Clinical feasibility study of transcatheter edge-to-edge mitral valve repair in dogs with the canine V-Clamp device

Abstract

Objective: To determine procedural feasibility, safety, and short-term efficacy in dogs with severe degenerative mitral regurgitation (MR) undergoing transcatheter edge-to-edge repair (TEER) with a canine-specific device.

Design: Prospective, single-arm (uncontrolled), single-institution clinical feasibility study.

Animals: Fifty client-owned dogs with severe degenerative MR operated over a 28-month period.

Methods: TEER was performed using the canine mitral V-Clamp via a transapical approach using transesophageal echocardiographic and fluoroscopic guidance. Indices of MR severity were determined by echocardiography the day before and 2 to 3 days after the procedure.

Results: Procedural feasibility was 96% based on delivery of at least one device in 48 of 50 dogs. There were no procedural deaths. Procedural safety was 96% based on survival to hospital discharge in 48 of 50 dogs. Euthanasia in 2 dogs prior to hospital discharge was due to damage of the mitral valve and worsened MR after the procedure. Device-related adverse event rate was 6.3% based on 3 events (single-leaflet device detachment, locking failure, locking failure with device embolization) in 59 implanted devices. All three events were nonfatal and successfully treated with a second device. Median regurgitant volume (mL/kg) decreased (p < 0.001) from 2.3 [1.9, 3.1] to 1.1 [0.3, 1.8]. Median effective regurgitant orifice area (cm²/m²) decreased (p < 0.001) from 0.60 [0.40, 0.80] to 0.25 [0.10, 0.50].

Conclusion and clinical importance: Initial feasibility results support continued development of TEER as a procedurally feasible, relatively low-risk, and low morbidity treatment for degenerative MR in dogs. Operator experience and case selection are likely to be important components of success of this technique. Evidence of short-term efficacy is promising but needs to be verified with longer-term follow up.

Keywords: degenerative mitral valve disease; mitral regurgitation; myxomatous mitral valve disease; transapical intervention; transcatheter mitral valve repair.

Figure 1

Transesophageal echocardiographic en face images of the mitral valve before (A) and after (B) transcatheter edge-to-edge mitral valve repair (TEER). Wide prolapse of the A2 segment of the mitral valve is present before TEER. The TEER procedure results in a double orifice mitral valve with the clamp location positioned across the A2 and P2 segments (dashed arrowed line). Ao, aorta.

Figure 2

Transesophageal echocardiographic (TEE) and fluoroscopic imaging for transcatheter edge-to-edge mitral valve repair. Views for TEE include two-dimensional commissural and inflow-outflow views, and three-dimensional en face view of the mitral valve. The fluoroscopic view is a lateral projection of the dog in right lateral recumbency. The aorta (Ao) is oriented at 9 o’clock to provide synchronous cranial-caudal movement of the device between the TEE inflow-outflow, en face, and fluoroscopic views. L, lateral; M, medial; P, posterior.

Figure 3

Canine Mitral V-Clamp delivery system, transmitral mesh guide, and V-Clamp. The V-Clamp has 3 positions: open, closed, and locked.

Figure 4

Study profile for the feasibility clinical study of transcatheter edge-to-edge mitral valve repair in dogs with the canine mitral V-Clamp device.

Figure 5

Distribution of regurgitant volume (mL/kg) and regurgitant fraction (%) severity before and at hospital discharge after transcatheter edge-to-edge mitral valve repair.

Figure 6

Distribution of regurgitant fraction (%) severity before and at hospital discharge after transcatheter edge-to-edge mitral valve repair for the first and second half of cases performed.