038.
Conclusions: The nov- el SN ELISA has excellent performance, higher AUC for diag- nosis, and superior prognostic accuracy compared to the es- tablished RIA in chest pain patients.