Mammogram-Derived Clues to Cardiovascular Disease Often Unreported and Ignored

In what may represent a paradigm shift in women’s health, researchers say digital mammograms could provide two types of preventive health screening in one.  

Investigators led by Laurie Margolies, MD (Icahn School of Medicine at Mount Sinai, New York, NY), found that about 4 in 10 women have breast arterial calcification (BAC) on their mammograms that strongly correlates with an increased risk of CAD—even more so than traditional risk factors for cardiovascular disease.

Despite the fact that radiologists are trained to look during mammography for BAC, which often is a hallmark of early breast cancer, those findings are usually not included in mammography reports. With no additional cost, radiation, or time, inclusion of BAC in reports could signal a crucial next step in early identification of atherosclerotic disease, the researchers say.

Superior to Traditional Detection Methods

For their study, published online March 23, 2016, in JACC: Cardiovascular Imaging and scheduled for presentation on April 3 at the American College of Cardiology (ACC) 2016 Scientific Sessions, Margolies and colleagues reviewed data from 292 asymptomatic women ages 39 to 92 years with no known CAD who had undergone digital mammography and CT within 1 year of each other.

In a web briefing ahead of the ACC meeting, Margolies noted that the reasons for CT were individual to each patient. The majority (39%) were scanned for follow-up of a pulmonary nodule, while other indications included lung cancer screening, trauma, and infection, among others. Coronary artery calcium (CAC) scores were derived from the CT scans and compared with a novel BAC score that the researchers developed to quantify the number of vessels, the length of involvement of the vessel, and the density of calcification within the vessel. They also compared the BAC score with the Framingham Risk Score (FRS) and the 2013 Cholesterol Guidelines Pooled Cohort Equations (PCE).

BAC was detected in 42.5% of patients and was more common among older women, smokers, and those with hypertension or chronic kidney disease. On a scale of 0 to 12, mean BAC score was 2.2, with the likelihood of a score > 0 rising with increasing age such that nearly half of women ages 60-69 and nearly three-quarters of those over age 70 had a score above 0. Similarly, elevated CAC was found in 47.6% of all patients.

When BAC and CAC were compared, both tests showed good agreement, with BAC increasing along with increasing CAC. Both scores showed low levels of agreement with FRS and PCE, however, which the researchers say “parallels the generally poor correlation of calcified plaque with risk factor-based algorithms.” The addition of BAC score to FRS and PCE improved the discriminatory abilities of both tests somewhat.

Revolutionary and Practice Changing

“This is potentially practice changing in how radiologists read and report mammography,” Margolies said, adding that the situation parallels the outcry that led to Breast Density Notification laws, now mandated in 24 states, which require that women be informed after a mammogram if dense breast tissue is detected.

“I could envision that this is the very same type of practice-changing, revolutionary way of reporting and assessing risk,” she added, noting that “it’s very easy to report quantitative breast arterial calcification scores on all mammograms. And I would advocate that we do that, so we have the opportunity to improve and identify high-risk women by this simple analysis of a very common screening tool that’s already done.”

Margolies said she would hope that in addition to conveying BAC information to a patient’s referring physician, it would also be disseminated directly to the patient via a simple paragraph in lay language alerting them that they may be at risk for cardiovascular disease and may want to contact their doctor for further evaluation. As for what that would entail, she and her colleagues say it would most likely include a gated CAC scan, with subsequent adjustment or initiation of medical therapy.

In an editorial accompanying the study, Khurram Nasir, MD, and John McEvoy, MB BCh BAO (Baptist Health South Florida, Miami, FL), agree that adding BAC information to the mammography report is the right thing to do.

“There is little doubt based on the principles of clinical equipoise that BAC detection should be actively pursued in all mammograms performed, and its reporting and subsequent management tracked as part of the core quality performance measures,” they write.

But Nasir and McEvoy say rather than sending women after a mammogram on for further testing of CAC—which the current study suggests is likely to be elevated anyway—systems of care must be formulated so that physicians can act on the BAC information when it is found. Furthermore, they say, lack of clinical trial data in this area “should not be allowed to justify current inertia,” and that remaining “a silent bystander waiting for another study and preserving status quo should not be an option.”

The editorialists also hypothesize that screening the breasts for cancer and the chest for CAC at the same time with a dedicated breast CT instead of mammography “could represent an exciting dual-screening approach,” and could even be extended in some women to include lung-cancer screening as well.

Sources:

• Margolies L, Salvatore M, Hecht HS, et al. Digital mammography and screening for coronary artery disease. J Am Coll Cardiol Img. 2016;9:350-360. 
• Nasir K, McEvoy JW. Recognizing breast arterial calcification as atherosclerotic CVD risk equivalent: from evidence to action. J Am Coll Cardiol Img. 2016;9:361-363. 

Disclosures:

• The study was supported in part by the Flight Attendants Medical Research Institute. 
• Margolies and McEvoy report no relevant conflicts of interest. 
• Nasir reports serving on the advisory board for Quest Diagnostic and as a consultant for Regeneron. 

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