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Cardiac CT Angiography: What is it? When do I order it?

Director of the cardiac CT program at Oklahoma Heart Institute Dr. Victor Cheng joins us on the blog today to talk about the program and when patients should be referred for a scan.

Cardiac computed tomographic angiography (CTA) is special CT scan that images the entire heart when heart structures are relatively still. A steady heart rate of less than 60 beats per minute will provide the best possible image quality in most patients. Oklahoma Heart Institute began a dedicated Cardiac CT program in June 2013. This program uses the CTA, which is based on echocardiograms and is enhanced with contrast.The ideal patient for cardiac CTA at OHI has a resting heart rate less than 100 beats per minute, no problems taking metoprolol (used to temporarily lower heart rate), ability to hold a breath for 12 seconds, normal renal function, and body-mass index less than 40 kg/m2.

Clinical cardiac CTA use is expanding. Applications of cardiac CTA can be broadly separated into non-coronary artery disease (CAD) related and coronary artery disease. For non-CAD situations, CTA is the preferred test to: 1) evaluate the left atrium and pulmonary veins in preparation for left atrial electrophysiologic procedures, 2) evaluate the left ventricular outflow tract and aorta in preparation for transcatheter aortic valve replacement, 3) determine heart and aorta anatomy before re-do cardiac surgery, 4) detect coronary artery anomaly, and 5) simultaneously evaluate the aorta and coronary arteries for disease.

Use of cardiac CTA to detect coronary artery disease in symptomatic patients at low or intermediate clinical pre-test probability continues to increase. Compared to other noninvasive tests, cardiac CTA has the highest proven sensitivity (95 percent or higher) and negative predictive value (95 percent or higher) for identifying native coronary artery blockage in patients without prior bypass surgery or coronary artery stenting, and should be preferred over other tests when patient characteristics are ideal (good heart rate, can hold breath, not extremely obese, normal renal function). Cardiac CTA is additionally advantageous when prior stress testing did not satisfactorily resolve the possibility of stenotic coronary artery disease, when stress testing accuracy is reduced (for example: left bundle branch block), and in minimizing radiation exposure in young patients for whom exercise testing is not favorable or possible.