Impaired mitral annulus dynamics are responsible for Atrial functional MR finds JACC study.

Atrial functional mitral regurgitation (AFMR) is a relatively new entity that describes mitral regurgitation (MR) in the setting of normal left ventricular function, structurally normal leaflets, and mitral annular dilation, which is encountered in patients with atrial fibrillation and/or heart failure with preserved ejection fraction (HFpEF). The mechanisms underlying this entity are still poorly described although a role of annular dilatation has been suggested.

In the latest issue of JACC Cardiovascular Imaging, Deferm et al provide evidence that annular dynamics play a crucial role in the pathophysiology of AFMR besides annular dilation. Authors found that AF related blunted presystolic narrowing contributes to AFMR and sinus rhythm restoration allows gradual recovery of presystolic annular dynamics.

Fifty-three patients with persistent AF and normal left ventricular ejection fraction were prospectively examined by echocardiography before, immediately after, and 6 weeks after electric cardioversion to sinus rhythm. Annular motion was assessed during AF and in sinus rhythm with the use of 3-dimensional analysis software, and the relationship with MR severity was explored.

Comprehensive 3-dimensional transesophageal echocardiographic evaluation before and 6 weeks after sinus reconversion, revealed an increase in annular dynamics, which was paralleled by a decrease in AFMR.

At baseline, the mitral annulus appeared adynamic, while restoring sinus rhythm resulted in near normal annular size variation during the cardiac cycle, which was mainly caused by the return of a presystolic (atrial) contraction.

The effective regurgitant orifice area (EROA) decreased from 0.15 cm 2 during AF to 0.09 cm 2 at follow-up in the total cohort, and from 0.27 to 0.16 in the subgroup with effective regurgitant orifice area (EROA) ≥0.20 cm 2 . The change in presystolic annular motion was the only independent determinant of the decrease in MR severity by optimizing annular-leaflet imbalance.

Authors also suggest that the balance between the total mitral leaflet area and the minimal closed leaflet area needed during systole is a key determinant for the occurrence of AFMR in patients with persistent AF.

The present study provides unique insights into mitral annular dynamics in AF and the mechanisms underlying AFMR. It is demonstrated that blunting of the presystolic (atrial) annular narrowing is the predominant difference in annular dynamics between AF and sinus rhythm, significantly affecting mitral valve competence in AF.

Hence, for management of AFMR, AF therapy should ideally extend beyond anticoagulation and rate-control therapy, focusing on preserving sinus rhythm early in light of annular anatomical and mechanical remodeling.

The recently published EAST (Early Treatment of Atrial Fibrillation for Stroke Prevention trial) showed significantly better cardiovascular outcomes after early rhythm-control therapy in subjects with early AF and cardiovascular conditions, compared with usual care.

Whether this is partially attributable to a reduction in MR severity among nearly one-half of patients with concomitant valvular disease is unknown.

Source: JACC CI: J Am Coll Cardiol Img. 2022 Jan, 15 (1) 1–13