Circulating secretoneurin concentrations predict cardiac arrythmia and mortality in patients with acute tachypnea: data from the akershus cardiac examination 4 study

Background Secretoneurin (SN) is a cardiac biomarker associated with dysfunctional cardiomyocyte Ca2+ handling and risk of mortality in patients with heart failure. Whether circulating SN concentrations are predictive of cardiac arrythmia and mortality in unselected patients admitted with rapid breathing (tachypnea) is unknown. Purpose Assess the associations between SN and cardiac arrythmia and long-term mortality in patients admitted with acute tachypnea and contrast these associations with those of cardiac troponin T (cTnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP). Methods We measured SN, cTnT and NT-proBNP in 556 patients admitted with acute tachypnea to Akershus University Hospital from 2024 to 2025. SN concentrations were measured with a prototype research-use only automated SN chemiluminescence immunoassay. Cause of hospital admission was evaluated by an independent adjudication committee, and patients were grouped as acute heart failure or other causes of admission. We assessed all-cause mortality with follow-up to January 31, 2026 (n = 556). Patients were assessed with Holter Monitoring at baseline (n = 499) and an arrhythmia score was generated based on the severity of the event; premature ventricular complex (PVC) = 1 point, bigeminy = 2 points, couplets = 3 points, or ventricular tachycardia (VT) = 4 points. Associations between biomarkers and all-cause mortality were visualized by Kaplan-Meier plots and quartiles of SN were compared with the log-rank test. We used adjusted Cox proportional hazards regression models to assess the associations between biomarkers and all-cause mortality and adjusted logistic regression models to assess the associations between biomarkers and arrhythmia score ≥ 3. Results The median age was 73.6 (61.4 to 80.0) years and 232 (41.7%) were female. In total, 197 (35.4%) patients were adjudicated with acute heart failure as cause of hospital admission. Concentrations of SN were significantly associated with risk of all-cause mortality (Figure), with comparable effect estimates to those of cTnT and NT-proBNP. The associations of SN with all-cause mortality remained significant in models additionally adjusted for cTnT (p < 0.001) and NT-proBNP (p = 0.002). For cardiac arrythmia, SN provided comparable associations with arrythmia score ≥ 3 to those of cTnT and NT-proBNP (Table). There were no interactions between acute heart failure as cause of hospital admission, biomarkers, and outcomes (all p for interaction > 0.05). Conclusion(s) Circulating SN concentrations provide strong prognostic information for all-cause mortality in patients admitted with acute tachypnea, comparable to the established cardiac biomarkers cTnT and NT-proBNP. SN was associated with high arrhythmia burden, supporting a link between circulating SN concentrations and ventricular arrhythmia in acutely ill patients with tachypnea.