CAD in AF patients can be excluded with 320-detector computed tomography
MedWire News: Chinese researchers say that 320-detector computed tomography coronary angiography (CTCA) can exclude coronary artery disease (CAD) in patients with atrial fibrillation (AF).
Arrhythmia is generally considered a contraindication to CTCA because heart rate variations may lead to inappropriate data sampling and severe motion artifacts, say Zhaoqi Zhang (Capital Medical University, Beijing) and colleagues.
However, they add that 320-detector CT makes it possible to cover the whole heart in a single CT snapshot and eliminates "stair-step" artifacts inherent in 64-slice technology.
The team examined the ability of 32-detector CT coronary angiography to detect significant coronary stenoses in 37 patients with persistent AF and suspected CAD.
All patients underwent both 320-detector CTCA and conventional coronary angiography. CT image quality and the presence of significant stenoses (50% or greater luminal narrowing) was evaluated by two radiologists blinded to the conventional angiography results.
Of 474 coronary segments studied, the researchers report that 459 - or 96.8% - were diagnostically evaluable, and they add that the analysis of coronary artery stenosis showed "promising results."
On per-segment analysis, sensitivity was 90.0% (18 of 20), specificity was 99.3% (436 of 439), positive predictive value was 85.7% (18 of 21), and negative predictive value was 99.5% (436 of 438).
There was no significant difference between 320-detector CTCA and conventional coronary angiography in detecting significant stenosis. The mean effective dose of 320-detector CTCA was 13.0 mSv.
Reporting in the journal European Radiology, Zhang et al note that most patients studied had mitral valve disease and needed CAD to be ruled out before surgery, and that the sensitivity and specificity of CTCA may differ in AF patients with a higher prevalence of CAD.
Nonetheless, they conclude: "The high negative predictive value makes 320-detector CTCA a potential replacement for invasive coronary angiography in the care of patients with AF and structural heart disease who need CAD ruled out before surgery."
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By Anita Wilkinson