Calcium Scans Add Little to PREVENT Calculator Overall, but Sharpen Statin Decisions in Borderline Risk
核心洞察
Two studies following over 6,000 adults for 10 years found coronary artery calcium scores only modestly improved cardiovascular risk prediction when added to the PREVENT (搜索) calculator.
In patients classified as borderline or intermediate risk by PREVENT (搜索), calcium scoring produced more meaningful reclassification of who would and would not have a heart attack or stroke.
Researchers cautioned that routine calcium scanning in low-risk people brings unnecessary radiation, testing and costs, while high-risk patients should start statins (搜索) regardless of scan results.
Adding a coronary artery calcium (CAC) score to the American Heart Association's PREVENT (搜索) risk calculator yields only a modest improvement in predicting heart attacks and strokes across the general population, but provides clinically meaningful refinement for patients whose initial risk estimate falls in the borderline or intermediate range, according to two studies published in August.
The findings, drawn from more than 6,000 adults followed for a decade in the Multi-Ethnic Study of Atherosclerosis (MESA), address a practical question facing preventive cardiologists: when does a calcium scan actually change what a clinician does?
Modest Gains Overall, Larger Gains in the Middle
Participants ages 45 to 79 received both a CAC score and a PREVENT (搜索) estimate of their 10-year cardiovascular risk at the start of the study. Over the following decade, 6% experienced a heart attack or stroke.
When researchers compared predictions that incorporated calcium scores against those based on PREVENT (搜索) alone, the model's discrimination — its ability to separate people who would have an event from those who would not — rose only slightly, from 0.73 to 0.75.
The picture shifted in a secondary analysis restricted to participants whose PREVENT (搜索) scores placed them at borderline or intermediate risk, defined in the JAMA study as a 3% to 9% 10-year risk. In that group, adding the calcium score produced a substantially larger reclassification.
"You get a much more substantial, quote, 'reclassification,' meaning people who were in the borderline and intermediate risk category, when they got a calcium score," said Nilay Shah, a preventive cardiologist at Northwestern University Feinberg School of Medicine and co-author of the JAMA study, in an interview with STAT. "We much better identified those who had a heart disease event later, within the next 10 years, and we much better identified those who didn't have a heart disease event in the next 10 years."
"For patients at borderline risk, knowing their calcium score can help determine whether their risk is actually lower or higher than initially estimated, which can help guide treatment decisions," Shah said.
The JAMA study, titled "Predictive Utility of Coronary Artery Calcium Added to the PREVENT (搜索) Atherosclerotic Cardiovascular Disease (搜索) Equations," was published Aug. 26. It was supported by the American Heart Association (grant 24CDA1266732) and the National Heart, Lung, and Blood Institute.
A Tiebreaker, Not a Veto
A companion analysis published Aug. 18 in the Journal of the American College of Cardiology (搜索) reached a similar conclusion. Michael Shapiro, a preventive cardiologist at Wake Forest University School of Medicine (搜索) and co-author of that study, framed the result in terms of the statin conversation.
"Adding CAC to PREVENT (搜索) for everybody only modestly improves statistical prediction," Shapiro told STAT via email. "The main message is that not everyone needs a CAC scan and CAC zero should not be used as a veto against statin therapy. CAC was most helpful as a tiebreaker when a patient was at borderline risk and the statin decision was unclear."
In the JACC study, some patients who qualified for statin treatment because their PREVENT (搜索) risk was 5% or higher went on to have heart attacks, strokes or other events despite a CAC reading of zero.
"CAC may still help explain risk, improve adherence, and guide how intensive prevention should be, but generally should not be used to avoid treatment," Shapiro said. "Our findings support a guideline-centered role for CAC in the PREVENT (搜索) era. Mainly, refining risk near the treatment thresholds, helping put absolute risk into context, and informing the intensity of preventive efforts."
Weighing the Downsides of Testing
Shah also highlighted the costs of scanning patients whose treatment would not change. "Routinely using a calcium scan in people who are at low risk may result in unnecessary radiation exposure, testing and costs with unclear clinical benefits," he said. "Using calcium scans in people who are at high risk is likely to result in unnecessary testing because these individuals are recommended to start a statin regardless of what the calcium scan shows."
CAC scans are not typically covered by insurance and can cost patients $100 to $400, according to STAT. PREVENT (搜索), by contrast, relies on standard information gathered during a doctor's visit, including blood pressure, cholesterol, age, sex, family history and conditions such as inflammatory disease, diabetes, kidney disease, cancer, HIV and certain reproductive conditions.
The PREVENT (搜索) equations classify 10-year risk as low (under 3%), borderline (3% to 5%), intermediate (5% to 10%) and high (10% or higher). CAC scores range from 0 to 1,000 or higher, with risk climbing from none at 0 to mild under 100, moderate up to 300 and severe over 300.
The American College of Cardiology (搜索) and American Heart Association guidelines issued earlier this year recommend using incidental calcium findings to inform statin decisions for men age 40 and older and women age 45 and older living with borderline or intermediate 10-year risk — an expansion from the 2018 guidelines, which suggested them only for people at intermediate risk. The guidelines also say clinician-patient discussions about statins (搜索) should begin as early as age 30.
Separately, research published in Circulation in July concluded that CT scans performed for other reasons predicted coronary heart disease, cardiovascular disease (搜索) and deaths over the next 10 years just as well as CAC-specific scans, since the images can reveal calcium deposits stiffening the arteries regardless of the original indication.
Incorporating Existing Scores and Remaining Questions
Harlan Krumholz, a cardiologist and health outcomes researcher at Yale University (搜索) who was not involved in the studies, told STAT that existing calcium scores should still be folded into risk assessment. He distinguished between the decision to order a test and the value of knowing its result.
"I would distinguish the value of ordering the test from the value of knowing the result," Krumholz said. "These studies help us be more disciplined about when to order CAC solely to resolve a treatment decision."
Shah suggested that patient interest in the scans may be driven partly by their tangibility. "We can estimate somebody's risk with a calculator, and you get a number," he said. "Or you can actually see an image of your heart and say, OK, that's actually what's going on in my heart. I think that appeals to a lot of people because it's much more tangible." STAT also noted that interest may be growing amid artificial intelligence-based algorithms that automate opportunistic screening, which received a nod in the March ACC-AHA guidelines.
The researchers said further studies are needed to determine how much calcium scores improve PREVENT (搜索) estimates in specific populations, including higher-risk groups such as South Asian and Filipino adults. Additional research is also needed in younger people, since MESA participants were between ages 45 and 79 when the study began.
Cardiovascular disease (搜索) affects about 10% of U.S. adults age 30 to 79 and remains the nation's leading cause of death, yet many heart attacks and strokes are preventable, Shah said. The results also support the clinical usefulness of the relatively new PREVENT (搜索) calculator, which performed well even without calcium scan results.
"The findings help us understand how best to use the available tools to estimate someone's risk of a heart attack or stroke," Shah said. "That provides more precise guidance for who is most likely to benefit from using a statin to help prevent (搜索) heart disease."