Breast arterial calcification from mammogram may predict CV risk in women
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RANCHO PALOS VERDES, Calif. — Breast arterial calcification measured during mammography is a readily available surrogate marker of atherosclerotic CVD and may predict subclinical CAD and microvascular disease, according to a speaker.
A large proportion of CV events occur in women considered “low risk,” with a 10-year risk for atherosclerotic CVD calculated at less than 7.5%, Lori B. Daniels, MD, MAS, FACC, FAHA, professor of medicine and director of the cardiovascular intensive care unit at Sulpizio Cardiovascular Center at UC San Diego, said during a presentation at the Cardiometabolic Health Congress Women’s Cardiometabolic Health and Wellness Masterclass. Guidelines do not recommend statins or aggressive treatments for these women; better screening methods are needed to understand their risk for a CV event, Daniels said.
“What if a single biomarker could identify risk in women who did not know they were at risk, cost nothing, not even additional time, did not require a blood draw, and millions of women are already getting it measured every single year?” Daniels said. “Could that marker be mammography? It turns out that, besides looking for breast cancer, there are a lot of data in those mammograms. As we get into the digital age, we can establish risk on this.”
Correlation with CV risk factors
Breast arterial calcification differs from coronary artery calcification and is seen in about 13% of women overall, Daniels said. It is not as common in young women; about 10% of women in their 40s vs. 50% or more of women in their 80s will have breast arterial calcification on mammography. It increases with age and in the setting of diabetes, kidney disease, parity and some CV risk factors, Daniels said, noting there was an inverse association between breast arterial calcification and smoking.
“To some degree, hypertension, obesity and lipids do not track directly and have a little bit of an inverse association as well, so it is a very interesting marker and not 100% straightforward,” Daniels said. “One of the key things to remember is coronary artery calcification occurs in the intima vs. medial calcification. That may be why we see different associations, but it also why it can help us. It may be more associated with stiffening of the vessels and HF-type outcomes.”
There are few long-term studies available looking at breast arterial calcification and predicted CVD, Daniels said, though a few meta-analyses and reviews are available. In a meta-analysis published in 2015 in Atherosclerosis, researchers found breast arterial calcification prevalence was 12.7% among women in breast cancer screening programs. Although longitudinal studies (n = 3) were scarce, breast arterial calcification appeared to be associated with an increased risk for CVD events, with adjusted HRs for CHD ranging from 1.32 (95% CI 1.08-1.6) to 1.44 (95% CI, 1.02-2.05).
“But these were old studies before the digital age of mammography, when it was more of a crude yes or no, I have calcium in my breast arteries or I do not,” Daniels said. “Researchers were not able to quantify it like we can now.”
‘Catch those clues early’
Newer methods are now available to quantify breast arterial calcification that can identify the number of vessels involved and the extent of calcification, Daniels said. Instead of trained readers, computerized algorithms, currently under development, could help to provide a breast arterial calcification score.
“Now we can develop computer algorithms to measure it on digital mammography automatically and develop a breast arterial calcification score, like a CAC score, which can allow finer tuning of risk,” Daniels study.
In a single-center, retrospective study published in Circulation in 2018, Daniels and colleagues analyzed data from 293 women who underwent both digital mammography and CAC assessment by CT scan with 1 year of each other. A computer algorithm measured the breast arterial calcification score and compared it with CAC. Breast arterial calcification scores were significantly correlated with CAC Agatston scores (r = 0.38, P < .001). Overall, breast arterial calcification had a positive predictive value (PPV) of 77% for presence of CAC and a specificity of 88%. Among women younger than 60 years of age, the PPV was 75% with a specificity of 95%, Daniels said.
“What if you see breast arterial calcification in a woman under [age] 60 [years]?” Daniels said. “It has pretty good specificity ruling in the presence of CAC and works especially well in women without heart disease at baseline, which is exactly the group we want it in, to catch those clues early.”
Breast arterial calcification may represent an early marker of vascular stiffness and endothelial dysfunction and may be useful for identifying women at increased risk for HF, Daniels said.
“I propose we start using it,” Daniels said. “It is there, it is free, and it is a call to our radiology colleagues to at least start telling us if it is present. Now, we have a paradigm for where mammogram can not only assess breast cancer risk in women, but maybe also cardiovascular risk too. We need to be detectives and find the clues and then act on them.”
Reference:
- Bui QM, et al. Circulation. 2018: doi:10.1161/circ.138.suppl_1.15384.
- Hendriks EJE, et al. Atherosclerosis. 2015;doi:10.1016/j.atherosclerosis.2014.112.035.