There is a better way to determine risk of heart disease than measuring cholesterol, according to a new study by cardiologists from the Research Institute of the McGill University Health Centre (MUHC). This study shows that measuring the amount of a protein called apoprotein B or apoB, is a more accurate and efficient test than measuring cholesterol. These findings will be published in the March issue of the international journal, The Lancet.
"The tradition in clinical practice is to look at the levels and ratios of cholesterol as predictors of cardiovascular disease, " says Dr. Allan Sniderman, MUHC cardiologist and first author of the study. "Because this test has its limitations we decided to look at other possibilities. This study shows that apoB is a more robust indicator of a cardiac events and we suggest that it is superior to looking just at cholesterol levels."
Sniderman and colleagues from Australia, British Columbia, Sweden and The Netherlands, analyzed data from epidemiological studies and clinical trials involving thousands of heart patients. Their overwhelming conclusion was that, although measuring levels of cholesterol is a good start, it is not enough. "When we looked at data from patients who had their cholesterol levels lowered using medications, we found that their apoB levels were still high. This suggests that these patients are still at risk of having a heart attack. This is a concern because according to the cholesterol results, the patient was adequately treated," says Dr. Sniderman.
"Because apoproteins can be accurately and inexpensively measured in routine clinical laboratories, we suggest that this measurement should be brought into clinical practice. In addition, this test is considerably more convenient to the patients because fasting is not required, " concludes Dr. Sniderman.
Apoproteins are specialized transport proteins that carry lipids, or fats in the blood. Most of the cholesterol in blood is present in low-density lipoprotein (LDL) particles. Each LDL particle contains one molecule of apoB, which surrounds and stabilizes it. LDL particles differ in size depending on how much cholesterol they contain. The smaller LDL particles have less cholesterol, but are associated the most with coronary artery disease and are more dangerous to have circulating in the blood than the larger LDL molecules that contain more cholesterol. An increased number of LDL particles in the blood will lead to a greater risk of heart attacks or strokes. Lowering LDL particle number is the most powerful method now available to lowering the risk of heart attacks.