BACKGROUND: High-throughput assays are required for novel biomarkers to have clinical potential. Secretoneurin (SN) is a candidate biomarker, and the performance of a new high-throughput SN assay is not known. METHODS: We measured SN concentrations with a prototype chemiluminescent immunoassay (CLIA) in 299 patients hospitalized with acute dyspnea. We compared the results with a CE-marked SN enzyme linked immunosorbent assay (ELISA). We adjudicated the cause of dyspnea as heart failure (HF) or non-HF, and we obtained information on all-cause mortality during follow-up. RESULTS: SN concentrations measured with CLIA and ELISA were closely correlated: rho = 0.81, P <
0.001. SN CLIA concentrations were higher in HF patients (n = 129) compared to patients with non-HF-related dyspnea (n = 170): median 51 (quartile 1-3 40-69) vs 41 (32-54) pmol/L, P <
0.001. The area under the curve (AUC) of SN CLIA to diagnose HF was 0.64 (95% CI, 0.58-0.71) and the AUC of N-terminal pro-B-type natriuretic peptide (NT-proBNP) was 0.85 (0.81-0.89). During median 818 days follow-up, 110 patients died (37%). There was a nonlinear association between SN CLIA concentrations and mortality with optimal cutpoint 53 pmol/L. SN CLIA concentrations >
53 pmol/L were associated with mortality after adjusting for clinical variables and NT-proBNP and cardiac troponin T concentrations: hazard ratio 1.7 (95% CI, 1.1-2.7), AUC 0.67 (0.61-0.74). We found similar results for SN ELISA for diagnosis and prognosis with AUC 0.63 (0.57-0.70) for the prediction of mortality. CONCLUSION: The high-throughput SN CLIA correlates with the SN ELISA and provides independent prognostic information over established biomarkers in patients with acute dyspnea.