The Critical Diagnostics Presage® ST2 Assay kit is an in vitro diagnostic assay that quantitatively measures ST2 in serum or plasma by enzyme-linked immunosorbant assay (ELISA) in a microtiter plate format.
The Presage® ST2 Assay is indicated to be used in conjunction with clinical evaluation as an aid in assessing the prognosis of patients diagnosed with heart failure.
The Presage® ST2 Controls, Level 1 and Level 2, are designed to be used for verifying the performance of the Critical Diagnostics Presage® ST2 Assay kit.
The assay is calibrated with seven standards spanning the range of 3.1 to 200.0 ng/ml. The standard ST2 analysis cutpoint is 35 ng/ml.
|BC-1065E||Presage® ST2 Assay kit||1 ELISA plate|
|BC-1066E||Presage® ST2 Control Kit||1 vial Low ; 1 vial High|
Some 14 million people in Europe have heart failure and that number is expected to jump to 30 million by 2020.1 More than 10 percent of all Europeans over the age of 65 have heart failure.2
With an aging population, the prevalence of heart failure grows, as does the added burden placed on the healthcare system. The current annual economic cost to treat heart disease in the EU3 exceeds €200 billion, 70% of which is due to hospitalization.4
USING ST2 AS PART OF A HEART FAILURE PATIENT MANAGEMENT PROGRAM
Cardiac biomarkers are substances that are released into the bloodstream when the heart is damaged or stressed. In patients with heart failure, measurement of these biomarkers is used to help risk stratify, to assess treatment options, monitor progress, and guide in-hospital and post-discharge care.
ST2 is one such biomarker. ST2 is a soluble protein expressed by the heart in response to disease or injury. Unlike many other cardiac biomarkers, ST2 levels change quickly in response to changes in the patient’s condition—thus helping physicians make informed decisions on an appropriate course of action to take and, if needed, to quickly adjust treatment.
Numerous published studies have demonstrated that the level of ST2 in blood can best predict patient outcomes. Measuring ST2 via a simple, non-invasive blood test allows for the early identification of high-risk heart failure patients for re-hospitalization and mortality versus those at lower risk.
ST2 BY THE NUMBERS
For instance, chronic heart failure patients with ST2 levels above the standard cutpoint5 have a THREE times greater risk of 30-day rehospitalization or mortality.
As reported in the Merlin study,6 patients who experienced a myocardial infarction and exhibit elevated ST2 levels were FOUR times more likely to develop heart failure within 30 days and at THREE times greater risk of death.
As reported in Socrates et al, acute heart failure patients with ST2 levels above the standard cutpoint are 17 times more likely to be rehospitalized and at THREE times greater risk of death.7
By utilizing Critical Diagnostic’s Presage® ST2 Assay as part of a patient management program, clinicians can be more precise in caring for people with chronic heart failure. This may lead to halting or slowing down the progression of the disease.
While natriuretic peptide markers like BNP and NT-proBNP may help a physician diagnose heart failure in a symptomatic patient, in study after study, ST2 has consistently demonstrated improved accuracy of patient prognosis over peptides markers alone. ST2 also has twice the predictive value of Galectin-3.8
Moreover, ST2 levels are not adversely affected by such confounding factors as age, gender, body mass index, atrial fibrillation, history of heart failure, anemia and impaired renal failure.
And unlike natriuretic peptide markers and Galectin-3, ST2 has a single cutpoint, removing any guesswork, making treatment decisions easier.
USING ST2 TO LOWER HOSPITAL READMISSION RATES
In spite of all the advancements in medicine, over one million Europeans a year end up in hospital for heart failure; half of all heart failure patients will die within four years; and of those diagnosed with severe heart failure, more than half will die within a year of diagnosis.9
The Presage ST2 Assay from Critical Diagnostics allows accurate prognosis and risk stratification of these chronic heart failure patients, which, in turn, provides an essential element to disease management programs, enabling physicians to select those patients who are identified as requiring focused care.
By way of example, published studies have shown that acute heart failure patients with ST2 levels above the standard cutpoint are an alarming 17 times more likely to be rehospitalized and have a three times greater risk of death. Measuring ST2 levels in these patients provides clinically useful information with which to evaluate treatment options.
Using ST2 as part of a patient management program can reduce 30-day rehospitalization rates by 17.3% and also reduce 30-day mortality rates by 17.6%.10
STUDIES SHOW ST2 TO PREDICT HEART FAILURE IN THE FUTURE
Based on recent studies, ST2 was able to predict the development of heart failure and other adverse outcomes in the general population.
The Framingham Heart Study Cohort evaluated over 3,400 “healthy” individuals to determine the prognostic utility of ST2. Study participants were followed for approximately 11 years. ST2 was the most predictive of all biomarkers studied for heart failure or death studied.
As the study authors note, “higher levels of circulating sST211 (comparable to those found in hospitalized patients) can be detected in apparently healthy individuals and precede adverse outcomes.”
