Breast Arterial Calcification Linked to CAD Risk in Women

Nancy A. Melville

September 07, 2018

The presence of breast arterial calcification, easily detected on standard mammography but typically considered inconsequential in breast cancer screening, shows significance as a possible marker of subclinical coronary artery disease (CAD) in asymptomatic women, new research suggests.

"Although breast arterial calcification, observed as an incidental finding on screening mammography, has been considered as a benign finding from an oncologic perspective, it needs to be considered as a women-specific risk marker for CAD risk," first author Yeonyee E. Yoon, MD, from the Department of Cardiology at Seoul National University Bundang Hospital and Department of Internal Medicine, Seoul National University College of Medicine, Korea, told Medscape Medical News.

The need for a women-specific risk marker for CAD is particularly pressing as mortality rates from the disease decline in men but remain unchanged in women, the authors noted.

Their findings were published online August 15 in JACC: Cardiovascular Imaging.

While standard screening algorithms, such as the Framingham risk score or atherosclerotic cardiovascular disease (ASCVD) risk, have limited accuracy in identifying women at high risk for CAD, some evidence has emerged suggesting that findings on common screening that women already receive — specifically breast arterial calcification and decreased bone mineral density, assessed by breast mammography and dual-energy x-ray absorptiometry (DXA), respectively — may indeed play a role in predicting risk.

To explore the association, Yoon and her colleagues evaluated data on 2100 asymptomatic women older than age 40 years who were enrolled in the Bone, Breast and CAD (BBC) study and simultaneously received DXA, digital mammography, and coronary computed tomography angiography screening at the Health Promotion Center, Seoul National University Bundang Hospital, between March 2011 and February 2013.

With a median age of 52 years (range, 40 to 80 years), 199 (9.5%) of the women had breast arterial calcification and 716 (34.1%) had low bone mass on DXA.

Meanwhile, 235 women (11.2%) had coronary artery calcification and 328 (15.6%) had coronary atherosclerotic plaque — both considered key risk factors for ASCVD.

After multivariate adjustment, the presence as well as severity of breast arterial calcification, calculated in a 10-year ASCVD risk assessment, were significantly associated with coronary artery calcification (area under the curve [AUC], 0.71 - 0.72; P = .016) and coronary atherosclerotic plaque (AUC, 0.66 - 0.68; P = .010) compared with those without breast arterial calcification.

Unadjusted assessments showed low bone mass and progression to osteopenia and osteoporosis were also associated with coronary artery calcification and coronary atherosclerotic plaque. However, that association lost significance after multivariate adjustment for factors including age.

Vascular vs Bone Mass Mechanisms

Yoon speculated that the association between the breast and coronary arteries may simply be stronger than the link between bones and vessels. However, she noted that the very low prevalence of low bone mass in the study was an important limitation, and she stopped short of ruling out bone mineral density as a possible additional risk factor for CAD.

"At present, given the accumulating evidence regarding the shared pathogenesis between the bones and vasculature in given individuals, it is premature to judge that bone mineral density does not provide added value for risk stratification," Yoon said.

Regarding the possible mechanisms linking breast arterial calcification to CAD, Yoon said some studies have pointed to the calcification playing a role in vascular stiffness.

"Exactly why breast arterial calcification signifies an increased cardiovascular risk is not well understood," Yoon said. "It may simply represent long-term exposure to known cardiovascular risk factors, or it may be indicative of medial calcification in other vascular beds."  

Medial calcification is known to increase vascular stiffness and likely explains the associations of breast arterial calcification with heart failure, in addition to coronary heart disease and stroke, she added.

With coronary artery calcification screening not typically covered by insurance in asymptomatic women, limiting its use in assessing the risk for subclinical CAD, the study suggests breast arterial calcification could represent an ideal window of opportunity for assessment, Yoon said.

"A significant relationship between breast arterial calcification and subclinical CAD would provide the opportunity to improve cardiac risk assessment in women, without additional cost and radiation exposure," she said.

Previous research also linking breast arterial calcification with a CAD risk includes a 2016 study  showing the calcification on digital mammography to be strongly associated with coronary artery calcification and superior to standard cardiovascular risk factors in the assessment.

That study, conducted at the Icahn School of Medicine at Mount Sinai, New York City, involved 292 women. Although rates of breast arterial calcification were significantly higher than in the current study (42.5% vs just 9.5%), the mean age of women in that study was also higher (61.5 vs 52 years).

The new findings importantly expand on the previous research, however, showing similar associations in an Asian population, said Tamar S. Polonsky, MD, from the Department of Medicine at the University of Chicago and Department of Preventive Medicine at Northwestern University, Chicago, Illinois.

"The findings by Yoon et al add to a growing literature that shows a significant association between breast arterial calcification and coronary atherosclerosis," she told Medscape Medical News.

"The results are important because many of the prior studies were done in the US and Europe, and so our understanding of the associations in other ethnic groups was more limited."

The findings of an association even among women who were younger — and with lower cardiovascular disease risk factors than in the 2016 study — are particularly compelling, Polonsky added.

"Even with those caveats, it's still notable that women with breast arterial calcification were almost three times as likely to have coronary artery calcification as women without breast arterial calcification," she said.

While the current study focused on subclinical atherosclerosis, previous research has also linked breast arterial calcification with heart failure, and Polonsky agreed that identification of the calcification findings on imaging should not be ignored.

"The presence of breast arterial calcification should prompt clinicians to perform a comprehensive risk assessment," she said.

"Depending on a woman's risk factors, that might mean moving ahead to coronary artery calcification testing to confirm the presence of atherosclerosis. For others, that might mean making sure that their blood pressure is well-controlled throughout the day," she suggested.

"And for most patients it could serve as a segue into discussions about a heart-healthy diet and exercise."

The study was supported by a grant from the Basic Science Research Program through the National Research Foundation of Korea, sponsored by the Ministry of Science, ICT & Future Planning, and a grant from the Seoul National University Bundang Hospital Research Fund. The authors and Polonsky had no disclosures to report.

JACC Cardiovasc Imag. Published online August 15, 2018. Abstract

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