CAC scanning may be the most effective screening for coronary artery disease

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A review of five prospective, randomized clinical trials found that a coronary artery calcium (CAC) scan could be the most effective way to screen for coronary artery disease in asymptomatic patients.

The researchers noted that CAC scanning did not cost as much as other options, limited radiation exposure and has been proven to predict short- and long-term risk.

Lead researcher Alan Rozanski, MD, of Mount Sinai St. Luke’s Hospital and the Icahn School of Medicine at Mount Sinai in New York, and colleagues published their results online in JACC: Cardiovascular Imaging on March 6.

“There is now sufficient evidence to support the routine use of CAC scanning for screening in clinical practice,” Rozanski said in a news release. “Importantly, the CAC score has become one of our most robust predictors of patient risk. Patients are at very low risk when the CAC score is zero and at high risk when the CAC score is highly elevated. Any degree of CAC abnormality, however, even a CAC score of one or above, is sufficient reason for patients to adopt more heart-healthy behaviors.”

By 2030, the direct costs of cardiovascular healthcare are projected to triple to an estimated $818 billion, according to an American Heart Association (AHA) analysis that the researchers cited. Thus, they mentioned that it was important to develop a more effective strategy to prevent cardiovascular disease.

For years, physicians have assessed population-based cardiovascular disease risk factors to identify people who require more intense prevention efforts. Recently, though, more clinicians have used computed tomography (CT) imaging to determine whether people have atherosclerosis. The researchers noted that approximately 40 to 60 percent of people do not realize they have heart disease until they die or have an MI.

"By using imaging for screening, we can detect problems early on, which gives the patient an opportunity to make lifestyle changes to help avoid developing heart disease—such as by improving nutrition, starting to exercise or quitting smoking," Rozanski said in the news release. "We believe this will not only help improve and save lives but that it can ultimately contribute to lower health costs since the earlier adoption of positive health habits can reduce patients clinical risk and potentially eliminate the need for more costly interventions later on."

For this analysis, the researchers examined five imaging trials for the primary prevention of cardiovascular disease: the DIAD (Diagnostic Imaging in Asymptomatic Diabetics) trial, the St. Francis Heart Study, the PACC (Prospective Army Coronary Calcium) trial, the EISNER (Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research) trial and the FACTOR-64 study.

The trials had some limitations, according to the researchers, including that they were underpowered and the duration of follow-up was less than five years in each of the studies.

As of now, physicians still mostly use algorithms such as the Framingham Risk Score or the Pooled Cohort Equations to screen for coronary artery disease. However, the researchers noted that algorithms only predict the presence of underlying atherosclerosis and that imaging modalities could become more popular to screen for atherosclerosis.

Although the researchers noted that prospective imaging trials would likely not assess hard clinical events such as mortality, they recommended that future trials examine other endpoints such as whether imaging-guided medical therapy improves health behaviors, reduces risk factors and helps inform decisions on medication use. They added that trials could compare the cost-effectiveness of imaging-guided preventive care versus usual care.

“On a practical basis, both CAC scanning and ultra-sound could be used for screening assessments, but CAC scanning might be particularly attractive in this regard due to its ease of acquisition, low cost and radiation exposure; its proven ability to predict both short- and long-term risk; and the widespread and ease of understanding the 'CAC score' by clinicians (i.e., a single score that conveniently reflects the overall burden of coronary atherosclerosis),” the researchers wrote. “CAC scanning may also be beneficial because of its additional ability to ascertain which asymptomatic patients may benefit from subsequent stress testing due to the correlation between the magnitude of CAC abnormality and the likelihood of inducible myocardial ischemia.”