The ratio of two forms of apolipoprotein in the blood is substantially better at predicting heart attack risk than the standard method of using cholesterol ratios. Measuring apolipoprotein ratios should thus be introduced into clinical practice worldwide. These are the conclusions of authors of an Article in this week's edition of The Lancet.
Apolipoproteins are fat (lipid) binding-proteins that form part of lipoproteins, sub-microscopic spherical particles that transport dietary lipids through the bloodstream from the intestine to the liver; cholesterol is a type of lipid found in the blood of all animals. High ratios of LDL (bad) cholesterol to HDL (good) cholesterol are strongly associated with cardiovascular disease because these promote plaque development in arteries (atherosclerosis). This disease process can lead to heart attack, stroke, and other vascular disease.
Professor Matthew McQueen, Population Health Research Institute and McMaster University, Hamilton, ON, Canada, and colleagues did a study of acute heart attack in 12461 cases and 14637 age-matched and sex-matched controls in 52 countries. Non-fasting blood samples were available in 9345 cases and 12120 controls. Concentrations of blood fats, lipoproteins and apolipoproteins were measured, and cholesterol and apolipoprotein ratios were calculated, as was the risk associated with acute heart attack.
The researchers found that the apolipoprotein B100 (ApoB) / apolipoprotein A1 (Apo A1) ratio accounted for 54% of the risk of heart attack. By contrast, the ratio of bad to good cholesterol accounted for 37% of the risk, whereas the ratio of total cholesterol to good cholesterol accounted for 32% . The ApoB to Apo A1 ratio was thus almost twice as powerful a predictor of this risk.
The authors conclude: "The non-fasting ApoB/ApoA1 ratio was superior to any of the cholesterol ratios for estimation of the risk of acute heart attack in all ethnic groups, in both sexes, and at all ages, and it should be introduced into worldwide clinical practice."
In an accompanying Comment, Dr Lars Lind, University Hospital, Uppsala, Sweden, says that apolipoproteins can be measured in a standardised and automatic manner at a similar cost to conventional cholesterol analysis, and concludes that substituting cholesterol tests with those analysing apolipoprotein ratios would be a demanding but not impossible task.
Professor Matthew McQueen, Population Health Research Institute and McMaster University, Hamilton, ON, Canada T) +1 905 527 4322 Ext. 46100 E) mcquemat@hhsc.CA
Dr Lars Lind, University Hospital, Uppsala, Sweden T) +46 730502878 E) lars.lind@medsci.uu.se
http://multimedia.thelancet.com/pdf/press/INTERHEART.pdf
Journal
The Lancet