The ST2 cardiac biomarker (also known as soluble interleukin 1 receptor-like 1) is a protein biomarker of cardiac stress encoded by the IL1RL1 gene. ST2 signals the presence and severity of adverse cardiac remodeling and tissue fibrosis, which occurs in response to myocardial infarction, acute coronary syndrome, or worsening heart failure. ST2 provides prognostic information that is independent of other cardiac biomarkers such as BNP, NT-proBNP, highly sensitive troponin, GDF-15, and galectin-3. One study indicated that discrimination is independent of age, body mass index, history of heart failure, anemia and impaired kidney function or sex.sST2(Soluble ST2) is a biomarker for risk stratification in patients with heart failure (HF) and prognostic assessment. Compared with BNP and NT-proBNP, ST2 is not affected by age, factors such as BMI and renal insufficiency.Different with so many other heart markers, the level of ST2 varies rapidly with the patient's condition. This means that ST2 can help clinicians respond faster. The increase of sST2 level (> 35ng/ml) was highly correlated with the severity of heart failure which can be used to predict readmission and mortality.