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New CT Scanners Detect Blocked Arteries
December 18, 2015
A new international study found that while a new generation of faster computed tomography (CT) scanners easily and correctly identified people with blocked arteries, they were not accurate enough compared to the conventional coronary angiography.
The study was led by senior investigator and cardiologist Dr João Lima, who is a professor of medicine and radiology at The Johns Hopkins University School of Medicine and its Heart and Vascular Institute in Baltimore, Maryland, USA, and was published in the 27 November online issue of the New England Journal of Medicine, NEJM. Altogether, researchers from nine medical centers in the US, Brazil, Germany, Japan, Canada, Singapore and the Netherlands worked on the study.
Lima and colleagues concluded that while conventional catheterization was still the gold standard for diagnosing coronary artery blockages, the newer more powerful 64-row CT scanner is proving to be a close second. The study may well allay fears that CT scanners are a costly tool for this type of diagnosis.
The researchers said that although the new and faster 64-row CT scanners were only 93 per cent as precise as cardiac catheterization at pinpointing blocked arteries, they were 100 per cent accurate at identifying which people had them and which did not.
Blocked coronary arteries put people at high risk of heart attack because they can restrict blood flow. Once diagnosed, patients can then have cardiac bypass surgery or angioplasty (where the artery is widened using a small balloon that is inflated after being inserted in the affected blood vessel) to restore their blood flow.
Over 250,000 people have a coronary bypass in the US every year, and another 1.2 million undergo angioplasty.
Lima and colleagues compared the results of CT scans and catheterization, and found they were equally useful at predicting the need for bypass surgery and angioplasty in patients who had shown heart attack symptoms, for instance shortness of breath and pains in the chest. The CT scans predicted 84 per cent and the catheterization predicted 82 per cent of the invasive procedures performed.
While not advocating that the new 64-CT replaces catheterization as a diagnostic tool, Lima pointed out that it takes only 5 to 10 seconds to carry out a scan, making it a useful alternative to help doctors "rule in or rule out" coronary blockages, when other tests, such as the cardiac stress test, might be unclear or unsafe for certain patients.