Blood test warns of hidden heart disease risk

The first test measures a protein called apolipoprotein B (or apoB for short), which contributes to the formation of plaque that blocks arteries. The other test is lipoprotein(a), which measures a type of bad cholesterol.

High levels of each are said to increase the risk of heart disease.

A growing number of specialists and primary care physicians say these tests can help provide more accurate and earlier warning of possible heart disease than common tests like LDL, the best-known indicator of bad cholesterol. In some cases, these lesser-known tests can identify at-risk people whose lipid profiles appear normal on standard lipid tests.

Proponents say the test should complement, not replace, standard lipid testing generally recommended for adults every one to six years.

Other doctors are wary of ordering the test, citing the lack of consensus on what normal levels are, whether they should be treated, and how to treat them, as well as the added cost. Medical guidelines in the United States do not uniformly recommend testing.

How these tests help

A growing body of research on apo B suggests that it may be a better predictor of heart disease risk than the better-known LDL cholesterol.

Up to 20 percent of people with normal LDL cholesterol levels have high Apo B levels, according to Dr. Mark Penn, a cardiologist and medical director at clinical testing company Quest Diagnostics.

“Measuring apoB allows us to provide a much more accurate assessment of the number of cholesterol-carrying particles in the blood that can lead to atherosclerosis,” said Dr. Shriram Naramshetty, a preventive cardiologist at the Palo Alto VA Medical Center.

Likewise, high lp(a) levels, which start at 30-50 mg/dL and are thought to affect roughly 20-30% of people, are associated with an increased risk of heart attack, stroke, and other cardiovascular diseases.

ApoB levels can be lowered by taking certain medications, such as statins, or by making dietary changes, such as limiting saturated fats.

LP(A), on the other hand, is genetic and doesn’t change much throughout life, but if you test high, you can lower your risk of heart disease in other ways, including with medication and by making changes to your diet and exercise.

Buddy Touchinski, a chiropractor who runs an integrative-medicine clinic in Pennsylvania, decided last year to give all his patients both tests after his own Lp(a) test showed levels well above the high-risk threshold.

“If people had started more aggressive treatment 20 years ago, they might not have had plaque buildup in their arteries at all,” Tatchinski said.

Touchinski was able to lower his Apo B levels by reducing his intake of foods like red meat, butter and full-fat dairy products, increasing his exercise and taking low doses of a statin and another cholesterol-lowering drug called ezetimibe.

Who should get it?

Doctors are divided on who should get these tests.

“Some people are doing everything they can to be healthy, but still have anxiety,” says Dr. Nalin Dayawansa, a research and interventional cardiology fellow at The Alfred Hospital in Melbourne, Australia. “A lot of that information is just noise and a waste of money if it doesn’t directly influence what you do.”

The American College of Cardiology and the American Heart Association do not recommend lp(a) testing for everyone, instead recommending it for adults with a family history of premature heart disease or for people with atherosclerotic cardiovascular disease that cannot be explained by common risk factors such as smoking.

The groups say there may be benefits to measuring apo B, especially for people with high levels of triglycerides, or fats, in the blood.

People with signs of insulin resistance and abdominal obesity would also likely benefit from Apo B testing, says Dr. Daniel E. Soffer, a physician and lipidologist at the University of Pennsylvania and past president of the National Lipid Association, who estimates that, combined with those with high triglyceride levels, these groups make up about 40% to 50% of the U.S. adult population.

Several major European medical organizations now recommend that all adults have their LP(a) levels measured at least once, and in the United States, the National Lipid Society, which represents experts in dyslipidemia, adopted the same recommendation in March of this year.

Children can also benefit from lp(a) testing, especially if one or both parents suffered a heart attack or other cardiovascular disease at an early age, said Dr. Christy Ballantyne, president of the National Lipid Association and professor of medicine at Baylor College of Medicine.

“Atherosclerosis is easier to reverse when you’re young,” says Ballantyne.

Gaining momentum

Testing companies such as LabCorp and Quest have begun offering consumer-directed and at-home tests for patients who want to avoid the hassle of ordering tests from their doctor.

Lp(a) and ApoB tests are generally not covered by insurance, with out-of-pocket costs ranging from approximately $25 to $150.

Jennifer Mannino says she wishes LP(A) had been part of the standard preventive care before her 48-year-old husband went into cardiac arrest in 2020. Complications left him struggling with short-term memory and executive function.

After his cardiac arrest, he had an LP(a) test that was high; standard lipid tests he had taken the previous year had levels that would be classified as near optimal. He added a new medication to the statin he was already taking, and his LDL cholesterol levels dropped significantly.

“Having one more piece of information can help you have a better conversation with your doctor,” Mannino says.

Write to Alex Janin at alex.janin@wsj.com.