Blood Protein Offers Clues To Heart Attack In Healthy People

We've all wondered how a seemingly healthy person can actually be at high risk for heart disease or a heart attack. Now researchers have uncovered a new clue to this mystery. The culprit: myeloperoxidase (MPO), a protein secreted by white blood cells that both signals inflammation and releases a bleach-like substance that damages the cardiovascular system.

Although MPO is intended to kill harmful bacteria, it may instead inflame the body's arteries and cripple protective substances in the blood, according to a study published in the July 10, 2007, issue of the Journal of the American College of Cardiology (JACC). As a result, long before conventional risk factors set off alarms, elevated MPO levels signal that harmful plaque has been building up.

"Another interesting aspect of MPO is that it may be a marker for unstable plaque. Even more than the number or severity of coronary plaques, we want to know the risk of plaque rupture, and this evolving new marker may help in that regard. More study is needed, but among the hundreds of markers tested to date, MPO looks like a "keeper" that will one day become part of clinical care," Dr. Cannon said.