Abstract 15797: Fibrotic Remodeling and Stiffening of Mitral Valve Leaflets After Undersizing Ring Annuloplasty to Correct Ischemic Mitral Regurgitation
Introduction: Systolic leaflet coaptation after undersizing ring annuloplasty (URA) to repair ischemic mitral regurgitation (IMR) is highly non-physiological, with a hyper-extending anterior leaflet and restricted posterior leaflet. Such a leaflet configuration elevates leaflet stresses and could trigger pathological leaflet remodeling.
Hypothesis: Abnormal leaflet stresses after URA can trigger fibrotic leaflet remodeling(Fig 1A). Adding a sub-valvular repair, such as papillary muscle approximation (PMA), that restores physiological coaptation and leaflet kinematics may inhibit this process.
Methods: Eighteen swine with chronic IMR were randomized to four groups: (G1, n=3) sham/control; (G2, n=3) URA; (G3, n=6) URA+PMA; and (G4, n=6) PMA only. At 3 months post-repair, cardiac MRI was performed to assess leaflet kinematics, and valve leaflets were explanted and analyzed for fibrotic remodeling with immunoblotting.
Results: Anterior leaflet hyper-extension was consistently observed in all the repair groups, however its tenting was reduced (Fig 1B). Posterior leaflet restriction was evident in URA, which improved with URA+PMA and PMA (Fig 1B). Heat shock protein 47 (HSP47), a chaperone of collagen biosynthesis was elevated in both the leaflets after URA, but was less in URA+PMA and PMA (Fig 1C). Lysyl oxidase (LOX), a collagen crosslinking protein was reduced in PMA compared to URA, but such changes were not observed in the posterior leaflet. Pro-collagen 1 propeptide (PICP) was significantly elevated in the anterior and posterior leaflets after URA, and reduced in UMA+PMA or PMA only.
Conclusions: Anterior and posterior leaflet fibrosis is clearly evident at 3 months after URA, and was inhibited by restoring physiological leaflet mobility and coaptation with a PMA. Sub-valvular repair in IMR could not only improve valvular competence but potentially inhibit adverse fibrotic leaflet remodeling and have an impact on repair durability.
Author Disclosures: A. Sielicka: None. E.L. Sarin: Consultant/Advisory Board; Modest; WL Gore. W. Shi: None. D. Espiritu: None. V.H. Thourani: Research Grant; Modest; Abbott Medical, Boston Scientific, Edwards Lifesciences, Medtronic. Consultant/Advisory Board; Modest; St Jude Medical, Edwards Lifesciences. R.A. Guyton: None. M. Padala: Research Grant; Modest; American Heart Association, Coulter Foundation, Georgia Research Alliance, Carlyle fraser Heart Center.
- © 2016 by American Heart Association, Inc.