Assessment of coronary anatomy prior to Transcatheter Aortic Valve Replacement has great prognostic significance. Invasive coronary angiography is done prior to TAVR though CT coronary angiography has a role in ruling out coronary artery disease in those with low or intermediate pretest probabilities. Accurate interpretation of coronary arteries in those planned for TAVR has challenges because of high occurrence of abnormal heart rhythm, contraindications for beta blockers and nitroglycerine administraton.
Still important is the blooming artifacts on CT coronary angiography in those with coronary stents or severe calcification. Blooming artifacts can lead to overestimation of stenosis and a false positive result. This can be overcome by the new photon counting detectors which enable ECG gated ultrahigh resolution CT coronary angiography.
Ultrahigh resolution CT coronary angiography has excellent image quality and vessel sharpness with reduced calcium induced blooming in patients with high amount of coronary calcium. It is also useful in those with implanted coronary stents. A study evaluated 68 patients with severe aortic stenosis planned for TAVR with ultrahigh resolution CT coronary angiography and compared with invasive coronary angiography.
Agatston score of 1000 or more was there in 24 patients and 15 had coronary stents. Overall image quality was reported as excellent. Authors concluded that ultrahigh resolution photon counting CT coronary angiography provided high diagnostic accuracy in detection of CAD in this high risk poplation, including subjects with severe coronary calcification and coronary stents. This new technology could be useful in avoiding invasive coronary angiography in patients planned for TAVR in future, if more studies in wider spectrum of populations confirm these findings.
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