Half a million men and women who might otherwise be subject to more expensive and invasive angiograms to detect coronary artery stenosis now have a new option: coronary computed tomographic angiography (CCTA).

Traditional coronary angiography assesses plaque build up, which can cause arteries to narrow, resulting in coronary artery disease. During coronary angiography, dye is injected into the bloodstream via cardiac catheterization — the insertion of a long, thin, flexible catheter into the arm, groin or neck. The tube is then threaded into the coronary arteries and dye is injected. This procedure typically requires a day at the hospital.

CCTA is not invasive, takes just 30 minutes and is far less expensive. While the technology has been around for several years, there has been a lack of evidence to prove it's a viable option.

But the new study, the first the check the accuracy of CCTA compared to the standard coronary angiography, found that CCTA was 99% as effective in ruling out obstructive coronary artery stenosis or narrowing of these arteries.

The study, which was funded by GE Healthcare (Waukesha, Wisconsin) and used the company's LightSpeed VCT (volume computed tomography), found CCTA provided high diagnostic accuracy for detection of obstructive coronary stenosis at the thresholds of a 50% narrowing and at 70% stenosis.

"This gives cardiologists a better opportunity to evaluate patients," Matthew Budoff, MD, told Diagnostics & Imaging Week. He's a principal investigator at the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center (Torrance, California) and lead author of the current study, which was conducted at 16 sites with 230 research volunteers who had chest pain but no known coronary artery disease.

"First and foremost, it allows for non-invasive angiograms," Budoff said. "We can see the percent of stenosis without going into to the cardiac cath lab. We can also see the mild plaque that may be present, which is often missed by nuclear imaging or stress treadmill testing. And, we can see plaque composition to determine if it's lipid laden or calcified. We can also look at heart chambers and the function of the heart with CCTA."

The trial, Assessment by Coronary Computed Tomographic Angiography of Individuals Undergoing Invasive Coronary Angiography (ACCURACY), prospectively evaluated subjects with chest pain who were clinically referred for invasive coronary angiography. Each of the research volunteers were examined using the electrocardiographically gated 64-multidetector row CCTA. Each volunteer also underwent the more expensive and invasive coronary angiography.

On a patient-based model, the sensitivity, specificity, and positive and negative predictive values to detect =50% or =70% stenosis were 95%, 83%, 64%, and 99%, respectively, and 94%, 83%, 48%, 99%, respectively.

"Our results show that it's highly accurate compared to invasive angiography," Budoff said, "and the advantages are pretty significant." The cost of CCTA is about 10% that of invasive angiography. It takes about 30 minutes, compared to invasive angiograms which require patients to be at the hospital or imaging center all day.

Budoff said reimbursement already is in place with Medicare and several private insurers.

Another study, reported earlier this year, showed that patients who underwent CCTA, without a prior diagnosis of CAD, incurred costs $603 lower (per-patient average) than those who underwent myocardial perfusion imaging (MPI or SPECT). Both groups had equal clinical outcomes. Patients with known CAD who underwent MPI incurred healthcare costs $2,451 lower (per patient) than CCTA patients with equal clinical outcomes, suggesting that CCTA may be a cost-efficient alternative in patients without a prior CAD diagnosis.

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