Impact of Leaflet-to-Annulus Index on Residual Regurgitation in Dogs Undergoing Mitral Valve Transcatheter Edge-to-Edge Repair

Abstract: Background – Mitral valve transcatheter edge-to-edge repair (TEER) can reduce the severity of mitral regurgitation (MR) and improve prognosis for dogs with myxomatous mitral valve disease. Leaflet-to-annulus index (LAI), a measure of leaflet annular mismatch, may impact procedural success. Hypothesis/Objectives – We hypothesized that LAI will significantly impact 24-hour post-operative regurgitant fraction (RF) in dogs underdoing TEER. Animals - 43 client-owned dogs, (28-Stage C, 15-Stage B2), undergoing mitral valve TEER. Methods – Prospective observational study. The following variables were evaluated for their impact on procedural success: LAI, operator experience, commissural vena contracta width (VC%), device to annulus ratio, and anterior-posterior dimension (APdiam). 24-hour post-operative RF was quantified using transthoracic volumetric method. Normality was assessed and Mann-Whitney tests were used to compare groups. Outcome variables were assessed using linear regression. Results – Thirty-nine of 43 dogs (91%) survived and had a 24-hour post-operative echocardiogram. The median measurement for all dogs was: LAI = 1.0 (min 0.898, max 1.42), post-operative RF = 39% (min 12%, max 68%), VC% = 57% (min 33%, max 78%), AP dimension = 17.5mm (min 14mm, max 24mm), and device to annuls ratio = 0.91 (min 0.81, max 1.06). Median operator experience was 9 months (min 1 month, max 28 months). Multiple linear regression found LAI (P=0.015) and experience (P=0.012) to be independent predictors of post-operative RF. Dogs with RF < 40% (n=23) had significantly larger LAI (P=0.02) compared to dogs with RF >40% (n=16). Conclusions and Clinical Importance - LAI and operator experience significantly impact short-term procedural success.