Computed tomography coronary angiography (CTCA) could be used to define the optimal fluoroscopic viewing angles of the coronary arteries to assist operators with coronary angiography and staged PCI procedures, according to findings from a study presented during EuroPCR's e-Course 2020 and simultaneously published in JACC: Cardiovascular Interventions.

Viktor Kočka, MD, PhD, and colleagues sought to provide a scientific basis, rather than the historical empirical approach, for using 3D multislice CTCA to determine the optimal viewing angles of the left and right coronary artery ostia and proximal coronary bifurcations. They conducted a retrospective analysis of 100 CTCA scans of consecutive patients for suspected coronary artery disease at a single center in Prague, Czech Republic.

Two of 100 MSCT scans were not included in the analysis due to poor image quality. Coronary distribution was right dominant in 77 patients (79%), left dominant in 15 patients (15%) and codominant in six patients (6%). No significant associations were found between the heart axis and coronary artery structures (all correlation coefficients <0.5).

The results showed that for ostial left main stenting, the average optimal viewing angle was 37 for the left anterior oblique (LAO) and 22 for the caudal view. For ostial right coronary stenting, it was LAO 79 and CRA 41. The average optimal fluoroscopic viewing to mitigate foreshortening of the proximal left main up to 8 mm was LAO 1 and CRA 37. The analysis showed that in approximately 70% of patients it would be possible to achieve practical views for ostial and proximal left main stenting.

The estimated mean optimal viewing angles for bifurcation stenting were: left main, LAO 0 and CAU 49; left anterior descending with first diagonal branch, LAO 11 and CRA 71; left circumflex bifurcation with first marginal branch, LAO 24 and CAU 33; and posterior descending artery and posterolateral branch, LAO 44 and CRA 34.

According to the authors, this is a novel method to define optimal viewing angles of coronary arteries which could modify the standard coronary angiography projections. However, the researchers note that not all CTCA-defined fluoroscopic viewing angles are practical or achievable with existing C-arm equipment. Furthermore, across patients, optimal fluoroscopic viewing angles for coronary ostia and bifurcations are highly variable despite a reproducible methodology.

They write, "Given the increasing use of CTCA for diagnostic and prognostic purposes, the proposed approach could be integrated in the usual workflow and provide patient-specific, individualized information to PCI operators." Future efforts should focus on studies assessing the agreement between predicted tomographic optimal viewing angles and invasive angiography and the impact it may have on clinical outcomes.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Atherosclerotic Disease (CAD/PAD), Interventions and Coronary Artery Disease, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: Coronary Angiography, Coronary Artery Disease, Retrospective Studies, Percutaneous Coronary Intervention, Tomography, Tomography, X-Ray, Fluoroscopy

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