Clinical application and new utility of sST2 in emergency area

In the emergency field, many biomarkers are evaluated for clinical management of several acute diseases in clinical practice, to precise diagnosis, risk stratification or response to specific treatment. The protein ST2 is involved in inflammatory conditions, fibroproliferative diseases, autoimmune diseases, trauma, sepsis, and most recently in pulmonary and cardiovascular diseases. Higher levels of serum ST2 (sST2) are associated with inflammatory responses in several conditions. Whereas pro-BNP is considered the gold standard marker for the diagnosis of acute heart failure (HF), several studies observed that sST2 shows additional diagnostic and prognostic value; for example, this biomarker has stronger power to predict fatal events in HF in preserved or reduced ejection fraction, especially with values ≥35 ng/mL. Moreover, sST2 is useful to identify the degree of coronary artery stenosis and to predict the development of adverse events 1-year after coronary revascularization due to acute coronary syndrome (ACS). In fact, levels of sST2>35 ng/mL are associated with higher Gensini scores, multivessel disease and higher rate of major cardiovascular and cerebrovascular events. Recently, during acute COVID-19 infection, higher levels of sST2 showed role as an inflammation marker, associated with worse outcomes (i.e., ICU admission, mechanical ventilation, or in-hospital death). Although the role as prognostic marker is well highlighted in cardiovascular diseases and heart failure, sST2 can be evaluated in different conditions characterized by considerable impact in the field of emergency, giving useful information in terms of greater diagnostic accuracy, risk stratification, and prognosis.