Prediction of fluoroscopic angulation and coronary sinus location by CT in the context of transcatheter mitral valve implantation

Background: We sought to determine if preprocedural CT can predict appropriate fluoroscopic angulations to achieve a coplanar view during transcatheter mitral valve implantation (TMVI) and to assess the relationship of the mitral annulus and the coronary sinus to determine the feasibility of using this as an additional landmark on fluoroscopy. Methods: With CT, the mitral annulus was segmented in 25 patients with functional mitral regurgitation. After this, optimal projection curves were plotted and the necessary angulations for specific views parallel to the trigone-to-trigone line (TT view) and septal-to-lateral distance (SL view) were noted. The outer contour of the coronary sinus and great cardiac vein were segmented to simulate a guide wire, and its relation to the annular plane was assessed. Employed angulations and coplanarity of device depiction were investigated in 4 patients who underwent TMVI. Results: The mitral annulus is oriented in an anterior superior fashion with tilting to the right. SL and TT views were found at 29.4 ± 9.0° right anterior oblique (RAO), 20.1 ± 8.7° cranial (CAU) and 81.6 ± 18.9° RAO, 56.7 ± 8.0° caudal (CAU). The optimal projection curve and the relationship of coronary sinus to the mitral annular plane showed a wide intersubject variability. Commonly, the coronary sinus passed along the atrial wall with a mean distance of 13.2 ± 3.7mm toward the mitral annular plane at P2 and 1.4 ± 3.1mm anteriorly in alignment with the TT line. Coplanar depiction of the TMVI prosthesis was achieved in all 4 patients, with a compromise view chosen on the optimal projection curve between the TT view and SL view. Conclusion: CT allows for prediction of optimal fluoroscopic angulations to achieve a coplanar view of the mitral annulus. The relationship of the coronary sinus to the mitral annulus is variable and preprocedural CT segmentation may allow for a more patient-specific approach to the use of a coronary sinus guide wire as a fluoroscopic landmark.