In a similar study12 of over 1,800 healthy patients followed for approximately a decade, demonstrated those patients with ST2 levels in the highest quartile, had the highest risk for incident HF and mortality—even after rigorous multivariate adjustment for confounders and other biomarkers.
FREQUENTLY ASKED QUESTIONS
Q: What Is ST2?
A: ST2 is expressed by the heart in response to disease or injury. Unlike many other cardiac biomarkers, ST2 levels change quickly in response to changes in the patient’s condition—thus helping physicians make informed decisions on an appropriate course of action to take and, if needed, to quickly adjust treatment. Critical Diagnostic’s Presage ST2 Assay is a simple blood test that aids in risk assessment of heart failure patients.
Q: I understand that there is a standard cutpoint of 35 ng/ml. If my patient is above or below that cutpoint, what does that tell me?
A: By way of reference, the median normal concentration for ST2 is 18 ng/ml, while concentrations greater than 35 ng/ml are strongly indicative of increased risk of hospitalization or death. Likewise, patients with ST2 levels below the cutpoint are showing improvement and therefore at decreased risk for hospitalization or death..
Q: What clinical studies have been done on ST2?
A: Numerous published studies involving tens of thousands of subjects have demonstrated that the level of ST2 in blood can best predict patient outcomes.
Q: Natriuretic peptides, such as BNP and NTproBNP, are established biomarkers for heart failure. Please explain the additional clinical benefit of ST2?
A: ST2 and natriuretic peptides (NPs) are measures of separate and distinct biological processes. As markers of hemodynamic instability or myocyte stretch NPs are more suitable for diagnosis, however with 25% of patients being rehospitalized within 30 days of discharge, their power for prognosis is insufficient. Study after study has shown that ST2, as a biomarker of disease progression and fibrosis, is the most powerful and clinically useful biomarker for prognosis.
Q: Is ST2 affected by any confounding factors, like the natriuretic peptides are?
A. While NPs have confounding factors that influence levels, including age, gender, high BMI, and impaired renal function. ST2 exhibits none of those confounders, and is thus quite helpful in those grey areas.
Q: What if the NP I’m using is positive, but the ST2 is negative, and vice versa?
A: ST2 and NPs reflect two distinct but overlapping biological pathways, therefore they provide independent and complementary feedback on the disease. As studies have shown, in the case where either NP or ST2 are elevated, it likely that the patient is progressing towards a worsening condition, therefore standard of care coupled with more aggressive treatment may be indicated. We should also add that when the NP and ST2 levels are both low, it’s a strong signal that the patient is improving, and where both are high, the patient is at significant risk for worsening condition or death.
Q: Describe the relationship between ST2 and Galectin-3?
A: Importantly, ST2 gives an early signal for short-term events, functioning as a trigger for initial fibrosis and the cascade of events leading to cardiac remodeling. From published data Galectin-3, on the other hand, is an intrinsic mediator of fibrosis and cardiac remodeling and is thought to reflect a later stage of the disease process. In clinical studies where both biomarkers were tested, ST2 had twice the predictive value of Galectin-3.
Q: How often should a heart failure patient be tested for ST2?
A: There is currently no guideline for frequency of testing. It depends on the severity of the patient’s HF status. We recommend that a HF patient should be tested every time they come in for an outpatient visit, and more often if a patient is in advanced stages of heart failure or hospitalized.
Q: There’s a lot of talk lately about the high rates of rehospitalization of heart failure patients. What role can ST2 play in lowering these readmissions?
A: Of the over one million Europeans that end up in hospital for heart failure each year, an alarming one in four will be re-admitted within 30 days of discharge. The Presage ST2 Assay from Critical Diagnostics, allows accurate prognosis and risk stratification of these patients, which, in turn, provides an essential element to disease management programs that provides physicians with a means of selecting those who are identified as requiring focused care. Using ST2 as part of a patient management program can reduce 30-day rehospitalization rates by 17.3% and also reduce 30-day mortality rates by 17.6%. If you’d like a copy of a white paper report on reducing hospital readmissions, go to our website (www.criticaldiagnostics.com).
Q: I understand that recent studies show that ST2 was able to predict the development of heart failure and other adverse outcomes in the general population.
A. That’s right. The Framingham Heart Study Cohort evaluated over 3,400 “healthy” individuals to determine the prognostic utility of ST2. Study participants were followed for approximately 11 years. ST2 was the most predictive of all markers for heart failure or death studied. In a similar study of over 1,800 healthy patients in Olmstead, MN, followed for approximately a decade, those with ST2 levels in the highest quartile, had the highest risk for incident HF and mortality—even after rigorous multivariate adjustment for confounders and biomarkers.
Heart Failure TODAY is a publication of Critical Diagnostics. This magazine aims to inform you about heart failure and is not intended as medical advice or a substitute for consulting a physician.
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