CAC may best risk score for decisions on aspirin for primary prevention
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Using coronary artery calcium scores may better define who should receive aspirin for primary prevention than using the Pooled Cohort Equations, researchers reported in Circulation.
“Implementation of current 2019 American College of Cardiology/American Heart Association guideline recommendations together with the use of CAC for further risk assessment may result in a more personalized, safer allocation of aspirin in primary prevention,” Miguel Cainzos-Achirica, MD, MPH, PhD, research associate at the Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, and colleagues wrote.
The researchers analyzed 6,470 participants from the MESA cohort study, dividing them into strata based on 10-year atherosclerotic CVD risk from the Pooled Cohort Equations: less than 5%, 5% to less than 20%, and 20% or more.
Participants also were divided into four groups based on CAC scoring: 0, 1 to 99, 100 to 399, and 400 or more.
The researchers calculated number needed to treat at 5 years based on a 12% RR reduction in CVD events, and a number needed to harm at 5 years based on a 42% RR increase in major bleeding events.
Based on the Pooled Cohort Equations, only 5% of the cohort would qualify for consideration of aspirin for primary prevention based on having an estimated 10-year ASCVD risk of 20% or more, Cainzos-Achirica and colleagues wrote.
Among the 3,540 participants younger than 70 years who had not taken aspirin and were not at high bleeding risk, the number needed to treat to prevent one CVD event was 476 and the number needed to harm from one major bleeding event was 355, according to the researchers.
However, when the researchers analyzed the cohort based on CAC score, they found subgroups for whom the number needed to treat was lower than the number needed to harm.
For example, in those with a CAC score of 100 or more, the number needed to treat was 140 and the number needed to harm was 518, the researchers wrote, noting that in those with a CAC score of 400 or more, the number needed to treat was even lower at 100, but the number needed to harm could not be determined because of few bleeding events in the subgroup.
In participants with a CAC score of 0, the number needed to treat was substantially larger than the number needed to harm (1,190 vs. 567), Cainzos-Achirica and colleagues wrote.
“Detection of CAC 100 and particularly of CAC 400 might be used to identify asymptomatic individuals (younger than 70 years and with no high bleeding risk features) in whom the benefit/harm balance of aspirin is likely to be favorable,” the researchers wrote. “However, the 5-year number needed to treat with aspirin would be relatively high in populations at low overall baseline ASCVD risk such as that included in the present study. On the other hand, detection of CAC = 0 may be used to avoid aspirin therapy for primary prevention among individuals with high estimated ASCVD risk.” – by Erik Swain
Disclosure: One author reports he served on an advisory board for Bayer.
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