Analysis Supports CAC for Personalizing
Statin Use

Richard Mark Kirkner

July 21, 2021

In patients with intermediate risk of atherosclerotic cardiovascular disease along with risk-enhancing factors, coronary artery calcium scoring may help more precisely calculate their need for statin therapy.

Furthermore, when the need for statin treatment isn't so clear and patients need additional risk assessment, the scoring can provide further information to personalize clinical decision making, according to a cross-sectional study of 1,688 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) published in JAMA Cardiology.

And regardless of coronary artery calcium (CAC), a low ankle brachial index (ABI) score is a marker for statin therapy, the study found.

The study looked at CAC scoring in the context of ABI and other risk-enhancing factors identified in the 2018 American Heart Association/American College of Cardiology cholesterol management guidelines: a family history of premature atherosclerotic cardiovascular disease (ASCVD), lipid and inflammatory biomarkers, chronic kidney disease, chronic inflammatory conditions, premature menopause or preeclampsia, and South Asian ancestry.

Any number of these factors can indicate the need for statins in people with borderline or intermediate risk. The guidelines also call for selective use of CAC to aid the decision-making process for statin therapy when the risk for developing atherosclerosis isn't so clear.

"The novel risk-enhancing factors are not perfect," said lead author Jaideep Patel, MD, director of preventive cardiology at Johns Hopkins Heart Center at Greater Baltimore Medical Center. He noted that the 2018 dyslipidemia guidelines suggested the risk for cardiovascular events rises when new risk-enhancing factors emerge, and that it was difficult to predict the extent to which each enhancer could change the 10-year risk.

Utility of CAC

"In this setting, the most significant finding that supports the utility of CAC scoring is when CAC is absent — a CAC of 0 — even in the setting of any of these enhancers, whether it be single or multiple, the 10-year risk remains extremely low — at the very least below the accepted threshold to initiate statin therapy," Patel said.

That threshold is below the 7.5% 10-year ASCVD incidence rate. Over the 12-year mean study follow-up, the ASCVD incidence rate among patients with a CAC score of 0 for all risk-enhancing factors was 7.5 events per 1,000 person years, with one exception: ABI had an incidence rate of 10.4 events per 1,000 person years. "A low ABI score should trigger statin initiation irrespective of CAC score," Patel said.

The study found a CAC score of 0 in 45.7% of those with one or two risk-enhancing factors versus 40.3% in those with three or more. "Across all the risk enhancers (except low ABI), the prevalence of CAC of 0 was greater than 50% in women; that is, enhancers overestimate risk," Patel said. "The prevalence of CAC of 0 was approximately 40% across all risk enhancers; that is, enhancers overestimate risk."

Patel said previous studies have suggested the risk of a major cardiovascular event was almost identical for statin and nonstatin users with a CAC score of 0. "If there is uncertainty about statin use after the physician-patient risk discussion," he said, "CAC scoring may be helpful to guide the use of statin therapy."

Senior author Mahmoud Al Rifai, MD, MPH, added: "For example, if CAC was absent, a statin could be deprescribed if there's disutility on the part of the patient, with ongoing lifestyle and risk factor modification efforts." Al Rifai is a cardiology fellow at Baylor College of Medicine, Houston.

Patel said: "Alternatively, if CAC was present, then it would be prudent to continue statin therapy."

While South Asian ethnicity is a risk enhancing factor, the investigators acknowledged that MESA didn't recruit this population group.

Study Confirms Guidelines

The study "supports the contention of the [AHA/ACC] guidelines that, in people who are in this intermediate risk range, there may be factors that either favor statin treatment or suggest that statin treatment could be deferred," said Neil J. Stone, MD, of Northwestern University, Chicago, and author of the 2013 ASCVD risk calculator. "The guidelines pointed out that risk-enhancing factors may be associated with an increase in lifetime risk, not necessarily short term, and so could inform a more personalized risk discussion."

The study findings validate the utility of CAC for guiding statin therapy, Stone said. "For those who have felt that a calcium score is not useful," he said, "this is additional evidence to show that, in the context of making a decision in those at intermediate risk as proposed by the guidelines, a calcium score is indeed very useful."

Stone added: "An important clinical point not mentioned by the authors is that, when the patient has a CAC score of 0 and risk factors, this may be exactly the time to be aggressive with lifestyle to prevent them from developing a positive CAC score and atherosclerosis, because once atherosclerosis is present, treatment may not restore the risk back to the original lower state."

Patel, Al Rifai, and Stone have no relevant relationships to disclose. A number of study coauthors disclosed multiple financial relationships.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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