LDL Particle Number, Not Size, a Significant Predictor of CVD Risk

Peggy Peck

November 11, 2004

Nov. 11, 2004 (New Orleans) — The number, not the size, of low-density lipoprotein (LDL) cholesterol particles predicts heart disease risk, according to an analysis of blood samples from more than 3,200 participants in the Framingham Heart Offspring Study.

"It's the total particle number rather than size or anything else that is important," lead investigator Ernst J. Schaefer, MD, a professor at the Freidman School of Nutrition Science and Policy, chief of the Lipid Metabolism Laboratory, and senior scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston, Massachusetts, told Medscape

Dr. Schaefer presented the results of the analysis here at the American Heart Association (AHA) 2004 Scientific Sessions.

The study analyzed frozen blood samples from 1,529 men and 1,708 women who were followed for an average of eight years to monitor the development of fatal or nonfatal myocardial infarction, stroke, claudication, and angina. During the follow-up period, 220 men and 116 women developed one or more of those conditions.

The LDL particle numbers and size were analyzed using nuclear magnetic resonance spectroscopy, Dr. Schaefer explained at a press conference.

Considering just LDL factors, univariate analysis indicated that LDL particle size and number were significantly ( P < .001) associated with cardiovascular event risk in both men and women, but on multivariate analysis, particle size becomes nonsignificant, Dr. Schaefer said, and only particle number was a significant predictor.

Other known risk factors such as age, smoking history, diabetes, blood pressure, and high-density lipoprotein cholesterol level were significant for both men and women in the univariate model. But in the multivariate analysis, the best risk predictor model for men was age, systolic blood pressure, diabetes, smoking, and LDL particle number. For women, multivariate analysis identified age, systolic blood pressure, smoking, and LDL particle size, but not diabetes.

Asked about the availability of tests to measure LDL particle number, Dr. Schaefer said the tests were readily available. He suggested that LDL particle testing be done in "high-risk patients to optimize cholesterol profile." He added that "standard testing leaves something to be desired."

Sidney Smith, MD, director of the Center for Cardiovascular Science and Medicine at the University of North Carolina in Chapel Hill, and a spokesperson for the AHA, told Medscape that Dr. Schaefer's study is a significant example of recent advances in cardiovascular disease prevention and treatment.

"Think about where we have come in the past five years [in the management of cardiovascular disease]," Dr. Smith said. "We're now treating the risk factors rather than the disease." Dr. Smith was not involved in the study.

AHA 2004 Scientific Sessions: Abstract 3583. Presented Nov. 8, 2004.

Reviewed by Gary D. Vogin, MD