Randomized controlled trials needed to increase use of CAC scoring
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Coronary artery calcium scoring can be used as a decision aid, although more trials are needed for guidelines to endorse its use as a class IA recommendation, according to a presentation at Society of Cardiovascular Computed Tomography Annual Scientific Meeting.
During his presentation, Michael D. Shapiro, DO, Fred M. Parrish Professor of Cardiology and Molecular Medicine and director of the Center for Prevention and Cardiovascular Disease at Wake Forest University School of Medicine, said that these trials have established the ability of coronary artery calcium (CAC) scoring to detect early subclinical atherosclerosis, in addition to its safety, reproducibility, prognosis, incremental value and cost effectiveness, yet there are not enough robust data from randomized controlled trials.
“We do have some randomized data, some small studies, but I think what everybody’s really interested in is the large cardiovascular outcomes trial,” Shapiro said. “It’s important to understand that our thinking of coronary calcium has really evolved significantly.”
Data on coronary calcium scoring
In a study published in the Journal of the American College of Cardiology in 2015, researchers found that nearly half of patients in the intermediate risk group for 10-year atherosclerotic CVD would have a CAC score of 0 and fell below the threshold for a statin recommendation.
Shapiro said that these findings had a major influence on guideline committees, as shown over the last 2 years with the release of the 2018 Multi-Society Cholesterol Clinical Practice Guidelines and the 2019 American College of Cardiology/American Heart Association Guideline on the Primary Prevention of Cardiovascular Disease. In particular, the 2018 guideline recommends the consideration of coronary calcium testing to enhance risk prediction and to aid in management decisions. This can be especially helpful for patients for whom a risk decision is uncertain.
“We have a much more specific role for calcium testing now,” Shapiro said. “It’s not really thought of as a screening test as it had been in earlier days, but rather a test that helps us to refine risk estimates in those who might meet criteria for statin therapy and really facilitate the shared decision-making process between patient and provider.”
Although there are available data to support the use of coronary calcium scoring, barriers persist for its increased use.
Risk assessment is often performed by primary care rather than cardiology. Primary care represents a huge area in medicine, with approximately 550,000 providers that fall within several categories within the specialty, he said, noting that each category within primary care has its own professional society which may sometimes disagree with what a cardiology society recommends. For example, the American Association of Family Physicians (AAFP) disagreed with some tenets espoused by the ACC/AHA cholesterol guidelines. One area of contention within these guidelines was the use of CAC scoring; although the ACC/AHA said it was a reasonable tool, the AAFP said the current evidence is insufficient to assess the benefits and harms of using this tool.
“We need to keep in mind that as professional societies, we’re not speaking in one voice, and that is something very important as a barrier,” Shapiro said.
Other barriers to the use of coronary calcium testing include insurance coverage, equal access to care, provider inertia and both patient and clinician education. Some payers are starting to cover CAC scoring, though insurance coverage remains poor in this area. This lack of coverage can lead to undertherapy when therapy is indicated and overtreatment for patients with a calcium score of 0, Shapiro said.
He noted this lack of coverage necessitated the use of self-paid programs, which is typically used by patients with higher socioeconomic status and does not reflect the entire population.
“The high out-of-pocket expenses limits access to those who don’t have those financial resources,” Shapiro said. “We know that increased out-of-pocket expenses for evidence-based therapies disproportionally affects minority populations and worsens racial and ethnic disparities.”
Ongoing CV outcomes trials
With regards to CV outcomes trials focused on CAC scoring, there have been attempts to reach out to the NIH to fund a large randomized controlled trial, but it was thought to be too challenging.
“We have to remember that when we’re talking about coronary calcium in primary prevention, we’re looking at a very low-risk population, so the number of patients and the amount of follow-up that would be required to see a difference in events over time is enormous,” Shapiro said. “This makes it very expensive and very complex. There are also some potential ethnical issues as well.”
Despite these challenges, there are two large randomized controlled trials on coronary calcium scoring in Europe: the Danish Cardiovascular Screening Trial and the ROBINSCA trial. Both trials are comparing coronary calcium scoring with standard of care.
“The ongoing cardiovascular outcomes trials will decide the fate of further guideline recommendations,” Shapiro said.
Reference:
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Shapiro MD. Cardiovascular CT in 2020: Current Developments, Guidelines and Trials. Presented at: Society of Cardiovascular Computed Tomography Annual Scientific Meeting; July 17-18, 2020 (virtual meeting).
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