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Why a Protein Test Could Predict Heart Disease Risk Better Than Cholesterol

A picture of a stethoscope, medication and an ECG trace.
Credit: Towfiqu barbhuiya on Unsplash.
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A new study by Intermountain Health researchers suggests that testing for levels of apolipoprotein B-100 (ApoB) might predict heart disease risk more accurately than testing cholesterol levels alone. The research was presented at the 2023 American College of Cardiology Annual Scientific Sessions in New Orleans.

Diagnosing heart disease

Heart disease remains the leading cause of death in the United States, where one person dies every 34 seconds from the condition. While treatment options are available, their success can depend on the cause and type of heart damage a patient experiences, making early diagnosis of paramount importance to clinicians.

Current standard of care diagnostic approaches include cholesterol testing, where the levels of high-density lipoprotein (HDL) and low-density lipoprotein (LDL) are measured. The latter, often referred to as “bad” cholesterol, makes up most of the body’s cholesterol. Excessive levels of LDL can cause a build-up in the walls of blood vessels, forming a plaque that can narrow the vessels and restrict blood flow to and from the heart.

LDL is transported throughout the body via a protein called ApoB, which can also carry other fat molecules. Researchers from Intermountain Health, led by Dr. Jeffrey L. Anderson, suggest that ApoB testing could help to identify patients at higher risk of a cardiovascular event, even if they have “normal” LDL levels. “Testing for ApoB doesn’t tell you how much cholesterol a patient has, but instead it measures the number of particles that carry it,” Anderson explains.

ApoB could more accurately predict heart disease risk

The researchers analyzed electronic patient health records from 2010–2022, discovering that ApoB testing, while still fairly uncommon, is being increasingly used; in 2010, 29 cases were reported, rising to 131 in 2021.

Examining the patients’ records, Anderson and colleagues discovered that ApoB levels positively correlated with levels of LDL, but the ratio of ApoB:LDL increased as overall LDL levels decreased. This suggests that there may be an excessive number of small, dense particles that carry reduced amounts of LDL per particle. The authors say that this finding promotes the use of ApoB testing for heart disease risk: “Data suggest that these particle numbers increase risk to a greater extent than just cholesterol levels alone,” Anderson notes. “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 it’s [ApoB testing] 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,” Anderson added. “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.” 

ApoB testing is more expensive than standard cholesterol tests, and it’s wide-range adoption in the diagnostics space is yet to be seen. Anderson and colleagues do not foresee ApoB testing overriding the use of LDL and HDL testing any time soon. However, they do argue that it should be increasingly adopted as a valuable tool for physicians to refine heart disease risk, particularly in patients with metabolic conditions, such as diabetes or prediabetes or low HDL and high triglyceride levels.

This article is a rework of a press release issued by the 2023 American College of Cardiology Annual Scientific Sessions. Material has been edited for length and content.