The Critical Diagnostics Presage® ST2 Assay has been FDA cleared for use in conjunction with clinical evaluation as an aid in assessing the prognosis of patients diagnosed with chronic heart failure. The Assay quantitatively measures ST2 in serum or plasma by enzyme-linked immunosorbant assay (ELISA) in a microtiter plate format.
Heart failure is a chronic, progressive condition in which the heart is unable to provide the needed blood volume to support critical body functions. As the heart fails, the pumping volume is reduced leading to organ damage and fluid accumulation in the lungs and extremities. Individuals with heart failure require extensive healthcare management and as they advance with disease have a high rate of healthcare burden, hospitalization and death globally. Improved prognosis and risk stratification of individual heart failure patients may facilitate enhanced clinical management of these patients.
The protein ST2 (suppressor of tumorigenicity 2) is a member of the interleukin-1 receptor family. ST2 is expressed as two isoforms generated by alternative promoter splicing and 3’ processing. One isoform is a membrane bound version (ST2L) that functions as a receptor for IL-33, whereas the other isoform is a soluble form (sST2) that functions as a decoy receptor by binding IL-33 and preventing ST2L signaling. Both ST2 and IL-33 function as “alarmins” that alert the immune system to cellular damage. Cardiac stress has been shown to result in an upregulation and release of ST2 and IL-33 [1,2]. IL-33 signaling has been shown to be cardioprotective, whereas sST2 blocks IL-33 signaling thereby reducing the cardioprotective function of IL-33. Elevated levels of sST2 are thought to block the cardioprotective signal of IL-33 and lead to increased stress on the heart, resulting in tissue fibrosis and disease progression . Thereby, sST2 levels can provide a measure that aids in the prognosis of patients diagnosed with heart failure, as evidenced in the Presage® ST2 assay findings in the HF-ACTION cohort [4,5].
The Presage® ST2 assay provided by ProterixBio is a 510(k) cleared device  providing a quantitative measure of soluble ST2 in serum or plasma (K3EDTA and Heparin). The assay cutoff of 35ng/mL was established between the 90th and 95th percentile of a reference cohort self-declared as healthy with no history of heart disease. sST2 levels greater than 35ng/mL are demonstrated to be predictive of increased risk for Cardiovascular Disease hospitalization and mortality and all cause hospitalization and mortality within the referenced study period (4 years). sST2 levels have demonstrated value, in conjunction with clinical evaluation, as an aid in the prognosis of patients diagnosed with chronic heart failure. And, more recently, sST2 levels have demonstrated independent prognostic value in a large prospective clinical trial aimed at treatment, ARNI compared to ACEI, with improved outcomes in patients with heart failure a reduced ejection fraction, the PARADIGM-HF Trial .
The Presage® ST2 Assay is intended to be used only in patients with chronic heart failure and should not be used for diagnosis of heart failure.