Philipp Blanke MD, Presenter: Nothing to Disclose

Bruce Precious MD, Abstract Co-Author: Nothing to Disclose

Shalan Alaamri, Abstract Co-Author: Nothing to Disclose

Cameron John Hague MD, Abstract Co-Author: Nothing to Disclose

Darra Thomas Murphy MD, FRCPC, Abstract Co-Author: Nothing to Disclose

Jonathon Avrom Leipsic MD, Abstract Co-Author: Speakers Bureau, General Electric Company Speakers Bureau, Edwards Lifesciences Corporation Consultant, Heartflow, Inc Consultant, Circle Cardiovascular Imaging Inc

Adam Berger, Abstract Co-Author: Nothing to Disclose

John Webb MD, FRCPC, Abstract Co-Author: Consultant, Edwards Lifesciences Corporation

To define the methodology for computed tomography (CT)-based functional “D –shaped” mitral annular assessment for transcatheter mitral valve implantation (TMVI) and compare these novel measurements to traditional “saddle-shaped” mitral annular assessment.

ECG-gated, end-diastolic CT data sets of 28 patients (mean age 72.7±10.2 years) with severe functional mitral valve regurgitation undergoing diagnostic work-up for potential minimal-invasive mitral intervention were analyzed. The annular contour was manually segmented and fibrous trigones were identified yielding annular perimeter, projected area, trigone-to-trigone (TT) distance, septal-lateral (SL) distance and annular height. The traditional saddle shaped annulus was defined including the aortomitral continuity. The functional D-shaped annulus was defined as being limited anteriorly by the TT line, excluding the aortomitral continuity. Hypothetical left ventricular outflow tract (LVOT) clearance and orthogonal projection angles were calculated. 

Projected area, perimeter and SL distance were found to be significantly smaller for the functional, D-shaped annulus than for the saddle-shaped annulus (11.2±2.7mm2 vs. 13.0±3.0cm2, 122.5±13.0mm vs. 136.0±15.5mm, 32.1±4.0mm vs. 40.1±4.9mm respectively, p<0.001). TT distances were identical (32.7±4.1mm). The D-shaped annulus was more planar demonstrating a reduced annular height (2.4±1.0mm vs. 10.6±1.8mm, p<0.001). Hypothetical LVOT clearance was significantly reduced for the saddle-shaped annulus, but preserved for the D-shaped annulus (10.7±2.2mm vs. 17.5±3.0mm, p<0.001). A line of perpendicularity for orthogonal views was identified. SL views were on average found at 25.5±7.7° RAO, 22.5±10.2° cranial, whereas TT views were found at 74.7±20.5° RAO, 57.0±8.4° caudal.  

The historically established methodology for sizing a saddle-shaped mitral annulus appears inappropriate for TMVI, yielding significantly larger dimensions and reduced LVOT clearance compared to the functional, D-shaped annulus approach. CT-based annular assessment may aid pre-procedural sizing, ensuring appropriate patient and device selection and the derivation of appropriate co-axial angles of deployment.

CT-based mitral annular assessment may aid pre-procedural sizing, ensuring appropriate patient and device selection and the derivation of appropriate co-axial angles of deployment in th context of TMVI.

Blanke, P, Precious, B, Alaamri, S, Hague, C, Murphy, D, Leipsic, J, Berger, A, Webb, J, Mitral Annular Evaluation with Computed Tomography in the Context of Transcatheter Mitral Valve Implantation: A New Paradigm.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14018640.html