Background: A new biomarker, suppression of tumorigenicity 2 (ST2) has been introduced as a marker for fibrosis and hypertrophy. Its clinical value in comparison with N-terminal pro-hormone of brain natriuretic peptide /Amino-terminal pro-B-type natriuretic peptide (NTproBNP) in predicting mortality in elderly patients with symptoms of heart failure (HF) is still unclear.
Aim: To evaluate the prognostic value for all-cause- and cardiovascular mortality of ST2 or NTproBNP and the combination of these biomarkers.
Patients and methods: One hundred seventy patients patients with clinical symptoms of HF (77 (45%) were with verified HF) were recruited from one selected primary health care center (PHC) in Sweden and echocardiography was performed in all patients. Blood samples were obtained from 159 patients and stored frozen at -70 °C. NTproBNP was analyzed at a central core laboratory using a clinically available immunoassay.ST2 was analyzed with Critical Diagnostics Presage ST2 ELISA immunoassay.
Results: We studied 159 patients (mean age 77 ± 8.3 years, 70% women). During ten years of follow up 78 patients had died, out of which 50 deaths were for cardiovascular reasons. Continuous NTproBNP and ST2 were both significantly associated with all-cause mortality (1.0001; 1.00001-1.0002, p = 0.04 and 1.03; 1.003-1.06, p = 0.03), NTproBNP but not ST2 remained significant for cardiovascular mortality after adjustments (1.0001; 1.00001-1.0002, p = 0.03 and 1.01; 0.77-1.06, p = 0.53), respectively. NTproBNP above median (>328 ng/L) compared to below median was significantly associated with all-cause mortality(HR: 4.0; CI :2.46-6.61; p < 0.001) and cardiovascular mortality (HR: 6.1; CI: 3.11-11.95; p < 0.001). Corresponding analysis for ST2 above median (25.6 ng/L) was not significantly associated neither with all-cause mortality (HR; 1.4; CI: 0.89-2.77) nor cardiovascular mortality (HR: 1.3; CI: 0.73-2.23) and no significant interaction of NTproBNP and ST2 (OR: 1.1; CI: 0.42-3.12) was found.
Conclusion: In elderly patients with symptoms of heart failure ST2 was not superior to NTproBNP to predict all cause or cardiovascular mortality. Furthermore, it is unclear if the combination of ST2 and NTproBNP will improve long-term prognostication beyond what is achieved by NTproBNP alone.
Keywords: NTproBNP; ST2; elderly; heart failure; morbidity; mortality.