Clinical relevance of sST2 in cardiac diseases.

ST2 has two main isoforms, ST2L and soluble isoform of ST2 (sST2), by alternative splicing. The interaction between interleukin (IL)-33 and the transmembrane isoform ST2L is up-regulated in response to myocardial stress and exerts cardio-protective actions in the myocardium by reducing fibrosis, hypertrophy and enhancing survival. The circulating isoform sST2, by sequestering IL-33, abrogates these favorable actions and will be elevated as a maladaptive response to cardiac diseases. Indeed, circulating sST2 concentrations correlate with a worse phenotype of disease including adverse remodeling and fibrosis, cardiac dysfunction, impaired hemodynamics and higher risk of progression. In patients with acute and chronic heart failure, sST2 concentrations are strongly predictive of death, regardless of the cause and left ventricle (LV) ejection fraction, and contribute relevant information in addition to other prognosticators and biomarkers, as natriuretic peptides or troponins. sST2 also retains prognostic information in the setting of acute myocardial infarction (AMI) and predicts cardiovascular death and risk of heart failure (HF) development in these patients. sST2 could also be a promising tool to stratify the risk of sudden cardiac death (SCD) in patients with depressed LV ejection fraction. Therefore, sST2 represents a clinically relevant biomarker reflecting pathophysiological processes and contributing predictive information in the setting of several cardiovascular diseases, and especially in patients with HF.