Steve Haffner, M.D.ApoB: better marker for heart disease risk than “bad” cholesterol
A component of cholesterol called apolipoprotein B (apoB) may be more strongly linked to several heart disease risk factors than the LDL cholesterol for which millions of Americans are screened each year.
The National Cholesterol Education Program and the American Heart Association recommend therapy to reduce heart disease risk based on blood levels of low-density lipoprotein (LDL) cholesterol. It is considered “bad” cholesterol because it contributes to the buildup of atherosclerotic plaque in artery walls.
“This study indicates that apoB may be a better predictor of cardiovascular disease risk. It is the first study to explore LDL and apoB levels in an ethnically diverse population,” said Steve Haffner, M.D., professor of medicine at the University of Texas Health Science Cente in San Antonio, and co-author of the study.
LDL carries most of the cholesterol in the blood, but LDL particles come in various sizes. Research has shown that small, dense LDL particles are more often associated with atherosclerosis than large, “fluffy” LDL particles.
“Current LDL tests do not gauge the size or number of LDL particles. However, measuring apoB can tell us the number of LDL particles -- and that can indicate whether a patient’s cholesterol profile has more of the small, dense and dangerous sort,” Haffner said.
Haffner’s study examined links between abnormal blood sugar metabolism and the development of heart and blood vessel disease. His test subjects included African Americans, Hispanics and non-Hispanic whites. Of the test subjects who had elevated LDL levels for which cholesterol-lowering treatment was advised, 85 percent also had elevated apoB levels.
Nearly 10 percent of the subjects had normal LDL levels and elevated apoB. These people were more likely than those with high LDL and normal apoB levels to have abdominal obesity, high blood insulin levels and elevated clotting factors, which are CVD risk factors. The results were consistent across ethnic groups.
LDL level remains an important marker for heart disease risk. While the AHA does not recommend apoB testing, apoB may be a good way to determine whether cholesetrol-lowering drugs are working. The test is standardized, accurate, inexpensive, and does not require fasting, as does the LDL-C test.
Canada began recommending the apoB test in its national guidelines about two years ago and is updating the country’s guidelines for lipids (blood fats) and diabetes to include the apoB test.
While this study was partially funded by the NIH, Dr. Haffner was supported earlier in his career by AHA Grants-in-Aid from the Texas Affiliate.