A new study presented Sunday at the American College of Cardiology annual Scientific Sessions provides evidence that testing for levels of the protein Apolipoprotein B-100 (ApoB) could be a more accurate indicator of a patient’s heart disease risk than the standard tests that measure levels of HDL (the good) and LDL (the bad) cholesterol.
ApoB is produced in the liver and helps transport fat and cholesterol throughout the human body. It is known to carry a number of different lipoproteins which are considered “bad” cholesterol including: chylomicrons, very-low-density lipoproteins (VLDL), low density lipoproteins (LDL), and intermediate density lipoproteins (IDL). ApoB attaches to cell receptors and allows cholesterol into your cells, and once it is broken down release the fat and cholesterol into the bloodstream.
“Testing for ApoB doesn’t tell you how much cholesterol a patient has, but instead it measures the number of particles that carry it,” said Jeffrey L. Anderson, Intermountain Health cardiologist and principal investigator of the study. While it’s still not a commonly ordered test, we found that it’s both being used more often, and it could lead to a more accurate way to test for lipoprotein-related risk than how we do it now. For example, some people have normal LDL cholesterol levels but still have a large number of particles due to an abundance of small, dense LDL particles.”
To make their determination on the utility of measuring ApoB levels, the team at Intermountain Health conducted a retrospective study of patients’ electronic health records from 2010 until the beginning of 2022. During this time period, the researchers noted an increase in doctors in the system ordering the ApoB tests, from 29 cases in 2010 to 131 in 2021.
The investigators also found that that ApoB level were positively correlated with LDL cholesterol, but that the ApoB/LDL cholesterol ratio increased as LDL cholesterol decreased, suggesting the presence of an excessive number of atherogenic small, dense LDL particles—those particles with smaller amounts of LDL cholesterol per particle.
The results suggested that developing a better assessment of particle number via ApoB may be better at evaluating cardiovascular health risk. Anderson noted this measurement could be particularly beneficial for patients who have LDL cholesterol levels that are considered normal, including those with metabolic syndrome (such as diabetes), or who have low HDL and high triglyceride levels.
“Data suggest that these particle numbers increase risk to a greater extent than just cholesterol levels alone,” Anderson noted. “ApoB could help us identify a population of patients with normal or even low LDL numbers but who are at higher risk and should be more aggressively treated.”
While evidence is pointing toward ApoB being a more accurate method for assessing cardiovascular disease risk, it’s not likely to supplant the standard HDL and LDL testing in the near future. The test itself is a bit more expensive and has not yet made significant inroads within the healthcare system. Regardless, Anderson added that it can be considered a new tool for clinicians to use to refine their testing among the aforementioned patient groups.
