Statin Therapy and ApoB Goals:  The New Frontier By Paula Rasich Reviewed by Elizabeth Klodas, MD, FACC (CardioSmart) August 11, 2008--If you’re taking statins (cholesterol-lowering medications), the best way to protect your cardiovascular health may be to cut cholesterol levels even lower than current recommendations, a new study finds.

Research indicates that apolipoproteinB (apoB), a protein that carries cholesterol and other fats in the bloodstream, is a better predictor of cardiovascular events than “bad” LDL cholesterol. ApoB is present on all the cholesterol particles (including LDL, and above and beyond LDL) that could contribute to plaque formation, so the apoB level provides a more “complete” evaluation of cholesterol risk.  The apoB goal for patients with a history of heart disease is less than 90 mg/dL. Some have suggested that an even more aggressive goal of less than 80 mg/dL should be considered.

While a blood test to measure the apoB level is available, it is not routinely performed with a cholesterol test and represents an additional expense.  However, apoB levels can be estimated from the routine cholesterol profile.  It turns out that in healthy people not taking statins an apoB of 90 has been shown to correlate to an LDL level of about 100 and a non-HDL (another version of bad cholesterol) level of about 130. (Non-HDL cholesterol can be calculated from the standard cholesterol profile by subtracting HDL cholesterol from the total cholesterol measurement).

To investigate the relationship between non-HDL, LDL and apoB levels---before and after statin treatment---a team of researchers led by Christie M. Ballantyne, MD, director of the Center for Cardiovascular Disease Prevention at Baylor College of Medicine and Methodist DeBakey Heart and Vascular Center in Houston, examined data from the MERCURY II (Measuring Effective Reductions in Cholesterol Using Rosuvastatin Therapy) Trial. In this multi-center, international study 1,993 patients at high risk for coronary heart disease followed a standard diet and were randomized to receive one of five statin treatments for 16 weeks.

A statistical analysis revealed that an apoB of 90 in high risk patients treated with statin therapy was equivalent to a non-HDL of 100 and an LDL of 70, a change from 130 and 100, respectively, for patients not receiving statin therapy.

“We showed that when you are treating high risk patients with statins, the relationship between apoB and LDL is different from healthy people,” says Dr. Ballantyne.  “The findings are very clear cut, if you knock the LDL and non-HDL down to the targets of less than 70 and less than 100, you will probably get the particle concentration [apoB] in a good zone.”

The findings add to the growing body of data suggesting that very low LDL targets are appropriate in high risk individuals receiving statin therapy.  This study was published in the August issue of the Journal of the American College of Cardiology. 

Sources:

Ballantyne CM et al. Statin Therapy Alters the Relationship Between ApolipoproteinB and Low Density Lipoprotein Cholesterol and Non-High Density Lipoprotein Cholesterol Targets in High-Risk Patients: The MERCURY II (Measuring Effective Reductions in Cholesterol Using Rosuvastatin Therapy) Trial. Journal of the American College of Cardiology, August 2008.

Christie Mitchell Ballantyne, MD, MPH, Director of the Center for Cardiovascular Disease Prevention at Baylor College of Medicine and the Methodist DeBakey Heart & Vascular Center, Houston, Texas.