If the CAC score is zero, statin therapy should be withheld or delayed unless the patient is a cigarette smoker, has diabetes, or has a strong family history of premature ASCVD. A CAC score of 1 to 99 suggests statin therapy, particularly for patients 55 years and older. If the CAC score is 100 or greater or in the 75th percentile or greater, statin therapy is indicated for any patient unless otherwise deferred by the outcome of the physician–patient risk discussion.
This recommendation to selectively incorporate CAC scoring into ASCVD risk management has been controversial; the U.S. Preventive Services Task Force (USPSTF) found insufficient evidence that adding the CAC score to traditional risk assessment improves patient-oriented outcomes. In a previous American Family Physician editorial, Drs. John Mandrola and Andrew Foy argued that “it is unclear if knowing the coronary artery calcium score would improve decision quality or adherence to statin therapy.” However, a recent Diagnostic Tests article by Dr. Hu Ying Joanna Choi concluded that “CAC score is a strong predictor of coronary heart disease, CVD, and mortality risk and provides risk discrimination and stratification beyond that provided by traditional risk factor models.”
Incidental detection of CAC on chest computed tomography (CT) scans performed for other reasons in persons without clinical ASCVD was demonstrated in a previous study to increase statin prescriptions, cardiology clinic visits, and stress tests. Until recently, however, the prevalence of CAC in asymptomatic adults was not known. Using data from the National Institutes of Health-sponsored Multi-Ethnic Study of Atherosclerosis in persons aged 45 to 84 years without ASCVD symptoms at baseline, Dr. Matthew Tattersall and colleagues calculated CAC prevalence by age, sex, race, and ethnicity. They found that across all groups, most men in their early 60s had detectable CAC, and the majority of women had CAC by their early 70s. Nearly all (96 to 98%) non-Hispanic White adults in their early 80s had CAC.
The study authors concluded the following:
[A]lthough CAC presence is associated with increased ASCVD risk regardless of age, CAC is common as age increases. Its detection provides an opportunity to discuss ASCVD risk but should avoid provoking unnecessary patient anxiety.
Further,
given the high prevalence of CAC at older ages, 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.
Clinical summaries of current USPSTF recommendation statements on statins and low-dose aspirin for primary prevention of ASCVD in adults are available on the AFP website.
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This post first appeared on the AFP Community Blog.
