CHICAGO -- Two new studies add to the rapidly growing body of evidence that inflammation in the bloodstream can be a powerful predictor of heart disease.
The findings could help explain why people with no known risk factors such as high cholesterol or high blood pressure can still have heart attacks.
One study found that levels of an enzyme called MPO were elevated in people who had had heart attacks, heart bypass surgery and narrowed coronary arteries. The other study linked a different substance, interleukin 6, to an increased risk of death in heart patients. Both sutrstances are associated with inflammation.
An accompanying editorial in Wednesday's Journal of the American Medical Association said it is premature to suggest routine testing for MPO or interleukin 6.
In recent years, doctors have come to suspect that smoldering inflammation whether triggered by an infection or some other condition--can damage the walls of heart arteries, making them more prone to the fatty buildups that can lead to heart attacks.
One of the two studies found that patients with the highest levels of MPO, or myeloperoxidase, which is normally found in infection-fighting white blood cells, had a 20-fold greater risk of heart disease man those with the lowest levels.
High levels were even found in people with no significant heart disease and with no risk factors such as high cholesterol and high blood pressure.
Cleveland Clinic researchers said that may help explain why heart attacks frequently occur in people previously thought to be healthy.
"What is most exciting is that this marker appears to be significantly better at predicting risk for atherosclerosis, or hardening of the arteries, than blood tests now used," including cho lesterol tests, said Dr. Stanley Hazen, who coordinated the research. He noted that about 50 percent of heart attack patients have normal cholesterol levels.
It is uncertain what caused the elevated MPO levels in some of the 333 patients studied, though Hazen said he...