A study published July 7, 2005 in the New England Journal of Medicine offers hope of earlier and less-invasive detection of dangerous blockage in the coronary arteries due to atherosclerosis. The study by Tsimikas et al. was done to see if measuring the amount of lipoprotein (a) [Lp (a), a modified form of low density lipoprotein (LDL)] or certain modified fats — [oxidized LDLs] — in a blood sample would correlate with the presence and extent of obstructive disease in the coronary arteries. An editorial in the same issue of the journal says the evidence is growing that oxidized phospholipids are involved in the buildup of fatty deposits in the arteries — plaques that can kick off a heart attack or stroke — and that this is the first study to establish a relationship between the level of these lipids in the blood and the risk of coronary artery disease.

The researchers obtained blood samples from 504 symptomatic individuals immediately before each had an exploratory coronary angiogram. Using a monoclonal antibody test called OxLDL-E06, the researchers measured the amount of oxidized phospholipids per particle of apolipoprotein B-100 in the blood. They compared their data to the angiogram results and found that the blood test correlated with the presence and extent of obstructive disease (a blockage of more than 50% of an artery’s diameter). Having hypercholesterolemia plus increased levels of either substance — the oxidized phospholipid or the Lp(a) lipoprotein — greatly increased the odds of coronary artery disease, the study found, and having increased levels of both correlated with a greater likelihood of coronary artery disease, particularly among those younger than age 60.

A collaboration between the University of California San Diego School of Medicine, Mayo Clinic, and Duke University, the study concluded that “plasma levels of oxidized phospholipids present on apoB-100-containing lipoproteins and predominantly on Lp(a) lipoprotein reflect the presence and extent of angiographically documented coronary artery disease” and suggested further study to “explore these mechanisms and to determine whether these measures of oxidation predict clinical events.”

Some form of a test measuring oxidized LDL or oxidized phospholipids in the blood may eventually complement current cholesterol and lipid tests, helping to identify individuals with advanced atherosclerosis or even those with earlier stages of the disease. As the role of these oxidized lipids in atherosclerosis becomes better understood, scientists may even learn how to design a therapy that targets these lipids and helps ward off heart attacks and strokes. Meanwhile, researchers continue their work to understand the process of plaque buildup in the arteries, the chronic inflammation and cell death that develops, and the life-impairing, life-threatening clots that develop and can cause a heart attack.

Sources
Berliner JA. A role for oxidized phospholipids in atherosclerosis. N Engl J Med 2005;353:9-11.

Tsimikas S, Brilakis ES, Miller ER, et al. Oxidized phospholipids, Lp(a) lipoprotein, and coronary artery disease. N Engl J Med 2005; 353:46-57.