The addition of coronary artery calcium (CAC) scoring to the PREVENT atherosclerotic cardiovascular disease (ASCVD) equations provided only modest improvement across all risk groups, according to a new study.

The data, published in JAMA, also revealed that CAC scores were best used to help distinguish ASCVD risk among adults classified as having borderline risk by the PREVENT-ASCVD equations.

The findings come after the 2026 American College of Cardiology (ACC)/American Heart Association (AHA)/Multisociety guideline on the management of dyslipidemia recommended selective use of CAC scoring in adults with borderline or intermediate 10-year ASCVD risk when the decision about lipid-lowering therapy remains uncertain.

In addition, despite the increasing availability and usage of CAC scores, practitioners may not be using the scores appropriately or in the people who would most benefit from the data obtained, said Nilay S. Shah, MD, MPH, study investigator and assistant professor at Northwestern University Feinberg School of Medicine in Chicago.

This led Shah and colleagues to conduct a study using data from the Multi-Ethnic Study of Atherosclerosis, a longitudinal observational cohort study featuring adults (age, 45-79 years) without baseline ASCVD at six US sites.

ASCVD risk categories included low (< 3%), borderline (3% to < 5%), intermediate (5% to < 10%), and high (≥ 10%).

CAC Scores Modestly Improved Risk Prediction

Overall, 6098 participants (mean age, 61.4 years; 52% female) had a mean estimated 10-year ASCVD risk of 6.4% with the PREVENT-ASCVD base equations. Nearly half (49%) had a CAC score > 0.

Ten-year follow-up data indicated that 6% of participants had an ASCVD event.

When evaluated in all adults, adding CAC scoring to the PREVENT-ASCVD base equations raised the Harrell C statistic from 0.73 (95% CI, 0.70-0.75) to 0.75 (95% CI 0.73-0.77), a change of 0.02 (95% CI, 0.01-0.03). The resulting categorical net reclassification improvement was 0.095 (95% CI, 0.053-0.137).

The researchers also found that the calibration slope for the PREVENT-ASCVD base equations was 1.09 (95% CI, 0.93-1.25) vs 0.92 (95% CI, 0.81-1.03) after adding CAC equations.

Among borderline-risk adults, incident ASCVD was 1.9% for participants with a CAC score of 0, 3.9% for those with a CAC score > 0 and < 100, 7.4% for those with a CAC score ≥ 100 and < 300, and 14.3% for those with a CAC score ≥ 300.

In other data from the borderline subgroup, CAC reclassification was 0.085 (95% CI, 0.052-0.117). Half of the participants in this cohort who experienced an ASCVD event were correctly reclassified to a higher-risk category, whereas 61% of those without an event were correctly reclassified to a lower-risk category.

“Our study shows that obtaining a CAC score in all adults…does not really improve the ability to predict risk beyond the existing PREVENT risk calculator,” Shah said. “Instead, the better approach is to use PREVENT to calculate risk first and consider the use of a CAC score for those who are at borderline (3 to < 5%) or potentially intermediate (5 to < 10%) risk because these are the people for whom the information from a CAC score can best help refine and reclassify their risk level to make treatment decisions.”

Stacey E. Rosen, MD, executive director of the Katz Institute for Women’s Health in New York, who was not involved in the research, added that the findings reiterate the importance of a guideline-directed and personalized approach to risk assessment as outlined in the 2026 dyslipidemia guideline.

“Coronary artery calcium scores have been previously shown to correlate with PREVENT scores and are useful for personalizing risk management in appropriate patients,” said Rosen, who is immediate past president of the AHA.

“There are many tools available to reduce the risk of heart attack. Appropriate screening across the risk factor spectrum — blood pressure, blood glucose, lipids, kidney, and waist circumference along with social and lifestyle factors — helps us optimize treatment,” she said.

Caveats to Consider

Melis Sahinoz, MD, a final-year cardiovascular disease fellow at Vanderbilt University Medical Center in Nashville, Tennessee, noted two practical caveats to the findings. First, CAC reflects current calcified plaque burden, whereas the PREVENT risk score integrates the fuller picture of lifetime and multisystem risk, Sahinoz said.

“I would therefore be cautious about withholding therapy on the basis of CAC equals 0 in a patient whose PREVENT-estimated risk is already [at least] 5%; the risk score might reflect overall risk better,” she said.

“Second, a CAC of 0 in a borderline-risk patient is not a lifetime pass; if therapy is deferred, aggressive lifestyle-based prevention measures should still be reinforced and repeat CAC testing should be considered over the next 3-5 years,” Sahinoz added.

The Risk-Benefit Discussion

Shah stressed that while the study helps elucidate those who might best benefit from a CAC score, the foundation of a clinical conversation with a patient about heart disease prevention is the risk-benefit discussion for any testing or treatment.

“Regardless of a patient’s risk profile, cardiologists should discuss the implications of that risk profile with their patients,” Shah said, “and try to weigh the risks and benefits of any testing or treatment together with the patient in order to decide the best course of action.”

Sahinoz added that cardiovascular risk prediction is not meant to be one-size-fits-all, and there is now a broader toolkit to personalize risk assessment.

“The 2026 ACC/AHA/Multisociety Dyslipidemia Guideline provides LDL-C [low-density lipoprotein cholesterol] targets for CAC score ranges; the PREVENT equations allow the optional incorporation of early kidney dysfunction (urine albumin to creatinine ratio) and social determinants of health; and the recent cardiovascular-kidney-metabolic syndrome framework situates all of this within an integrated model of risk.

“Ultimately,” Sahinoz continued, “CAC is best used as a targeted decision-support tool that complements clinical judgment, shared decision-making, and a comprehensive assessment of cardio-kidney-metabolic risk.”

Shah, Rosen, and Sahinoz reported having no relevant financial relationships.

Brian Ellis is a freelance writer and editor who lives in Southwest Virginia.