Instant Insights: Apolipoprotein B

Instant Insight: ApoB (PODCAST TRANSCRIPT)

[00:00:00] Welcome to Healthier World with Quest Diagnostics. Our goal is to prompt action from Insight as we keep you up to date on current clinical and diagnostic topics in cardiovascular, metabolic, endocrine, and wellness medicine.

[00:00:18] Hello everyone. Thank you for joining. The goal of today's episode is to give you instant insight into the utilization of Apolipoprotein B for cardiovascular risk assessment. I'm Dr. Maeson Latsko, clinical specialists with Quest’s cardio-metabolic center of excellence at Cleveland heartlab.

[00:00:35] So let's start with the basics. We know that cardiovascular disease is the number one killer of men and women and claims more lives than all cancers combined. Yet the risk for CVD is still largely under identified. In fact, the first sign and symptom of disease is death in 64% of women and 50% of men. LDLC is a commonly used indicator to identify risk and determine treatment initiation.

[00:00:59] Yet 50% of patients hospitalized with coronary artery disease have normal LDLC levels. Normal LDLC. So what tools can we add to our repertoire to better predict who is at risk? The answer begins with a solid understanding of the biological makeup of lipoproteins.

[00:01:18] A lipid panel measures the concentration of lipids, such as cholesterol and triglycerides present in an individual. However, triglycerides and cholesterol are hydrophobic, meaning that they cannot mix with blood. And to flow throughout the body, cholesterol and triglycerides are contained within a phospholipid shell. These lipid carrying vehicles are called lipoproteins. Wrapped around each of these cholesterol delivering and potentially atherogenic particles is an apolipoprotein B molecule or ApoB. ApoB is the primary apolipoprotein on all non HDL particles.

[00:01:53] Apolipoprotein service structural components for lipoprotein particles and act as ligands to bind LDL receptors. Keep in mind that each atherogenic particle or non HDL particle carries exactly one ApoB molecule on it. Thus ApoB levels correspond to the total number of atherogenic particles in circulation. Individuals with similar amounts of LDL cholesterol can have different levels of cardiovascular risk because it is the lipoprotein particles that can get trapped in the artery wall and lead to atherosclerotic buildup. The more particles present, the higher, the likelihood of infiltration and retention in the blood vessel wall, promoting atherogenic progression. ApoB correlates to the number of particles in circulation.

[00:02:36] Therefore having high levels of ApoB can lead to an increased risk for cardiovascular events and death. This is particularly relevant in individuals who have high numbers of particles or higher levels of ApoB compared to what is expected based on their LDLC values alone.

[00:02:53] the concept of having higher ApoB and higher particles compared to what is expected Based on their standard lipid panel is called discordance.

[00:03:00] And this concept can be thought about using an analogy. If cholesterol represents the people needing to be transported to an event and ApoB represents the number of cars that are needed to get them there. We hope that people will carpool, this will cause less traffic, less damage to the road and less fuel emissions. You can think about cholesterol and ApoB in the same way. We want our cholesterol to be packaged efficiently into particles that can transport them through the body. So that there can be less particles in circulation and less risks for atherogenic progression.

[00:03:32] Let's go through an example to really solidify this concept. Say we have a patient with an LDLC value of a hundred milligrams per deciliter. That means that their LDLC falls within the 20th percentile.  If their ApoB is 78 milligrams per deciliter, which also falls into the 20th percentile. They do not show discordance both values fall within the 20th percentile.

[00:03:55] However, if a patient has an LDL C value of 100 mg per deciliter, but an ApoB value of 103 mg per deciliter, their LDL C falls within the 20th percentile, while their ApoB falls within the 60th percentile. They do show discordance.

[00:04:13] This means that cholesterol is not packaged efficiently. And there significantly more particles needed to transport LDL cholesterol. These particles are small, dense, and more atherogenic. Given that risk tracks with particle count and quality, this person is at greater risk for cardiovascular disease and events.

[00:04:33] So who is at greater risk of having increased particle count? Various conditions can lead to an increased particle number. And this is often driven by metabolic dysfunction, which is rooted in insulin resistance. And these conditions include things like obesity, metabolic syndrome, Diabetes and hypertriglyceridemia. Discordance can also be seen in patients who are secondary prevention or on liquid lowering therapies, which can decrease LDLC more significantly than April B.

[00:05:03] ApoB outperforms LDL C and non HDL C as a predictor of cardiovascular disease events. This is particularly relevant in individuals who show discordance, indicating that LDL C may underestimate the risk in these individuals.

[00:05:18] Recent data confirms that ApoB can identify individuals with a 50 percent greater risk for myocardial infarction beyond what is expected based on LDL C values alone.

[00:05:28] Additionally, ApoB levels are associated with residual cardiovascular risk and all cause mortality in patients on statin therapy.

[00:05:37] For these reasons, ApoB has been recognized by many professional societies, including the American Heart Association, the American College of Cardiology, the American Association of Clinical Endocrinology, the National Lipid Association, and the European Society of Cardiology, and others.

[00:05:54] Each societal recommendation highlights ApoB as the preferred measure of cardiovascular risk when testing is available, particularly in individuals with a borderline to high 10 year ASCVD risk or heightened risk for metabolic dysfunction, and those syndromes that leave a patient at greater risk for discordance, such as insulin resistance, high triglycerides, obesity, and type 2 diabetes.

[00:06:19] Today, we took a deep dive into the strength of ApoB in accurately predicting lipid driven cardiovascular risk. Cardiovascular disease is multifaceted, and can be caused by an interplay between metabolic dysfunction, which can drive lipid driven risk and lead to increased particles that are small, dense and more atherogenic, contributing to vascular inflammation.

[00:06:42] With the utility of cutting edge technology to provide a comprehensive assessment, Quest diagnostics aims to create a healthier world, one life at a time.

[00:06:51] That's a wrap on this episode of Healthier World with Quest Diagnostics. Please follow us on your favorite podcast app, and be sure to check out Quest Diagnostics Clinical Education Center for more resources, including educational webinars and research publications. Thank you for joining us today as we work to create a healthier world, one life at a time.