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Preablation CT angiography may also spot CAD in AF patients

ORLANDO, FL — Although coronary CT angiography to assess the left atrium and pulmonary veins prior to ablation for atrial fibrillation (AF) is commonly considered not to be as good as a coronary angiogram would be for ruling in or ruling out stenotic coronary artery disease (CAD), a single-center study reports that in a handful of cases, CT scans revealed major incidental stenotic disease that led to important treatment changes[1].

Dr Victor Cheng (Oklahoma Heart Institute, Tulsa) presented the study findings at a poster session at the Society of Cardiovascular Computed Tomography (SCCT) 2016 Annual Scientific Meeting.

In some cases, a CT scan "allows adequate visualization of the coronary arteries, such that the reader can feel confident about detecting severe disease, and when that happens, a not-insubstantial number of patients end up getting their treatment changed," he told  heartwire from Medscape.

But it depends on how the cardiac CT angiography scan is done prior to ablation in AF patients, in a particular institution, poster moderator Dr Quynh A Truong (Weill Cornell Medical College, New York, NY) argued. They do these scans differently at her center, she told heartwire.

Moreover, "I see a potential for harm," she told Cheng. "It's a high radiation dose [3 mSv] and I don't necessarily agree that you're going to have great diagnostic accuracy," and it may lead to unnecessary invasive testing, she said. "I think if there is concern for CAD, [clinicians should] order a coronary CT," Cheng maintained.

On the contrary, the study showed that under very poor conditions for visualizing coronary artery patency, dual-source imaging still managed to conclusively identify disease in some people, Cheng rebutted. "When CT images that incidentally demonstrate potentially severe coronary artery disease are trustworthy, I feel compelled to comment on the finding and raise awareness for the patient's care providers," he said. "It is what I would want if I were the patient."

Coauthor Dr Roger D Des Prez (Oklahoma Heart Institute) concurred. "This is a diagnostic opportunity that is not zero," he said. But it's a very small number of patients, he conceded.

Frequency and consequences of incidental CAD stenosis on coronary CTA

Contrast-enhanced end-ventricular-systolic acquisition, without any prescan medication, is used to capture the maximum left atrial size in a CT angiography scan of the left atrium and pulmonary vein, and in some cases, the operator sees suspected stenotic CAD, Cheng explained. The researchers aimed to see whether there was any change in subsequent patient care when the operators reported that images of the left atrium and pulmonary veins also showed "suspected stenotic disease."

They reviewed data from 423 consecutive patients (240 men) who had never had a CAD event and underwent dual-source contrast-enhanced coronary CTA for left atrial and pulmonary vein assessment prior to AF ablation at their center. The patients had a median age of 66 and a median BMI of 31 kg/m2. They were exposed to an estimated median radiation dose of 3.1 mSv, which is still relatively low, according to Cheng and Des Prez.

The images were acquired without prescan heart-rate control or nitroglycerin; 137 patients were in AF and 77 had a maximum heart rate ≥100 during imaging.

Experienced readers reviewed the images at end-systole and they reported CAD only when there was a high suspicion of stenotic disease in at least one major coronary artery segment.

The image quality was sufficient to demonstrate important stenotic disease in at least one major segment or exclude such disease in all major segments in 240 patients.

Of these 240 patients, 27 patients (10%) had a major coronary artery segment with at least 50% stenosis and 13 patients (5%) had a major coronary artery segment with at least 70% stenosis.

This led to the cancellation of planned ablations in two patients (one underwent CABG and surgical pulmonary vein isolation).

Seven of the 13 patients with >70% stenosis in at least one major segment detected on the coronary CT scan went on to have coronary catheterization that confirmed major stenotic disease in four patients. Two patients then had percutaneous coronary artery stenting, and flecainide therapy was halted in two patients.

Thus, even under unfavorable conditions for imaging the coronary arteries, "we found that end-systole imaging still managed to diagnose de novo, treatment-altering stenotic CAD in a minority of patients" undergoing coronary CT assessment prior to ablation for AF, Cheng summarized.

"I don't doubt that this is useful in certain patients, but it shouldn't be done as routine," Truong said, and other centers may have different techniques and protocols.

Cheng agreed that these are rare cases when incidental major CAD is detected and reported, which can lead to further tests and altered treatment.

Cheng and Des Prez have no relevant financial relationships. Truong receives research grants from QI Imaging and is a consultant for the American College of Radiology and Aralez Pharmaceuticals.

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References

  1. Cheng V, Des Prez R, Auerbach E, et al. Clinical relevance of reporting major coronary segment stenotic disease from prospectively acquired end-systolic contrast-enhanced CT imaging intended for left atrial and pulmonary vein assessment before ablation to treat atrial fibrillation. Society of Cardiovascular Computed Tomography 2016 Annual Scientific Meeting; June 25, 2016; Orlando, FL. Abstract 72.

 

Source : Heartwire from Medscape © 2016  Medscape, LLC