Coronary calcium screening better predicts heart disease risk, research finds
Posted November 12, 2018 3:25 p.m. EST
(CNN) — Last year, President Donald Trump's doctors screened him for heart disease using a test unfamiliar to many Americans. Now, research shows that that test, either alone or combined with other evaluation methods, is better at predicting whether a symptomatic patient required heart surgery than the standard evaluation.
The test, a scan for coronary artery calcium or CAC, provides patients with a simple score or a quantifiable measure of how hardened their arteries have become. By contrast, the standard evaluation that doctors use to measure heart disease risk includes blood pressure, cholesterol levels, body weight, blood glucose and lifestyle factors, such as smoking status.
"If you're concerned about your risk of heart disease, then you should ask your doctor about the coronary artery calcium score," said Dr. Jeffrey Anderson, lead author of the new study, presented Monday at the American Heart Association Scientific Session conference. He is also a clinical and research physician and past director of cardiovascular research at Intermountain Medical Center Heart Institute in Salt Lake City, Utah.
A measure of actual plaque
Last year, White House physician Dr. Ronny Jackson revealed that as part of his physical exam, Trump had undergone a coronary calcium CT scan, a test that has been around since at least 1990. The president's score was 133, which indicates that some plaque is present and would place him in the middle-risk category as defined by the new study. The lowest-risk category includes patients with scores of zero, and the highest-risk category includes patients with scores of 1,000 or higher.
Anderson said the study questioned which of three types of evaluations is the best predictor of either a major coronary event, including heart attack, or the need for surgery to place a stent or perform a bypass. He and his colleagues looked at 1,107 symptomatic patients at Intermountain Medical Center who had been referred for a positron emission tomography (PET) test.
"These are patients with low-risk symptoms. Some have coronary disease; most don't," Anderson explained.
The first evaluation is the current standard used by doctors. The second includes all the same factors as the standard evaluation method, along with a patient's CAC score. The third evaluation was a CAC score alone.
The researchers followed the patients in the study for 1½ years to nearly three years. They discovered that the CAC score alone and the evaluation plus the CAC score did a better job of predicting who eventually needed to have bypass surgery or a stent placed than the evaluation method without the score, Anderson said.
The CAC score gives actual "anatomic information," he said. "You're actually seeing plaque -- not all the plaque, not the soft plaque, but advanced plaque where calcium is present."
None of the three evaluation methods did a good job of predicting heart attack risk, the study found.
Heart association urges use
Dr. Mary Norine Walsh, medical director of the heart failure and cardiac transplantation program at St. Vincent hospital in Indianapolis, said the new study -- along with a recommendation to use CAC scoring in new cholesterol guidelines from the American Heart Association -- show that "CAC scoring has really come into its own now."
"I would anticipate, based on this study and the guidelines, that this will broaden the use of CAC scoring for patients at risk" for heart attack, said Walsh, who was not involved in the study. "And my hope is that with the guidelines coming out and this growing evidence, that patients will have Insurance coverage for the study as well."
"When CAC scoring was initially done, there was pretty significant radiation exposure," said Walsh, who is also the American College of Cardiology's immediate past president. The technology has improved today, so "it's about the same equivalent radiation as getting a mammogram."
The test is like any CT scan, in which a patient lies on a table in a scanner and pictures are taken, she said. "It doesn't cause pain. You don't have to have an IV in," she said. "What we're able to see from the heart is the degree of calcification of the heart artery."
The higher the CAC score, the more calcium a patient has in his or her arteries and the higher the risk, she said. A score of zero shows no calcification in the coronary artery.
Generally, people who have risk factors such as "abnormal cholesterol levels, diabetes, family history of heart disease, hypertension, smoking -- all those traditional risk factors -- those people have a higher chance of having an abnormal CAC score," Walsh said.
She noted that a high CAC score is "not a natural progression with aging," though if you took a random sample of 80-year-olds, there would be more likelihood that they would have some calcium. "But what predicts higher calcium levels is the other risk factors," she said.
In recent years, she said, she's seen billboards advertising a "Father's Day special" in which people could gift their dads a CAC screening test.
Though hospitals appear to have pulled back on them recently, these ad campaigns were aimed at reassuring people who feared a heart attack, she said.
The new study, combined with the new recommendation to use the test in asymptomatic patients in the middle-risk category, when "put together, show us that this is going to be a test we're going to use more in the future," Walsh said.