Test to Predict Cardiovascular Risk In Heart Attack Patients Not Yet Appropriately Used
Heart Attack Test
A new brain chemical test that predicts which patients with heart attack symptoms are at higher risk of dying is paradoxically not being used in younger, healthier patients who could benefit the most from the prognostic information provided by this test, according to a new analysis by cardiologists at the Duke Clinical Research Institute (DCRI).
While previous studies have shown that elevated levels of "brain natriuretic peptide" (BNP) in the blood are associated with higher risks of death in heart attack patients, researchers know little about how this new test is actually being used in U.S. hospitals to risk stratify patients with heart attacks.
Natriuretic peptides are produced by the brain and heart tissue where there is hemodynamic stress on the heart as a signal to the kidneys to produce more urine, which in turn reduces the volume of blood fluid, facilitating damaged or weakened heart muscle to pump blood throughout the body. Larger elevations of BNP levels have been previously shown to be associated with an incremental increase in the risk of mortality for heart attack patients.
In their analysis, the researchers found that the BNP test was performed mainly on patients who already had many high-risk clinical factors, such as history of congestive heart failure, older age and diabetes. However, the researchers discovered, younger and seemingly healthier patients with elevated BNP levels were actually at a two to four times greater risk of dying in the hospital than the high-risk patients with elevated BNP levels.
"Among all the patients in our analysis who had BNP levels measured, incremental increases in BNP levels were associated with higher risks of in-hospital death," said DCRI cardiologist Matthew Roe, M.D., who presented the results of his analysis March 14, 2006, during the 55th annual scientific sessions of the American College of Cardiology (ACC) in Atlanta.
"However, the mortality risks associated with higher BNP levels were greater among sub-groups of patients who were less likely to have BNP levels measured at all," Roe continued. "It appears that physicians were ordering tests for those patients who would already be considered at the highest risk of early mortality, such as those with congestive heart failure on hospital presentation. More randomized trials are needed to specifically identify those patients who should be tested and those who would benefit the most from this new test."
To understand more clearly how the BNP test is used in the U.S., Roe and his colleagues consulted the national quality improvement initiative known as CRUSADE, which stands for "Can Rapid risk stratification of UnStable Angina patients suppress aDverse outcomes with Early implementation of the ACC/American Heart Association (AHA) guidelines."
CRUSADE continuously gathers data from participating hospitals that treat patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS)