But a growing number of doctors and researchers say it’s time to move away from the outdated emphasis on “good” or “bad” cholesterol.
Instead, apolipoprotein B (abbreviated “apoB”) may be a more accurate marker of heart attack risk.
better cholesterol test
Research shows that heart risk is determined by the number and type of cholesterol particles in the blood, not by cholesterol itself. ApoB is the particle that actually carries cholesterol into the circulation.
Decades of evidence show that measuring the number of apoB particles in the blood can predict cardiovascular risk much more accurately than standard good cholesterol/bad cholesterol lipid panels, but cholesterol guidelines Its existence is hardly acknowledged. Current guidelines only offer it as an option for certain high-risk patients.
As a result, most patients and even many doctors don’t even know that a better cholesterol test exists. “Old habits die hard,” says Anne-Marie Navar, a preventive cardiologist at UT Southwestern Medical Center in Dallas.
Standard Cholesterol Panel calculates total cholesterol amount or the concentration (in milligrams per deciliter) of “bad” cholesterol or LDL in the blood (technically LDL-C). Cholesterol is a fatty substance and therefore not soluble in water, so it must be transported in small particles known as lipoproteins.
Testing for apoB, a protein on the outside of the particles that carry LDL. number These lipoprotein particles in the blood. In addition to LDL, it also captures other types of cholesterol, such as IDL (intermediate density lipoprotein) and VLDL (very low density lipoprotein), which carry triglycerides.
Why is this important? As we learn more about heart disease, scientists have realized that apoB particles are more likely to get stuck in artery walls, thickening them and eventually forming atherosclerotic plaques. I am. Therefore, the total number of apoB particles is more important than the total amount of cholesterol they carry.
In most people, apoB and LDL-C track fairly closely, said Alan Snyderman, a cardiology professor at McGill University in Montreal. However, some people have “normal” amounts of LDL-C but high concentrations of apoB particles. This is a condition called “mismatch” and means you are at higher risk. However, traditional cholesterol panels cannot catch these patients.
“Two people can have exactly the same amount of cholesterol and still have very different numbers of particles bouncing off their artery walls,” says Snyderman, who has studied apoB for decades.
Why do people with low cholesterol still have heart attacks?
This discrepancy may help explain why even people with optimal cholesterol levels have heart attacks. His widely cited 2009 study found that more than half of patients hospitalized after a heart attack or other cardiovascular event had “normal” LDL cholesterol levels when using standard measurement techniques. got it.
Testing for apoB rather than LDL-C may help identify those at higher risk due to this discrepancy. “We’re losing people we could have saved,” Snyderman said.
There is no lack of evidence to support comparing apoB testing with traditional LDL-C testing. Three large clinical trials (called) have been conducted in the past few years. improve it, fourierand Odyssey) found strong support for apoB as a better risk predictor than LDL-C.
“There was already a significant amount of data on apoB,” says Seth Martin, professor of medicine and director of the Progressive Dyslipidemia Program at Johns Hopkins University. “But the guideline recommendations for apoB don’t provide much guidance.” Martin is part of a group of cholesterol experts working with the American Lipid Association to help doctors perform and understand apoB testing. is.
Currently, U.S. cholesterol guidelines do not suggest that doctors test apoB on all patients, but only on patients at certain risk, such as those with high triglycerides. Suggests testing. As a result, some insurance companies will refuse to pay for the test (I was charged $25 by United Healthcare earlier this year). However, some international lipid guidelines support apoB testing.
Salim Virani, co-author of the latest US cholesterol guidelines published in 2018, acknowledged that apoB is “a better predictor of cardiovascular events when compared to LDL cholesterol.” But he says another number on the standard lipid panel, non-HDL cholesterol (total cholesterol minus HDL cholesterol), effectively conveys the same information.
“Clinicians can measure ApoB if they wish, but non-HDL cholesterol provides free information from a standard lipid panel that clinicians can use for risk stratification beyond LDL cholesterol.” Baylor University said Virani, a former professor and current associate professor at the School of Medicine. Director of Research at Aga Khan University in Karachi, Pakistan.
Proponents of apoB argue that it is more specific than non-HDL cholesterol and can help doctors identify individuals whose cholesterol levels are “normal” but may slip through the cracks. ing. “It’s not that non-HDL or LDL-C are bad lipid markers; it’s that apoB is a better lipid marker,” says John Wilkins, a professor at Northwestern University Feinberg School of Medicine. “It’s easy to add to a standard lipid panel.”
ApoB testing may be especially important for people under 40, Wilkins added. He is a co-author of his 2016 study showing that young people with high apoB levels but normal LDL are at increased risk of coronary artery calcification, a relatively advanced stage of heart disease. “There is a very clear correlation between apoB levels and subsequent disease,” he says.
Patients found to have high apoB levels are encouraged to use the same treatments and lifestyle changes used for other indicators of high cholesterol, such as daily exercise, a diet with more plant-based foods and less saturated fat, and lower cholesterol. The patient is likely to be advised to adopt statin therapy (e.g. use of statins). or other lipid-lowering medications.
“The challenge is that atherosclerosis develops silently over years or even decades,” says Johns Hopkins’ Martin. “If someone develops plaques, due to high lipids or other factors, it can be a completely silent process until the plaques break down and cause a heart attack. So identifying the disease, especially in its early stages. “If you have a family history of , it’s important to be aware of this from an early age,” he says. “It’s about being ahead of the curve.”
