Christopher Orton, DVM, PhD, DACVS
Brianna Potter, DVM, MS, DACVIM (Cardiology)
Current case selection guidelines for transcatheter edge-to-edge mitral valve repair (TEER) are based on ongoing experience with the early clinical trial in dogs, as well as current ACC/AHA guidelines for mitral valve interventions in humans (1). Dogs undergoing consideration for TEER should meet integrative criteria for severe mitral regurgitation (MR) independent of diuretic status. In addition, dogs should have functional mitral anatomy appropriate for an edge-to-edge repair.
Mitral Regurgitation Severity
Dogs undergoing TEER intervention should met ACC/AHA and ASE guidelines for severe MR in humans (1, 2). This could include dogs in ACVIM stage B2 or stage C. Dogs in late-stage C/D or atrial fibrillation are considered poor candidates for this procedure. Determination of MR severity should be based on consideration of multiple criteria. Criteria that support severe MR include:
Color-flow Doppler patterns should be assessed on multiple systolic images at appropriate gain and Nyquist settings. Single images can overestimate MR severity. Measurement of mitral regurgitant fraction (RF) by PISA, Simpson’s volumetric, and/or Doppler methods provides quantitative assessment of MR severity, and therefore represents an important objective criterion. Measurement of RF by multiple methods increases confidence in the assessment. Vena contracta (VC) width, regurgitant volume, and effective regurgitant orifice (ERO) area can also be considered but are dependent on patient size and limits for severity have not been fully established in dogs. Left ventricular and left atrial dilation (LVIDdN > 1.9, LA:Ao > 2.0) can be considered, but these are secondary changes in response to MR and are dependent on other influences such as chronicity and therapy. Indices of left ventricular systolic function can be considered as systolic dysfunction (e.g., LVEF < 60%, nLVIDs > 1.0) can be a negative predictor of outcome.
Mitral Functional Anatomy
Mitral functional anatomy is an important predictor of outcome in dogs undergoing TEER intervention. Guidelines for optimal functional anatomy are not absolute but represent a continuum from favorable to less favorable to unfavorable. Dogs with favorable functional anatomy can be expected to have the best outcomes in terms of reduction in MR severity and extension of life expectancy with low procedural risk. Dogs will less favorable functional anatomy may derive equivocal benefit from TEER
with some associated increase in procedural risk. Dogs with unfavorable functional anatomy carry a high procedural risk compared to potential benefits and are not candidates for the TEER procedure.
Criteria for mitral functional anatomy are:
1. Otto CM, Nishimura RA, Bonow RO, Carabello BA, Erwin JP, Gentile F, et al. 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease. Cirulation. 2021;143:e72-e227.
2. Zoghbi WA, Adams D, Bonow RO, Enriquez-Sarano M, Foster E, Grayburn PA, et al. Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation: A Report from the American Society of Echocardiography Developed in Collaboration with the Society for Cardiovascular Magnetic Resonance. J Am Soc Echocardiography. 2017;30:303-71.
