The decade-long, single-healthcare-system study gives insights into how physicians are using CAC tests and in which patients.
MONTREAL, Canada—Whether a patient undergoes coronary artery calcium (CAC) screening depends on the type of doctor they see, with large sex differences observed over the past decade at a single healthcare system, according to retrospective data.
From 2013 to 2023, researchers led by Ato Howard, MD (University of Pittsburgh Medical Center, PA), found that higher-risk female patients were more often referred for a CAC scan when they saw a cardiologist compared with a generalist—defined as a physician who practices community medicine, family medicine, geriatrics, or internal medicine. Additionally, they showed that generalists ordered scans for lower-risk patients regardless of sex compared with cardiologists, but male patients had a lower risk than females who were scanned.
The differences observed between physician types are not unexpected, Howard told TCTMD, as cardiologists would be more likely to keep up with clinical guidelines, which changed in 2019. In the US, measuring CAC is recommended (class IIa) as a noninvasive screening tool for patients at intermediate risk when there is uncertainty about starting statin therapy.
“You would expect cardiologists to at least be more familiar with the cardiology guidelines and also be more familiar with the fact that patients can have traditional and nontraditional risk factors,” he said. “You would expect them to be ordering the studies on the patients who are not necessarily at the highest risk because already they’re high risk and so they already should be treated and not necessarily need further risk stratification.”
A CAC scan is helpful for identifying patients at risk for atherosclerotic cardiovascular disease (ASCVD) who might be “missed” by those traditional risk factors, Howard continued. The findings “made us feel good about ourselves, that we saw that cardiologists were ordering them more for women. In our population of patients, the women tended to have higher risk factor markers for atherosclerotic disease.”
The retrospective study, which was presented recently at the 2025 Society of Cardiovascular Computed Tomography (SCCT) meeting, included 9,868 patients (mean age 60 years; 50.6% female) who underwent CAC scanning at a large healthcare system between 2013 and 2023.
About one-third of patients were referred by cardiologists and the remaining two-thirds by generalists. Female patients were older than males on average (62 vs 58 years) and were at greater risk for ASCVD as measured by a risk-enhancing score that was based on age and several other risk factors and comorbidities (2.22 vs 2.03; P < 0.001 for both).
In our population of patients, the women tended to have higher risk factor markers for atherosclerotic disease. Ato Howard
Importantly, use of CAC scans increased steadily throughout the study for both sexes and type of referring physicians, with a slowed annual growth observed between 2017 and 2021 and an inflection point thereafter likely caused by a surge of patients being seen following the change in guidelines, increased reimbursement, and the end of the COVID-19 lockdown protocols, Howard said.
Cardiologists overall referred higher-risk patients for CAC scanning compared with generalists (2.31 vs 2.02; P < 0.001). Women remained higher risk than men regardless of whether they were referred by a cardiologist (2.35 vs 2.25; P = 0.04) or generalist (2.13 vs 1.93; P < 0.001).
The reasons why physicians in the study made the referrals remain unclear, according to Howard. “I think it showed us that cardiologists are actually maybe using the coronary artery calcium study in a way that maybe they’re looking for patients who generally would be missed more often than not,” he said. It’s possible some female-specific risk factors like pregnancy and timing of menopause, which were unaccounted for, might have led to differences in referrals, he added.
“At least for now, we’re able to identify that there is some signal that there’s a difference in the ordering patterns between providers, and especially if they’re either a cardiologist or not a cardiologist,” Howard continued.
He said he’d like to see similar data from other centers to see how they compare. Ultimately, “it goes to show at least how we should be approaching our patients—always trying to think about how a test can be helpful for people and also trying to think about what the test is going provide from an information standpoint to help us make a decision,” he concluded. “Theoretically, we could be making a difference by testing the patients who are actually going to benefit from it if we’re able to find something that they can be treated for.”