Latest research suggests the tool instead increases the risk of overdiagnosis and overtreatment.
Adding coronary artery calcium scans to traditional risk scores provides no clinical benefit in assessing a patient’s cardiovascular status and risk, researchers have found.
The systematic review, published in JAMA Internal Medicine, found that while the scans might provide some additional information beyond traditional risk factors, it was unclear whether this translated into fewer heart attacks and strokes for people who took the test.
Lead author and epidemiologist, Associate Professor Katy Bell of Sydney University, said coronary artery calcium scans also created the risk of overdiagnosis and overtreatment in some patients.
“There’s indications that people who would seem to be low risk are receiving maybe more treatment than they need to have,” she told The Medical Republic.
“So, it seems like we’ve perhaps got a bit distracted by this new shiny test. If you look carefully at all the guidelines, including the cardiac society’s, even where they’re saying that the scans might be useful, they are careful to say it should be only if you’re unsure on the basis of the traditional risk assessment.”
The researchers identified six eligible cohort studies from the US, the Netherlands, Germany and South Korea. They looked at patients who had undergone one of the traditional cardiovascular disease (CVD) risk calculators recommended by national guidelines (including the Framingham Risk Score, QRISK, pooled cohort equation, NZ PREDICT, NORRISK, or SCORE) and assessed and reported incremental discrimination with coronary artery calcium scans for estimating the risk of a future cardiovascular event
Coronary artery calcium scans appeared to add modest value to the prognostic value of standard CVD risk calculators, but the researchers found the clinical value for changing clinical decisions about whom to treat, and potential benefits from this, appeared small.
In the study, 85.5% to 96.4% of people classified as low risk by the risk score, who were reclassified as intermediate or high risk by a coronary artery calcium scan, did not have a CVD event during five-to-10-year follow-up.
“There is currently no direct evidence that adding coronary artery calcium score information to traditional risk factors provides clinical benefit,” Professor Bell said.
She said any small and uncertain benefits might often be outweighed by harms – which included the potential to cause a cascade of unnecessary tests, diagnoses and treatments – from incidental findings, both cardiac and non-cardiac, such as small lung nodules, and risks from radiation exposure.
“There are also significant financial and opportunity costs to patients, clinicians and healthcare systems,” she said.
She said the groups most likely to benefit from coronary artery calcium scans were patients for whom, after standard CVD risk score assessment, there was reasonable likelihood that coronary artery calcium scans could help in clarifying whether the risk was high enough to justify primary prevention medications.
“But exactly which patients would benefit is currently unclear,” she said.
Coronary artery calcium scans hit the headlines following the death of Australian cricket legend Shane Warne, reportedly from a heart attack, while he was holidaying with friends in March. His death came about a week after another cricket great, Rod Marsh, died from cardiac arrest. Warne was 52 and Marsh was 74.
Writing in SwitzerDaily, Sydney cardiologist Dr Ross Walker, a vocal proponent coronary artery calcium scans, said he saw both tragedies as “a timely reminder to all of us that the best treatment of all modern diseases is not to get them in the first place; that is, prevention”.
“Almost all cardiovascular disease can be prevented if detected early and there are now very accurate cardiovascular screening tests that are available freely to us all that can detect early disease with preventative management, if necessary, commenced immediately,” Dr Walker wrote.
“Coronary artery calcium scoring (only in patients without a prior history of heart disease) is the most accurate predictor of cardiac risk. Coronary calcium scoring provides a picture of the coronary arteries, which is a surrogate marker for the accumulation of fat in the arteries over the decades up to the point of scanning. The great value is that coronary calcium scoring is quantitative.”
Attempts by TMR to contact Dr Walker to discuss the JAMA research were unsuccessful.
Professor Bell said she did not know the specifics of changing Shane Warnes’ medical history but understood that he was at least a smoker.
“And it seemed like maybe he had at least a couple of risk factors and, and maybe, based on a traditional risk assessment and the Framingham score or any of those traditional scores, he would have come out as a higher risk,” she said.
“I don’t know whether he was on preventative treatment already and what else could have been done, but it seems unlikely the calcium scan would have been necessarily that helpful in his case.”
Professor Bell said she hoped the JAMA piece would remind the public and GPs “that actually we do have really good evidence already about these, like traditional risk factors and risk scores. And we’re not actually making good use of those”.
She said it was important to measure traditional risk factors and using standard CVD risk calculators to estimate absolute risk.
“Currently many patients attending a GP are not having all risk factors measured, and of those that do, there is evidence of potential undertreatment of those at high risk, and overtreatment of those at low risk,” she said.
“So, the first thing is to measure and communicate the patient’s absolute risk based on traditional risk factors, using a shared decision-making approach and decision support tools that are available – for example, online decision aids.”
A shared decision-making approach was also needed on whether to have a coronary artery calcium scan – including clear communication about both potential benefits and potential harms of having a scan.
