Coronary Calcium Scan: A Heart Test That Can Help Guide Treatment
Many doctors recommend the heart test to pinpoint which patients would benefit from treatment to reduce their cardiovascular risk.,
For nearly 45 years, doctors have relied on well-known cardiovascular risk factors to determine how patients should be treated to ward off a heart attack or stroke. These factors include high blood pressure, elevated cholesterol, diabetes, a history of smoking, obesity and a family history of premature heart disease.
When a patient has either no risk factors or many of them, treatment decisions are usually straightforward. Doctors typically tell patients with no risk factors to keep doing what they’re doing, while those at high or moderately high risk are often advised to start medications along with adopting lifestyle measures, like a heart-healthy diet and regular exercise.
But when patients are in the middle-ground of risk, or are known to be at elevated risk but resist advice to take medication or change their habits, there’s a test that can help to clarify the best course of treatment and help convince reluctant patients to follow it.
The test is a coronary calcium scan, which takes 10 to 15 minutes and usually costs about $100 to $400, though it is often not covered by insurance. The test uses specialized CT X-rays to assess the presence and amount of calcium (actually bony deposits of plaque that signal atherosclerosis, or “hardening of the arteries”) in the blood vessels that feed the heart.
The radiation dose is low, about the amount in a mammogram, and calcium scores can range from zero up into the thousands. The higher the level of calcium in coronary arteries, the greater the patient’s likelihood of suffering a cardiovascular event like a heart attack or stroke within the next decade.
Recently, a friend in his early 60s with a family history of heart disease and a somewhat elevated cholesterol level had a coronary artery calcium test suggested by his doctor. Although the test showed my friend’s arteries had very little calcium, it wasn’t zero, and the doctor decided to prescribe a statin to lower his serum cholesterol and prevent worsening of atherosclerosis, the artery-clogging disease that underlies most heart attacks.
In 2018, the United States Preventive Services Task Force acknowledged that the calcium test can indeed help doctors assess a patient’s cardiovascular risk. But the agency concluded that there was not yet adequate evidence to show that the test’s results improved patient outcomes above what is typically recommended, based on standard risk factors alone.
Still, many doctors who practice preventive cardiology believe otherwise. They say the results of a calcium scan can pinpoint which patients would benefit from treatment to reduce their cardiovascular risk and help motivate patients to follow through, for example, by changing their diet or taking medication.
Dr. Sadiya S. Khan, a preventive cardiologist at the Feinberg School of Medicine at Northwestern University, said that she and many other cardiologists follow the American College of Cardiology/American Heart Association’s conclusion that the calcium test can help guide therapeutic options, especially for patients with a borderline or intermediate risk of developing cardiovascular disease.
In an editorial on “The Potential and Pitfalls of Coronary Artery Calcium Scoring,” published in JAMA Cardiology in October, Dr. Khan and her co-author, Dr. Ann Marie Navar, a cardiologist at the University of Texas Southwestern Medical School, concluded that for middle-aged and older adults like my friend, the calcium test is one of the best and safest ways to identify the presence of otherwise hidden atherosclerosis.
Why younger adults should care.
Results of a calcium scan can also be important for younger men and women — and sometimes for their physicians, who may not take risk factors in younger patients as seriously as they should.
“Given the robust association between coronary artery calcium and cardiovascular disease,” Drs. Khan and Navar wrote, “the presence of coronary artery calcium in young adults should be a red flag for a high-risk patient.” As Dr. Khan explained in an interview, “The presence of any calcium in coronary arteries is a sign of having heart disease.”
When atherosclerosis first starts to develop, the arterial lesions, called plaque, are not calcified, explained Dr. Philip Greenland, also a preventive cardiologist at Northwestern. Rather, the lesions acquire the bony deposits over time that gradually increase when the plaque ruptures and is repaired. The healing process causes calcification, he said.
Dr. Greenland cautioned that patients and doctors should never assume that a calcium score of zero means there’s nothing to worry about. He said that in men under 40 and women under 50, “you can’t rely on coronary artery calcium alone, because the level is typically zero even in the presence of atherosclerosis.”
Rather, he and Dr. Kahn said, in younger adults, follow-up tests and medical advice should be based on the extent of patients’ cardiovascular risk, including whether they have any symptoms of heart disease, like shortness of breath when climbing stairs or chest pain when exerting themselves.
The good news, and bad news, about a zero calcium score.
Dr. Greenland said that people with “a low-risk factor profile and a calcium score of zero have a kind of warranty that they won’t have a heart attack within 10 years.”
“But,” he continued, “if risk factors put you above a 20-percent 10-year risk of a cardiovascular event, even zero calcium is not sufficient to provide such a warranty.” You can determine your risk profile, which considers such factors as age, gender and race, using the calculator at cvriskcalculator.com.
The value of this advice is underscored by the findings of a large study, also published in October in JAMA Cardiology. A cardiology team from Aarhus University Hospital in Denmark reported that among nearly 24,000 high-risk patients who had symptoms of cardiovascular disease, 14 percent of those with obstructions in their coronary arteries nonetheless had no evidence of coronary calcium.
For patients in the 10-year study who were younger than 60, a “sizable proportion” of obstructive coronary artery disease occurred among those with no coronary artery calcium, yet they faced a seriously increased risk of heart attack and death, the Danish team wrote.
Based on the Danish report, Dr. Khan said, “Having a calcium score of zero is not a get-out-of-jail-free card,” especially for younger men and women, who may still be at high risk for coronary artery disease despite the absence of coronary calcium. She noted that in the United States, Black adults tend to have less coronary artery calcium compared to their white peers but may still be at high risk because of other cardiac risk factors.
Dr. Khan emphasized that regardless of calcium score, all patients at high risk, and especially those with symptoms of heart disease, should be treated with medication and lifestyle changes. Among helpful measures are lowering elevated levels of blood pressure, cholesterol and glucose; adopting a heart-healthy diet; getting regular physical exercise; and striving to achieve and maintain a normal body weight.