Knowing your cholesterol number may not be enough in the future to protect you from coronary heart disease. Recent studies suggest specific blood proteins may be more sensitive predictors of this major killer.
Now, Dr. Peter Kwiterovich, chief of the Johns Hopkins Medical School's atherosclerosis clinic, has shown that in women, the Apo B blood protein level is a better predictor of the disease than the Apo A-1 level, while the opposite is true of men.
Kwiterovich reported on his research yesterday at an American Heart Association scientific session in Anaheim, Calif..
He headed a Hopkins team that studied 99 men aged 50 or younger and 104 women 60 or younger. They underwent coronary angiography -- the X-ray procedure for examining heart arteries to see if they are clogged -- at Johns Hopkins Hospital over three years ending in April 1988.
The researchers focused on "premature" coronary heart disease, Kwiterovich said.
Apo B and Apo A-1 were "more strongly associated with premature coronary disease" than LDL or HDL cholesterol, blood's traditional fat-related indicators.
Apo (or apolipoprotein) B and Apo A-1 are considered lipid or fat-related predictors of coronary disease because they are sub-fractions of lipoproteins, the particles that transport cholesterol in the bloodstream.
Apo B is a major protein component of the outer shell of LDL (low-density lipoprotein) particles, known as "bad" cholesterol because it can accumulate in the walls of blood vessels, causing heart disease.
Apo A-1 is a major component of HDL (high-density lipoprotein), "good" cholesterol because it transports cholesterol to the liver, where it can be excreted from the body.
Cholesterol can be influenced by many factors including diet, alcohol intake, smoking and exercise. Thus, apolipoprotein levels provide a better estimate of the risk of coronary artery disease, Kwiterovich said.
Testing for Apo B and Apo A-1 now is available only at major medical centers and large hospitals, including Hopkins. The tests cost about $10 each, Kwiterovich said.
The scientists are conducting genetic and other types of studies in relatives of the 203 participants in the original study.
Genes found in families with a history of heart disease, plus lifestyle choices such as cigarette smoking, are key factors determining whether an individual develops heart disease during the prime of life, he said.
"So, you have to pay attention not only to your genes, but to your lifestyle," he said.