The New Heart Tests: Which Ones Should You Have?

The New Heart Tests: Which Ones Should You Have?
Experts explain the pros and cons of coronary calcium scores, carotid artery ultrasound, and CT heart scans.
By Charlene Laino
Reviewed by Louise Chang, MD

We've all heard the stories: someone seemingly healthy, with normal cholesterol levels and no obvious risk factors, drops dead of a heart attack. How can this happen?

Morteza Naghavi, MD, says it's because traditional risk factors may not tell you what you really need to know: whether your arteries are diseased.

"Why are cholesterol, smoking, family history so lousy? Because they're just risk factors," says Naghavi, chairman of the Society for Heart Attack Prevention and Eradication (SHAPE) and director of American Heart Technologies in Houston.

"They don't speak to whether the arteries are diseased. So we need to directly visualize the artery. Is there plaque and is the artery dilating properly? You can have a diseased artery regardless of how may risk factors you have."

That disconnect has led more doctors to recommend that patients undergo high-tech heart tests that offer detailed images of the blood vessels as a means of lowering heart disease risks. The three tests -- calcium coronary scores, carotid artery ultrasound, and CT heart scans (CT angiography) -- "are all good at determining early atherosclerosis, or hardening of the arteries," says American Heart Association (AHA) past president Robert Bonow, MD, head of cardiology at Northwestern University's Feinberg School of Medicine in Chicago. "They can help to identify people early on that need aggressive risk factor modification."

But as with anything, these tests have their merits and drawbacks. So how can you tell if these tests are for you? To find out, WebMD spoke with three leading heart health experts: Naghavi, Bonow, and Todd C. Villines, MD, co-director of cardiac CT at Walter Reed Army Medical Center in Washington, D.C.
1. Coronary Calcium Scores

What Are Coronary Calcium Scores?

Calcium is one component of plaque that can build up inside the coronary arteries that supply oxygen-rich blood to heart muscle. Measuring it can help determine the level of plaque buildup that leads to narrowing of the heart arteries, the hallmark of coronary artery disease.

During the test, you lie in a hollow CT scanner. X-ray beams create multiple images of the heart; a computer measures the amount and density of calcium deposits in the artery walls and provides a calcium score. The score can range from 0 to more than 400, and any score over 100 is associated with an increased risk of heart disease.

"Studies have consistently shown that the higher your calcium score, the higher your risk of heart attack or other coronary artery disease event," Villines says. One of the most recent studies, published last year in the New England Journal of Medicine, showed that the coronary calcium score predicted heart events -- heart attack, death from coronary heart disease, or chest pain (angina) -- among men and women of all races. In that study, people with a coronary calcium score of 101-300 were more than seven times as likely to experience a heart event than someone with no evidence of coronary calcium; people with higher scores were at even greater risk.
Who Should Get Coronary Calcium Scores?

People at intermediate risk of heart disease based on traditional risk factors. This includes men over 50 with at least one added risk factor and women over 60 with at least two added risk factors, such as high blood pressure or high cholesterol, according to Villines. In these individuals, the need to commence medications to control these risk factors may not be clear.

For people at intermediate risk, a high calcium score would likely lead to more aggressive lifestyle changes, such as aspirin therapy, and even high-dose statin drugs to control cholesterol, Bonow says.

On the other hand, if you're at high risk to begin with (because you have diabetes or because you have heart or vascular disease), you should already be on aggressive therapy, so measuring the calcium score wouldn't change anything, Bonow explains. And people at low risk are unlikely to have calcium buildup; even if they do, their overall risk of a cardiac event is usually still low, he says.

One exception may be low-risk women, Villines says. "Data from the Multi-Ethnic Study of Atherosclerosis trial showed that women at low risk and a high calcium score faced the same risk of heart attack or dying of heart disease as people at high risk. So even though it's not integrated into the guidelines, I would consider this test in women aged 45 to 65 with at least one risk factor -- or even with no risk factors when there is a strong family history. It might change management."

Naghavi believes that all men ages 45 to 75 and women ages 55 to 75 should undergo screening with either the coronary calcium scan or carotid artery ultrasound -- regardless of whether they have other risk factors. People may have low cholesterol levels or other low risk factors and still have heart problems, he says. "We need to go beyond traditional risk factors."

Bonow, Villines, and many other doctors disagree, saying that further study is needed to show that widespread screening will truly help. "Testing everyone would lead to a lot of costs and detection of minor abnormalities that mean nothing but can cause needless anxiety and further testing," Bonow says.

Advantages of Coronary Calcium Scores

Villines notes that the only study directly comparing coronary calcium scores to carotid artery ultrasound showed that calcium scores are better at predicting risk of future heart problems. Adds Bonow, "Of the two tests, coronary calcium is probably the better studied. Calcium in the blood vessels is clearly a marker of atherosclerosis, and it can be quantified."

"The test is painless and quick," he adds.

