DALLAS, May 18 -- Two proteins that carry cholesterol in the blood may provide a better way to measure heart attack risk than the usual cholesterol blood test, report researchers in today's Circulation: Journal of the American Heart Association.
"Because the two proteins are more sensitive heart disease risk detectors than cholesterol, they may identify more individuals at risk and one day replace cholesterol testing," says the study's lead author, Arthur J. Moss, M.D., professor of medicine (cardiology) at the University of Rochester Medical Center, Rochester, N.Y.
The association between the proteins -- apolipoprotein (apo) A-1 and apolipoprotein (apo) B -- and heart attack risk held true even in the presence of heart disease risk factors including, smoking, diabetes, high blood pressure and high blood levels of cholesterol.
(Apo) A-1 and apo B carry cholesterol in the bloodstream. Apo B is a cholesterol donor, while apo A-1 is a cholesterol scavenger.
Researchers also identified a third protein, D-dimer, which was associated with heart attack risk. D-dimer is a breakdown product in the blood when clots form. Elevated levels of D-dimer indicate excess clotting or coagulation activity in the blood.
Individuals with the blood protein profile of low apo A-1, high apo B, and high D-dimer levels were eight times more likely than others in the study to experience a second heart attack within two years, Moss says. Patients with an abnormal blood level of only one of these proteins were twice as likely to experience another heart attack within two years.
When apo B levels are high, apo B deposits cholesterol on the inside surface of
the plaque. Then it moves into the plaque, thereby increasing the size of the
fatty deposit. Ordinarily, apo A-1 would pick up these cholesterol deposits
before they enter the plaque. However, if apo A-1 levels are low, the process
does not go as expected. Instead, the cholesterol accumulates and for
Contact: Carole Bullock
American Heart Association