Two new analyses evaluated whether adding coronary artery calcium (CAC) imaging to the PREVENT risk calculator improves 10-year prediction of heart attacks, strokes, and deaths. Both studies used data from the Multi-Ethnic Study of Atherosclerosis (MESA) and examined whether CAC changes risk estimates enough to influence decisions about preventive therapies such as statins. The headline finding is nuanced: CAC adds little for most people but can be a useful tiebreaker in patients with borderline or intermediate PREVENT risk.
The PREVENT equations estimate 10-year cardiovascular risk using standard clinical data — blood pressure, cholesterol, age, family history, and comorbid conditions (including inflammatory disease, diabetes, kidney disease, cancer, HIV, and some reproductive conditions). PREVENT classifies 10-year risk as: low (<3%), borderline (3–5%), intermediate (5–10%), and high (≥10%).
PREVENT underpins recent ACC-AHA guideline changes referenced in the studies. Those guidelines recommend considering incidental coronary calcium findings when advising statin therapy for men aged 40 and older and women aged 45 and older who have borderline or intermediate 10-year risk. The updated guidance expanded the role for CAC relative to the 2018 guidance, which had suggested CAC mainly for intermediate-risk individuals.
CAC scores typically range from 0 to over 1,000. Conventional interpretive bands described in the reporting include none at 0, mild under 100, moderate up to 300, and severe over 300. CAC is most often obtained with a dedicated coronary calcium CT scan, which is not routinely covered by insurance and may cost patients roughly $100 to $400. Research cited in the coverage found that CT scans performed for other indications — when they include the heart — detect coronary calcium and perform comparably to dedicated CAC scans for predicting 10-year coronary heart disease, cardiovascular disease, and mortality.
Both studies analyzed just over 6,000 participants aged 45 to 79 from MESA with 10-year follow-up. Investigators asked whether adding CAC to PREVENT risk scores improved prediction of later heart attacks, strokes, and deaths. Overall, adding CAC to PREVENT produced only modest improvements in statistical prediction when applied to the whole cohort.
However, in subgroup analyses the value of CAC was concentrated among people categorized by PREVENT as borderline or intermediate risk. In those groups, adding a calcium score led to greater reclassification — better identifying who later experienced events and who did not — than PREVENT alone.
Investigators and co-authors described CAC as most useful when PREVENT places a patient near treatment thresholds and the decision about starting a statin is uncertain. Michael Shapiro, a co-author on the JACC paper, summarized the takeaway: “CAC was most helpful as a tiebreaker when a patient was at borderline risk and the statin decision was unclear.” He also emphasized that CAC zero should not be used as an automatic veto against statin therapy. Nilay Shah, a co-author on the JAMA analysis, reported that CAC produced “much more substantial” reclassification among borderline and intermediate groups, improving identification of who later had a cardiovascular event within 10 years.
The JACC study also found examples where patients whose PREVENT risk exceeded 5% (qualifying them for statin treatment) still had events despite a CAC score of zero, highlighting that a zero CAC does not eliminate risk.
The studies support a guideline-centered, selective use of CAC in the PREVENT era. Key implications include:
Reserve CAC scanning primarily to clarify management for patients with borderline (3–5%) or intermediate (5–10%) PREVENT 10-year risk where the decision about statins is uncertain.
Do not use CAC universally; for most patients PREVENT alone provides adequate risk estimation and CAC adds only modest incremental predictive value.
A CAC of zero should not be treated as an absolute reason to avoid statin therapy, especially when PREVENT assigns higher absolute risk.
Incidental coronary calcium seen on CTs performed for other reasons can and should be incorporated into risk assessment when available, as those images perform comparably to dedicated scans for 10-year prediction.
Some patients request CAC scans because seeing an image of calcium in their coronary arteries can make the risk more tangible and may motivate preventive behaviors. CAC scans are typically out-of-pocket for patients, with reported costs around $100 to $400. The article notes growing interest in opportunistic screening using existing CT images and in artificial intelligence algorithms that can automate detection of coronary calcium on noncardiac CTs; such opportunistic use received a nod in ACC-AHA guidance.
Harlan Krumholz, commenting on the studies, suggested distinguishing the value of ordering a CAC test from the value of having the result: the information can have clinical and motivational value, even when it is unlikely to change the treatment decision.
The reporting emphasizes that the overall improvement in prediction when adding CAC to PREVENT across entire populations was modest. The detailed magnitude of statistical improvement for the whole cohort beyond qualitative descriptions was not exhaustively reported in the article. The studies focused on reclassification within the MESA cohort aged 45–79 followed for 10 years; applicability to younger patients or different populations was not addressed in the coverage. The article also highlights that CAC zero does not guarantee absence of future events, underlining residual risk despite a zero score.
Use PREVENT routinely to estimate 10-year cardiovascular risk and follow shared decision-making for preventive therapies.
Consider ordering a CAC scan, or using incidental coronary calcium detected on other CT imaging, when PREVENT places a patient in the borderline or intermediate risk range and the statin decision is unclear.
Avoid using a CAC of zero as an automatic reason to withhold statin therapy when PREVENT indicates significant absolute risk.
Discuss cost, potential benefits, and limitations of CAC with patients; explain that for most people the test will not change management.
Incorporate CAC results into patient conversations to help contextualize absolute risk and to guide intensity of preventive efforts.
These recent MESA-based analyses support a selective, guideline-aligned role for CAC: a targeted tool to refine risk near treatment thresholds rather than a universal screening test for everyone.