Disadvantages of Coronary Calcium Scores

Because calcium deposition is not the first thing that happens during plaque buildup, "a negative test doesn't mean you don't have [any] atherosclerosis," so a low or absent calcium score may make you feel safe even if you're at risk, Bonow says.
Furthermore, as we age, the chance that some plaque has deposited is significant and it is common for older individuals to display calcification in their arteries. So a positive test doesn't necessarily place you at risk: In one study, low amounts of calcium were detected in two-thirds of the participants who did not experience coronary events. The key may be your relative score -- how you compare to your peers. You may be at increased risk only if your score is significantly higher than expected based upon your age and gender.

Also, the test does involve some exposure to radiation, although "at very low doses," Bonow says. A new AHA advisory says CT scans should be used judiciously to minimize exposure to ionizing radiation, but that medically appropriate examinations should not be avoided.

How Much Do Coronary Calcium Scores Cost?

The test typically costs $200 to $500. As with most screening tests, Medicare and other insurers usually do not pick up the tab.
2. Carotid Artery Ultrasound

What Is Carotid Artery Ultrasound?

This test uses ultrasound and sophisticated software to quantify the thickening of the inner walls of the carotid arteries that supply blood to the brain, a sign of early atherosclerosis. "Studies in over 50,000 patients have shown that if you're in the 75th percentile or higher for your age group, you have a higher risk of coronary heart disease and stroke," Villines says. Being in the 75th percentile means that 75% of your peers had less artery thickening than you.

Who Should Get Carotid Artery Ultrasound?

As with coronary calcium scores, carotid artery ultrasound should be reserved for people at intermediate risk of heart disease based on traditional risk factors, according to Bonow and Villines. Naghavi says SHAPE "recommends carotid artery ultrasound or coronary calcium scores as a first line of screening for men over 45 and women over 55. However, of the two tests, I'd lean toward calcium scores."

Advantages of Carotid Artery Ultrasound

This is a painless noninvasive test that can be performed easily in the doctor's office and does not expose the patient to radiation.

Disadvantages of Carotid Artery Ultrasound

Unlike coronary calcium scores, carotid artery ultrasound "does not inform you directly about the heart," as you are looking at the arteries in the neck, Naghavi says.

Also, the accuracy of the test is very dependent on the skill and expertise of the technologist performing the study, "so you need a trained operator who knows all the current protocols. Be sure to ask if your institution follows the most current guidelines," Villines advises.

How Much Does Carotid Artery Ultrasound Cost?

The test typically costs $200 to $500. As with most screening tests, Medicare and other insurers usually do not pick up the tab.
3. CT Heart Scans

What Is a CT Heart Scan?

During CT heart scans (also know as CT angiography), patients receive a contrast dye through an IV. X-rays are passed through the body and are picked up by detectors in the scanner. Special software uses the information gathered during the scan to create 3D images of the coronary arteries on a computer screen.

CT angiography scans give doctors a detailed look at the coronary arteries, which supply blood to heart muscle, without cardiac catheterization.

Who Should Get CT Heart Scans?

While contrary calcium scores and carotid artery scans are used to evaluate people without symptoms, CT angiography is typically reserved for intermediate-risk people with symptoms such as chest pain or shortness of breath that could be due to coronary heart disease, Villines says.

CT heart scans can also be useful if a patient is at low risk for heart disease and has "mildly abnormal" results on an exercise stress test. "Right now, these patients are referred for catheterization, but the CT scan could help avoid that," he says.

Advantages of CT Heart Scans

The technique is quick, producing pictures within five to 10 seconds, compared with 30 to 45 minutes for cardiac catheterization, the "gold standard" for evaluating blood vessel obstructions. It's noninvasive, with less risk and discomfort than catheterization, which often requires sedatives and sometimes a night in the hospital.

Disadvantages of CT Heart Scans

It fails to produce good images in people with a lot of calcium deposits in their arteries, Bonow says. It should not be used in people with chronic kidney disease or severely obese patients, Villines says.

There are also concerns about cancer risks. According to a new study, CT angiography has the potential to expose patients to high doses of radiation, and methods available to reduce radiation dose are not frequently used. A recent study reported that the average radiation exposure from a CT angiogram evaluation is equivalent to 600 chest X-rays.

Villines says that over the past two years, Walter Reed doctors have been able to reduce radiation during CT angiography by 50% to 70% through the use of radiation-sparing techniques. Patients should ask if such methods will be used before having the procedure, he advises.

How much do CT Heart Scans cost?

The CT scan, including the doctors' fee, costs about $1,000. Medicare and other insurers are still evaluating whether to pay for the scans.

In summary, there are several tests which can be used to determine whether or not you have diseased arteries. The results of such tests could influence the type of preventive treatments which are recommended. However, no test is perfect and regardless of test results, optimizing lifestyle choices still remains a cornerstone of heart disease prevention.

When it comes to your heart health, there are no hard and fast rules, our experts say. Talk to your doctor if you have any concerns.