CAC scores not always reliable for ruling out obstructive CAD
Coronary artery calcium (CAC) scores of zero may help rule out obstructive coronary artery disease (CAD) among older patients, according to a new analysis published in JAMA Cardiology. When assessing younger patients, however, CAD may still be very well be present.
“Although several studies have reported an overall low prevalence of obstructive CAD in symptomatic patients without CAC, it is unknown whether this finding is true across all age groups and in men and women separately,” wrote lead author Martin Bødtker Mortensen, MD, PhD, a cardiologist at Aarhus University Hospital in Denmark, and colleagues. “Because early atherosclerotic lesions are often noncalcified, the ability of CAC to rule out obstructive CAD may be dependent on age. Such information would help in understanding the appropriate use of CAC in the diagnostic workup of symptomatic patients.”
The team examined data from more than 23,000 adult patients who underwent computed tomography angiography (CTA) from 2008 to 2017 in Denmark. All patients presented with symptoms that suggested they may have CAD.
Overall, 54% of patients had a CAC score of zero. Among that group, it was determined that 6% did have obstructive CAD.
Looking just at patients with a CAC score of zero, obstructive CAD was seen in 3% of patients younger than 40, 5% of patients between the ages of 40 to 49, 6% of patients between the ages of 50 to 59, 6% of patients between the ages of 60 to 69 and 8% of patients 70 years old and older.
“Similar results were found in men and women separately,” the authors added.
Looking at the relationship from another angle, the group found that 14% of patients with obstructive CAD had a CAC score of zero. This became less and less common as patients got older—while 58% of patients younger than 40 had a CAC score of zero and obstructive CAD, the same occurrence was true in just 5% of patients 70 years old and older.
“Although patients with a CAC score of zero generally had a low prevalence of obstructive CAD, ranging from 3% to 8% across different age groups, a substantial proportion of patients with obstructive CAD at a younger age had a CAC score of zero,” the authors wrote. “The explanation for this apparent paradox is that early atherosclerotic lesions are usually noncalcified. The added diagnostic value of knowing a CAC score of zero is highly dependent on age, with less value for younger than for older patients.”
Read the full study here.
Michael has more than 18 years of experience as a professional writer and editor. He has written at length about cardiology, radiology, artificial intelligence and other key healthcare topics.