New Tests Measure Heart Risk
Inflammation-related enzymes the target
WEDNESDAY, Oct. 22, 2003 (HealthDayNews) -- Two tests that look at molecular markers of inflammation hold promise for singling out people at high risk of heart attacks and other cardiovascular problems, research teams in the United States and Germany report.
In the United States, researchers at the Cleveland Clinic Foundation used a test that measures levels of myeloperoxidase, an enzyme that fosters the inflammatory process that can cause a fatty deposit in an artery to burst, blocking the artery and causing a heart attack.
In Germany, researchers at Gutenberg University in Mainz measured levels of glutathione peroxidase 1, which works to prevent dangerous inflammatory events.
High levels of myeloperoxidase or low levels of glutathione peroxidase 1 signal danger, say separate reports in the Oct. 23 issue of the New England Journal of Medicine.
The two trials were done in very different settings. The German researchers tried their test on 636 people with suspected coronary artery disease. The incidence of heart attacks or other major problems in the 25 percent of patients with the highest blood levels of glutathione peroxidase 1 was two-thirds lower than for those with the lowest levels, the journal report says.
In addition to helping predict risk, "increasing glutathione peroxidase 1 activity might lower the risk of cardiovascular events," the report says.
The myeloperoxidase test was done on 604 people who came to the Cleveland Clinic emergency room with chest pains indicating possible heart attacks.
"Most people who present to the emergency room aren't having heart attacks," explains study leader Dr. Stanley L. Hazen, head of preventive cardiology at the Cleveland Clinic. The usual approach is to perform an electrocardiogram and do blood tests for the enzymes that show heart damage, Hazen says.
But those tests often are not conclusive, so more extensive tests must be done. Adding the myeloperoxidase test to the usual blood test successfully identified 90 percent of the patients who were indeed having heart attacks, he says.
And the test had added, longer-term value for patients who weren't having heart attacks, Hazen says. Those with elevated myeloperoxidase levels were found to be at high risk for having a heart attack or other major problem in the next three to six months and required special attention, he says.
Hazen sees a time when the myeloperoxidase test will be part of the routine for emergency room diagnosis of heart attacks. It is "an exceptionally easy test" to perform, he says, and his group is working with commercial laboratories to develop a kit for approval by the U.S. Food and Drug Administration.
"We do have ongoing research studies where we are using it, to try to speed its introduction," Hazen says.
But Dr. Teri Manolio, director of epidemiology and biometry at the National Heart, Lung, and Blood Institute, takes a cautious attitude in an accompanying editorial.
"Crossing the boundary from research to clinical application requires a lot of work," Manolio says. "This work needs to be validated and replicated in many other patients."
For now, the best use of the new tests would be to identify people who will benefit most from control of well-known risk factors such as high blood pressure and cholesterol, she says.