MESA Data Can Lend Context to Incidental CAC Findings

When incidental coronary artery calcium (CAC) is identified on noncardiac CT scans, contextualizing that information can help ease patient fears and aid clinical decision-making, according to the authors of a new study, who turned to the landmark Multi-Ethnic Study of Atherosclerosis (MESA) trial to put these CAC surprises in perspective.

As the volume of CT scans have increased for noncardiac indications like lung cancer, more patients without known atherosclerotic cardiovascular disease (ASCVD) are being told about incidental CAC and sometimes encouraged to see a cardiologist. And while these findings can affect prognoses, CAC normally exists in plenty of otherwise healthy individuals merely based on age, sex, or ethnicity, investigators point out.

Published this week in JAMA Internal Medicine, their research letter describes the prevalence of detectable CAC on chest CT among 6,814 MESA participants (mean age 62 years; 53% women) stratified by age, sex, and ethnicity. The authors say the information, summarized in a table, can swiftly aid clinicians and patients as a “helpful framework” for discussing what, if anything, to do about CAC findings.

“It’s important to frame it in a way that . . . could lower anxiety for some patients,” lead author Matthew C. Tattersall, DO (University of Wisconsin School of Medicine and Public Health, Madison), told TCTMD. “Our hope was that [this] could be a really useful clinical tool for physicians when faced with the task of patients coming in with incidental or nonincidental coronary calcium findings.”

Broadly, detectable CAC was found more often in men than women, regardless of age. Also, the age at which CAC prevalence exceeded 50% varied demographically, but it ranged from 50 to 54 years in non-Hispanic white men to older than 70 years in non-white and Hispanic women.

“Although CAC presence is associated with increased ASCVD risk regardless of age, CAC is common as age increases,” they write. “Its detection provides an opportunity to discuss ASCVD risk but should avoid provoking unnecessary patient anxiety.” For example, the paper points out that while about 90% of white men aged 70 to 74 years have CT-detectable CAC, only 50% of Black women of the same age do.

The authors also stress that because CAC seems to increase with age, “a finding of CAC on a CT scan should not reflexively result in a specialist referral or a prescription for a statin and/or aspirin, but rather a comprehensive ASCVD risk assessment with consideration of competing risks and patient preferences.”

They conclude: “The fundamental principle that test results can modify but cannot replace pretest disease likelihood is vital to the influence of incidental CAC detection on ASCVD risk assessment.”

Curbing Unnecessary Testing

Tattersall predicts that the number of incidental CAC findings will continue to grow, particularly as artificial intelligence (AI) tools for identifying and quantifying risk continue to grow.

“My biggest fear I think about from a clinical perspective [is while] there’s a lot of great things that that AI can accomplish, I do worry about a future where AI-provoked incidental findings could provoke reflexive testing and/or prescribing,” he said. “We should really never underestimate the therapeutic benefits of taking the time to provide a patient-centric, comprehensive cardiovascular risk assessment and patient education and really explain what coronary artery calcium really represents.”

In an accompanying editorial, Parveen K. Garg, MD, and David L. Brown, MD (both University of Southern California Keck School of Medicine, Los Angeles), agree that incidental findings may inspire clinicians to pursue more testing. “Although an individual’s adherence to lifestyle modifications and medical treatment may transiently improve after being shown a scan with calcifications, the findings also often lead to unnecessary testing, and even revascularization, which are of no benefit in asymptomatic persons,” they write.

Both the ongoing ROBINSCA and CorCal randomized trials are evaluating whether basing treatment strategies on CAC screening results in better outcomes than calculated risk estimates, Garg and Brown point out.

“Until the results of these trials become available, we caution against routine clinical CAC screening and agree with Tattersall et al that the appropriate response to the incidental discovery of coronary calcium should be to discuss vascular risk generally without provoking unnecessary anxiety, automatic referrals to specialists, inappropriate testing in absence of symptoms, or initiation of statin or aspirin therapy,” they advise.