A Better Blood Test for Heart Risk?

By Ed Edelson
HealthDay Reporter
Friday, July 18, 2008; 10:00 AM

Copyright © 2008 ScoutNews, LLC. All rights reserved.

THURSDAY, July 17 (HealthDay News) -- Measuring proteins that carry cholesterol in the blood may give a better estimate of heart attack risk than measuring cholesterol, a major study finds.

The study focused on the ratio of two of the proteins, called apolipoprotein B100 (ApoB) and apolipoprotein A1 (ApoA1). The international team of researchers studied data on more than 27,000 people and found that the ratio of apolipoprotein B100 (ApoB) to apolipoprotein A1 (ApoA1) accounted for 54 percent of the risk of heart attack.

In contrast, the standard ratio of "bad" LDL cholesterol to "good" HDL cholesterol accounted for only 37 percent of the risk, researchers reported in the July 19 issue of The Lancet.

But the two testing methods are finely connected, said study lead researcher Dr. Matthew McQueen, professor of pathology and molecular medicine at McMaster University in Hamilton, Ontario, Canada.

"When you start looking at cholesterol and apolipoproteins, they are very closely related," McQueen said. "The protein that carries LDL cholesterol is ApoB, and the protein that carries HDL cholesterol is ApoA1. Clearly, you're not going to find differences [in a study] unless you do large numbers."

The finding directly contradicted a report last year from the renowned Framingham Heart Study, which found that measuring ApoB/ApoA1 ratios added nothing to standard risk assessments from ordinary blood cholesterol tests. The Framingham study -- which included about 3,300 middle-aged men, 291 of whom developed heart disease over 15 years -- was numerically much smaller than the new report, however.

"It's a question of statistical power in a study," agreed Dr. Lars Lind, professor of medicine at the University of Uppsala in Sweden, who wrote an accompanying editorial on the new findings in The Lancet. "This study is based on more than 10,000 cases. When it come to statistics, it is the number of cases that really counts," he said.

The fact that the study was done "not only in a large number of people but also in 52 countries and a variety of ethnic groups" also adds strength to the findings, McQueen said.