Distinct leaflet-annular remodeling pattern in severe atrial functional mitral regurgitation: a three-dimensional echocardiography study.

Abstract

Background: Atrial functional mitral regurgitation (AFMR) is best described with normal left ventricular size and function, structurally normal mitral leaflets and dilated left atrium. Unlike the ventricular functional phenotype, changes in the annular geometry more than the tethering forces are the main culprit for mitral regurgitation. The aim of this study is to illuminate the leaflet-annular remodeling in patients with mitral regurgitation and atrial fibrillation (AF) using three-dimensional transesophageal echocardiography (3D TOE).

Results: Consecutive fifty patients with AFMR underwent transthoracic echocardiography and 3D TOE: 25 patients with AF and non-mild MR and 25 patients with AF and mild MR were studied. A special mitral valve analysis software was used to accurately assess the three unique pillars for MR: annular size, leaflets' geometry and tenting parameters. Compared to the mild MR group, non-mild MR group had long-standing AF of more than 1 year and larger left atrial volumes (51.83 ± 12.07 ml/m² vs 33.68 ± 10.97 ml/m², p < 0.001). No significant differences were noted in respect of tenting height, area and volume (13.06 ± 2.57 mm vs 11.43 ± 2.89 mm, p = 0.064, 3.58 ± 1.26 cm² vs 2.80 ± 0.95 cm², 0.081 and 6.70 ± 2.96 cm³ vs 5.04 ± 2.32 cm³, p = 0.081). Conversely, the non-mild MR group had larger annular area and perimeter (16.20 ± 3.90 cm² vs 13.51 ± 3.85 cm², p = 0.023 and 14.73 ± 1.72 cm vs 13.46 ± 1.79 cm, p = 0.033). Similarly, the non-mild MR group had larger anterior and posterior leaflets' areas (10.18 ± 4.02 cm² vs 8.71 ± 3.08 cm², p = 0.04 and 8.96 ± 2.60 cm² vs 7.30 ± 2.17 cm², p = 0.029). Correspondingly, more disproportionate leaflet-annular remodeling, as assessed by the ratio of total leaflets' area to the annular area, was noted in the non-mild MR as opposed to the mild MR group (1.22 ± 0.04 vs 1.26 ± 0.04, p = 0.008).

Conclusions: Recently, AFMR has been recognized as a remarkable entity of secondary MR with unique mechanisms. Annular dilatation with disproportionate leaflet remodeling can validate the central regurgitation. However, the call for more parameters is being emphasized to characterize the suitable candidates for percutaneous interventions.