Tehran University of Medical Sciences The Research in Heart Yield and Translational Medicine (RHYTHM) 3115-7270 21 3 2026 06 28 Establishing the Optimal sST2 Cut-off for Predicting 5-Year All-Cause Mortality in Hospitalized Patients with Heart Failure with Reduced Ejection Fraction 221 230 EN Khanh Nguyen Department of Internal Medicine Ho Chi Minh City, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City Sy Hoang University of Medicine and Pharmacy at Ho Chi Minh City Dung Bui Department of Cardiology, University Medical Center Ho Chi Minh City, Ho Chi Minh City Thang Le DSA Unit, Can Tho S.I.S General Hospital, Can Tho Luan Tran Department of Cardiovascular and Thoracic Surgery, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City 2026 05 19 2026 06 28 Background: Hospitalized patients with chronic heart failure (HF) may experience adverse left ventricular remodeling, systemic and pulmonary congestion, and changes in sST2. Thus, they may require an sST2 cutoff for predicting long-term mortality different from that of patients with stable chronic HF. This study aimed to determine the optimal cutoff value of sST2 predictive of long-term mortality in patients with heart failure with reduced ejection fraction (HFrEF). Methods: This prospective cohort study included 162 hospitalized patients with HFrEF. Plasma sST2 levels were analyzed. Statistical analyses were performed to evaluate the predictive utility of sST2 levels for all-cause mortality and the optimal cutoff value. Results: During follow-up, 99 of 162 patients (61.1%) died. The median admission sST2 concentration was 35.3 [19.1-57.3] ng/mL. The cohort-derived cutoff was >27.1 ng/mL (sensitivity, 89.9%; specificity, 84.1%). Patients above this threshold had a higher hazard of 5-year mortality than those with sST2 <=27.1 ng/mL (HR, 6.27; 95% CI, 3.02-13.05; P<0.001). In the reported multivariable model, each 1-unit increase in ln(sST2) was also associated with mortality (adjusted HR, 7.52; 95% CI, 4.07-13.90; P<0.001). Conclusion: In hospitalized patients with HFrEF, sST2 levels were an independent and associated with 5-year all-cause mortality, and the optimal sST2 cutoff for predicting long-term survival is 27.1 ng/mL. https://rhythm.tums.ac.ir/index.php/jthc/article/view/2474 https://rhythm.tums.ac.ir/index.php/jthc/article/download/2474/1276