Features March 2012 Issue

Elective Coronary Calcium Scans Are Not for Everyone

The scan can reveal calcium in your arteries, but this test remains a controversial tool.

Coronary calcium screenings, in simplest terms, are tests done to give doctors a picture of calcified plaque in your coronary arteries. Plaque build-up can be a risk factor for heart attack and stroke, so evidence of serious calcification could be a helpful predictor of future cardiac events and a red flag to begin or step up treatment.

The upper image from a coronary calcium scan shows no calcification in any of the coronary arteries. The small shape in the lower image indicates the presence of calcium buildup.

But the issue of calcium screenings is a complicated one. Steven Nissen, MD, chairman of the Robert and Suzzanne Tomsich Department of Cardiovascular Medicine at Cleveland Clinic, believes the screenings are overused and put patients at risk without evidence from large clinical studies that show screening for calcium save lives.

“The belief that it will help patients is the same as proof it will help patients,” Dr. Nissen says.

Cleveland Clinic cardiologist and cardiovascular imaging specialist Milind Desai, MD, agrees that too many physicians and medical centers order the screenings for patients who will not benefit from the tests. But he does see a value in screening subjects without documented coronary heart disease, but considered at “intermediate” risk of developing it.

An individual with no known coronary disease, but with risk factors such as a parent who died from an early heart attack or relatively high cholesterol, may fall into that “intermediate” classification. A formal profile of a patient is developed using many risk factors. An older adult who is obese, a smoker for many years and who has high blood pressure and a sedentary lifestyle would be a “high-risk” individual, and should be treated with medications and lifestyle changes regardless of what a calcium scan would show.

“If you’re at high risk, calcium scoring is not appropriate,” Dr. Desai says. “If you’re at high risk, what differently would you do? If it’s not going to change the way you treat a patient, it’s not recommended.” Likewise, someone considered low risk should not be screened.

However, based on recently published appropriateness criteria for computed tomography (CT), low-risk subjects with a strong family history of premature coronary artery disease (CAD) could also be deemed as appropriate candidates for calcium scoring.

How it Works
Calcium screenings are done using CT equipment to produce an X-ray-like image of the heart. A patient has small electrode patches placed on his chest and lies down on a table that moves in and out of a donut-shaped scanner. Images from multiple angles are taken to determine the presence of calcification, as well as the volume and mass of arterial calcium.

A calcium score is determined. Zero, of course, means you don’t have any calcification. A score of 100 or greater indicates the likelihood of heart disease; the higher your score the more likely you are to have heart disease or a heart attack.

“As we get older, everybody gets some calcification,” Dr. Desai says. “So your percentage of risk is also based on your age, race and gender.” Caucasians, for example, tend to have a higher percentage of calcification than Asians.

And if you’re in your 70s, a coronary calcium screening isn’t likely to change how you’re being treated, and is therefore not recommended.

The actual screening procedure is painless and usually takes just a few minutes. However, radiation is used in the screening, and that is why many physicians don’t support their use. Dr. Nissen says it’s not the amount of radiation in one screening that is the concern, but that a calcium CT scan is just adding to the cumulative effect of radiation exposure over a lifetime.

“We’re increasingly exposing patients to larger amounts of radiation with medical screenings,” Dr. Nissen says. “It’s cumulative, and this is one more straw that might break the camel’s back.”

Dr. Desai notes that calcium scoring, especially on the newer scanners, that use less radiation than other models. He also explains that the amount of radiation from a single scan is about the same as the amount of radiation you would get being on a plane for 100 hours.

The other downside to the screening is that it’s not a perfect tool. In many cases, it could trigger more layered tests and treatment for a problem that isn’t as serious as first thought.