Percutaneous increase of mitral leaflet coaptation length after mitral valve repair: results from a preclinical study.

Objectives: The failure of mitral repairs can be the result of inadequate leaflet coaptation length (CL< 8 mm at the A2-P2 level). A new annuloplasty ring conceived by the authors enables post-surgical CL increase using percutaneous balloon catheter technology. We conducted preclinical studies to assess the in vivo feasibility of the procedure and the safety of the postimplant deformable mitral ring.
Methods: The new annuloplasty ring allows the percutaneous and progressive displacement of each of the 3 anatomical regions of the posterior mitral annulus towards the anterior. Displacement is permanent and induced by an angioplasty balloon catheter inserted in a line connecting the ring to the subcutaneous tissue. Under general anaesthesia and cardiopulmonary bypass, healthy adult sheep had mitral annuloplasty. The device was implanted using the interrupted suture technique. The connection line exited the left atrium and reached the skin. Epicardial echocardiography allowed assessment of valve competence, leaflet CL, the mitral valve area and the mitral valve gradient. The mandrel was removed, and the dedicated catheter balloon was inserted into the connection line. The balloon was inflated in the P2 position under fluoroscopic control, and epicardial echocardiography was used to assess the functional parameters of the valve. One month later, the balloon was inserted again through the connection line; the P1 and P3 areas were deformed to increase CL. Valve parameters were measured again using transthoracic echocardiography. After 6 months, transthoracic echocardiography was used to assess the functional parameters of the valve. The sheep were sacrificed and autopsied.
Results: Ten adult sheep survived the procedure. A 30-mm ring was implanted in all the sheep, and the 6-month follow-up was uneventful for all of them. The CL increased by 100% (4.2 ± 2 mm-8.5 ± 2 mm, P < 0.001); the transmitral gradient increased from 2 ± 0.5 mmHg to 4 ± 0.5 mmHg (P < 0.001) and the effective orifice area decreased from 4.5 ± 0.6 cm2 to 3.5 ± 0.6 cm2 (30% reduction, P < 0.001).
Conclusions: The device safely enabled a significant improvement of leaflet CL after mitral annuloplasty with an angioplasty-like technique, and the improvement was stable over time. The reshaping of the mitral annulus provided by this technology should benefit all patients having mitral repairs. The future of mitral regurgitation treatment is towards surgical correction followed by late, iterative, percutaneous adjustments of mitral leaflets coaptation.