Biological versus prosthetic ring in mitral-valve repair: enhancement of mitral annulus dynamics and left-ventricular function with pericardial annuloplasty at long term.

OBJECTIVE: The effects of different annuloplasty rings on mitral annulus dynamics and left-ventricular (LV) function after mitral-valve repair (MVR) are still controversial. This study sought to compare biological versus prosthetic rigid rings for annular remodelling in MVR at long term.
METHODS: Forty-four consecutive patients were retrospectively enrolled. All patients had isolated posterior-leaflet prolapse and underwent identical surgical mitral-valve reconstruction (quadrangular resection of the posterior leaflet associated with annuloplasty). Twenty-three patients underwent mitral annuloplasty with an autologous pericardial ring (group I), whereas 21 patients had MVR with a Carpentier-Edwards rigid ring (group II). No differences existed between the groups in terms of pre-operative patient profile. Post-operative LV systolic indices have been assessed by two-dimensional echocardiography at rest and during supine bicycle exercise. Mitral annular motion has been examined by means of the extent of mitral annulus systolic excursion (MASE), as measured in four longitudinal LV segments (anterior, inferior, septal and lateral). Mean and peak trans-mitral flow velocities (TMFV) have been also evaluated by continuous-wave Doppler.
RESULTS: The mean follow-up did not differ between the groups, those being 41+/-12 months in group I (range17-65 months) and 46+/-15 months in group II (range 23-83 months), respectively. Post-operative echocardiographic study did not show significant mitral regurgitation at rest or at peak exercise in any patient. ANOVA analysis for repeated measures showed a significant interaction in peak TMFV (F((1,42))=5.23; P=0.03), and in left-ventricular ejection fraction (LVEF; F((1,42))=7.61, P=0.01). The analysis of contrasts showed a significant increase in TMFV in both groups (group I from 1.22+/-0.22 to 1.79+/-0.32 m/s, t=-8.8, P<0.0001; and group II from 1.19+/-0.17 to 1.96+/-0.33 m/s, t=-12.8, P<0.0001). Recruitment of LVEF reserve during exercise was observed only in group I (from 59.5+/-6 to 65.8+/-6%, t=-3.95, P<0.005), whereas no substantial change occurred in LV performance in group II. A trend towards better MASE at all the studied longitudinal segments at rest and during exercise was observed in group I. No minor or major calcifications have been observed on pericardial rings.
CONCLUSIONS: The autologous pericardium seems to be superior to rigid prosthetic rings for annuloplasty in MVR since it provides more favourable mitral annulus dynamics and preserves LV function during stress conditions. Effective and durable annular remodelling with the autologous pericardium is achieved up to 6 years from surgery, with no echocardiographic sign of degeneration in the long term. Further studies are required to compare biological versus flexible prosthetic rings in MVR.