Plaque progression was slower in patients who were shown their CAC scores, an Australian study found.
Coronary artery calcium scores can significantly raise adherence to medication and slow the progression of plaque buildup in people at intermediate risk, an Australian study has found.
The CAUGHT-CAD trial (Coronary Artery Calcium Score: Use to Guide Management of Hereditary Coronary Artery Disease), published in JAMA, screened more than 1000 asymptomatic people with a family history of premature coronary artery disease and excluded anyone with a coronary artery calcium (CAC) score of zero or more than 400.
The remaining 449 (365 were ultimately analysed) were randomised to either usual care (guideline-based risk management) or CAC score-guided care: their results were explained to them using images, and they were prescribed 40mg atorvastatin. In the usual care group, the patients’ GPs were blinded to CAC score and statin prescription was rare as they were below the usual threshold for statin treatment.
After three years the CAC group had substantial reductions in LDL cholesterol (–51mg/dL compared with −2mg/dL for usual care), and while total plaque progression continued in both groups, the CAC group had significantly less progression (15.4mm3 vs 24.9mm3).
Noncalcified plaque, the more dangerous kind, was slightly reduced in the CAC group and increased in the usual care group (−0.8mm3 vs 4.5mm3).
Out of 179 CAC score-guided patients, 27 withdrew from their statin within the three years.
Co-author and cardiologist Professor Thomas Marwick, of the Baker and Menzies Institutes, said the usual dropout rate would be 50% within one year.
“This is saying that calcium scoring, in conjunction with the disease management program, changes the progression of disease, and that’s a very different discussion than we’ve seen before,” he told The Medical Republic.
“It’s not just gathering the images and getting the score. It is the process of using that to educate the patient which gave us a positive signal. Had we not given them calcium score-guided education, we would not have seen them adhere.”
Professor Marwick said showing the patient the image of their disease seemed far more effective than telling them numbers and probabilities. A calcium score, unlike other population-based risk factors, was a predictor for the individual.
“We sit down with patients all the time and give them their risk numbers, but that doesn’t have an impact on their adherence. Something is different here. We think it’s the process of showing, of giving a personalised message to the patient based on their image – they see that they’ve got disease – rather than ‘you’ve got a 20% risk at 10 years’.
“I think people find it a lot easier to have the inconvenience and minor cost of taking a daily statin if they know that they’re treating something, rather than knowing they’re treating a prospect of something which may or may not occur.”
Calcium score is a reclassification factor in the Australian CVD risk calculator, rather than a primary variable.
Professor Marwick said CAC scores were not a useful test for the entire population. What they could do was reclassify people of intermediate risk – namely those at around 0.5% to 2% risk of an event in the next five years per the calculator – into high or low risk, where treatment options were less fuzzy.
He said guideline groups were already taking an interest in the results.
“If somebody is at intermediate risk and they’ve got calcium, then I think the evidence points towards [a GP] saying to the patient: if we start on the statin, there’s evidence that we could change the trajectory of your plaque deposition.
“The people that are holding out against it say that they want to see an outcome study, and I don’t think that outcome study will ever be done, because it would be huge and it would require a very long follow-up … I think that this is the closest that we’re going to get to evidence that we can change the trajectory of the disease. In my opinion, this should be used for changing the guidelines.”
Professor Garry Jennings, chief medical advisor and interim CEO of the Heart Foundation, said while this was “a great study”, it was not enough to change practice.
“It showed that people are incentivised by being shown the result of their coronary score,” Professor Jennings told TMR.
“In that sense, it doesn’t make a case for coronary calcium scoring by itself, because that also depends on cost-effectiveness. And absolutely nobody is suggesting coronary scores for everyone. But it does suggest [a CAC score] does help people understand the need for them to engage properly with the advice they’re being given. So, a useful study, but it doesn’t change the game.”
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Professor Jennings said there was good international consensus that in people at intermediate risk, for whom there was uncertainty around long-term statin therapy, calcium scoring could help decision making.
There was also a need for better risk communication – “Just telling people some numbers isn’t enough” – but whether that required an additional test was still a question.
“There’s no doubt people respond to being shown pictures or real figures of themselves rather than numbers they may not necessarily understand,” he said. “So I kind of agree – it’s just whether that’s the only way to achieve the same result.”
There was still a lack of consensus over the risk of overdiagnosis and overtreatment, he said, but there were groups who should probably not receive a calcium test: young people, who may be falsely reassured; older people, who are almost certain to have some calcium; and people already on statins, for whom it won’t change anything.
By way of advice to GPs, Professor Jennings said to “watch this space, because there are some significant trials coming out”, and to use calcium as a reclassification tool as recommended in the 2023 guidelines.
