Promising New Cardiovascular Biomarker
In published research, ST2 has been shown to be a novel biomarker of neurohormonal and biomechanical stress activation in patients with heart failure or ACS^5,6,7.

When the heart tissue is mechanically stressed, due to disease or injury, one of the responses is expression of the protein ST2. This protein can be measured in human plasma samples using a simple laboratory test.  More recent research measuring ST2 levels in patient samples has shown that ST2 may provide diagnostic and prognostic value beyond that available from existing laboratory assays.

In a key published study of patients with severe chronic NYHA class III to IV heart failure, changes in ST2 were shown to be a significant predictor of mortality or transplantation independent of both BNP and ProANP. The change in ST2 over a two-week period was predictive of ultimate adverse outcome, whereas change in BNP over this same period was not⁵.

ST2 Has Potential Value in Aiding Both Diagnosis and Prognosis
However, the greatest potential value of ST2 identified to date, is its power in predicting the outcome of patients either presenting with symptoms of heart failure or diagnosed with heart failure. In a key study of patients presenting to the emergency department with shortness of breath, patients who had an ST2 value below the threshold had a mortality event rate less than 2% within one year of discharge from the hospital, whereas those patients with an ST2 value above the threshold had a 28% mortality event rate within one year⁸.

The most dramatic results were achieved by looking at 90-day mortality prediction. In this cohort there were 40 mortality events within 90 days. Of these 40 patients 39 had an ST2 value above the threshold, the one patient with an ST2 value below the threshold died at day 57. By comparison there were nine patients who suffered a mortality event within 90 days that had NT-proBNP values below the threshold.

A further study has shown that the percent change in ST2 during hospitalization is also predictive of mortality within 90 days. Patients whose ST2 level decreased by 16% during hospitalization had a 93% chance of surviving, while those patients whose ST2 concentration did not decrease by this amount had a 33% chance of suffering a mortality event within 90 days. This prognostic capability was further enhanced by multiplexing ST2 values with currently used laboratory measurements, such as BNP, NT-proBNP, BUN or other indications of renal function. This initial data indicates that ST2 may be a powerful biomarker for prediction of near term mortality in heart failure patients and also suggests that ST2 may be a useful biomarker for monitoring treatment regimes and selecting alternate approaches based on changes in ST2.

⁵Weinberg E, Shimpo M, Gilles DK, et. al. Expression and Regulation of ST2, an Interleukin-1 Receptor Family Member, in Cardiomyocytes and Myocardial Infarction. Circulation. 2002;106:2961-2966.
⁶Weinberg E, Shimpo M, Hurwitz, et. al. Identification of Serum Soluble ST2 Receptor as a Novel Heart Failure Biomarker. Circulation. 2003;107:721-726.
⁷Shimpo M, Morrow D, Weinberg E, et. al. Serum Levels of the Interleukin-1 Receptor Family Member ST2 Predict Mortality and Clinical Outcome in Acute Myocardial Infarction. Circulation. 2004;109:2186-2190.
⁸Januzzi, J, Presented at the 2007 American Heart Association Annual Meeting.

Presage and assays employing ST2 are not currently approved by the FDA for clinical use and are not available for sale in the US for clinical use.