Cholesterol isn’t the only enemy
For years, cholesterol testing has been the gold-standard for assessing your risk of coronary artery disease. Now, other blood tests are being promoted as good risk predictors, and many people are wondering if they need those too.
There’s no single answer. If you are younger than 40 and healthy, you probably don’t need the tests. If you’re older and have been diagnosed with heart disease, you should already be taking measures to avoid a heart attack; the latest tests are unlikely to change your treatment. The new tests may be worthwhile if you are middle-aged with normal cholesterol levels but have other reasons for concern, such as a family history of early heart attack, or if you’re diabetic or having cardiac symptoms, such as chest pain.
Tests are constantly being developed as doctors identify new substances, that can be used to diagnose and treat coronary artery disease, the nation’s No. 1 killer. You may have heard reports about measuring homocysteine, C-reactive protein and very low-density lipoproteins, or VLDL. Earlier this month, the Food and Drug Administration approved the PLAC test to look for an enzyme considered another independent risk factor.
But some cardiologists caution that doctors have little experience with it, and a single test can’t paint the full picture of risk.
The PLAC test provides a “tiny bit of incremental information” to be considered along with a physical exam, health history and full risk assessment, said Dr. C. Noel Bairey Merz, medical director of the preventive cardiac center at Cedars-Sinai Medical Center in Los Angeles.
If you’re older than 40, or younger with significant cardiac risk factors, your doctor should order a blood lipid panel. This group of tests measures cholesterol, the waxy substance that’s part of artery-clogging plaque as well as triglycerides, another fat associated with atherosclerosis. It measures your total cholesterol, your high-density lipoprotein (HDL), or “good” cholesterol, and your low-density lipoprotein (LDL), or “bad” cholesterol.
Doctors sometimes order detailed tests of lipoproteins, particles that carry cholesterol around the blood. These may include measures of VLDL and lipoprotein(a), both associated with greater likelihood of narrowed arteries and heart attack. Most important are your levels of LDL cholesterol, which contribute to artery-clogging, and HDL cholesterol, which scrubs bad cholesterol from arteries. But even with high LDL, the key indicator of heart disease risk, studies have shown that one-third to one-half of heart attacks occur in people with normal LDL.
Blood tests provide one assessment of cardiac risk, but it’s also determined by family history and factors controllable by lifestyle changes and drugs. Factors include smoking, obesity -- particularly excess abdominal fat -- high blood pressure, diabetes and lack of exercise.
Some newer blood tests may help calculate your risk, but it’s not clear what to do with the information. For example, doctors can sometimes lower homocysteine by prescribing folic acid, vitamin B-6 and vitamin B-12. But there’s no proof that lowering your readings reduces the risk of heart attacks, strokes or death, said Dr. Debra R. Judelson, medical director of the Women’s Heart Institute in Beverly Hills.
Dr. Neil J. Stone, a professor of clinical medicine at Northwestern University in Chicago and a member of a national panel that formulates cholesterol testing and treatment guidelines, added: “We really don’t know if treating elevated homocysteine makes a difference.”
With inflammation emerging as a major player in cardiovascular disease, many doctors measure it with the high-sensitivity C-reactive protein test. In January, an expert panel from the American Heart Assn. and federal Centers for Disease Control and Prevention recommended against widespread hs-CRP testing while supporting its use to guide treatment of moderate-risk patients. They noted that hs-CRP tests aren’t yet standardized and that because the test picks up any inflammation, readings can be elevated by a cold or other infection.
The PLAC test picks up inflammation inside blood vessels by measuring an enzyme called lipoprotein-associated phospholipase A2, or LpPLA2. According to study results presented at a national cardiology meeting earlier this year, patients with normal LDL but elevated enzyme levels had twice the heart attack risk of those with normal enzyme levels, said Dr. Christie M. Ballantyne, director of the Center for Cardiac Disease Prevention at Baylor College of Medicine in Houston. For some patients, having the extra tests can drive earlier, potentially life-saving treatment.
“What you’d like to think is that the specialty testing can help identify someone whom you normally wouldn’t treat,” said Bairey Merz, of Cedars-Sinai, another member of the cholesterol guidelines panel.
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Major blood tests that predict risk
Blood tests are commonly used to help determine one’s risk of cardiovascular disease.
A basic blood lipid panel measures several types of cholesterol, including high-density lipoprotein (HDL) or “good” cholesterol, and low-density lipoprotein (LDL) or “bad” cholesterol and triglycerides. The American College of Cardiology recommends an annual panel for anyone older than 40 -- and for younger people with a known cardiac risk.
Many doctors also test C-reactive protein in patients at moderate risk. There are no national guidelines for homocysteine and several other tests.
Below are the latest guidelines for interpreting test results.
Lipid panel (milligrams per deciliter)
Total cholesterol
Desirable: less than 200
Borderline line: 200 to 239
High: greater than 240
LDL cholesterol
Optimal: less than 100 Desirable: 100 to 129
Borderline high: 130 to 159
High: 160 to 189
Very high: 190 and above
HDL cholesterol
Low (indicates more risk): less than 40High (indicates less risk): greater than 60
Triglycerides
Normal: less than 150
Borderline high: 150-199
High: 200 to 499
Very high: greater than 500
C-reactive protein (milligrams per liter)
Low risk: Less than 1.0
Average risk: 1.0 to 3.0
High risk: Greater than 3.0
Source: National Cholesterol Education Program of the National Heart, Lung and Blood Institute; the American Heart Assn.-CDC panel on C-reactive protein testing
