Atrial functional mitral regurgitation

Atrial functional mitral regurgitation

Atrial functional mitral regurgitation (MR) has been featured as the JACC Review Topic of the Week [1]. Atrial functional MR is due to isolated mitral annular dilatation with insufficient leaflet growth and impaired annular dynamics. It occurs typically in atrial fibrillation and heart failure with preserved ejection fraction (HFpEF). It is different from MR secondary to left ventricular dysfunction. In left ventricular dysfunction, tethering of mitral leaflets is an important cause for mitral regurgitation while it is not so in atrial functional MR. Hence MR secondary to left ventricular dysfunction is usually an eccentric jet, whereas atrial functional MR produces a central jet as the leaflets fail to coapt in the centre. There is insufficient leaflet lengthening or remodeling to produce coaptation in the setting of annular dilatation [2].

Atrial functional MR can occur in 6-7% cases of lone atrial fibrillation. The prevalence is much higher in HFpEF (up to 53%). The severity of left atrial dilatation is much more in atrial functional MR when compared to MR secondary to left ventricular failure.

Guideline directed medical therapy is the cornerstone in the management of secondary (functional) mitral regurgitation. Targeting atrial fibrillation by catheter ablation might prevent progression of HFpEF and potentially atrial functional MR. Surgical restrictive mitral annuloplasty improves leaflet coaptation by reducing annular dimensions. But recurrence rate up to 32.6% has been reported 12 months after an initially successful mitral annuloplasty [3]. At the same time, a chordal sparing mitral valve replacement in the same study had only 2.3% recurrence rate. That study of 251 patients with severe ischemic mitral regurgitation showed that mitral valve replacement provided a more durable correction of mitral regurgitation. There was no significant difference in clinical outcome between repair and replacement in that study.

616 patients with secondary mitral regurgitation underwent the MitraClip procedure in EVEREST II (Endovascular Valve Edge-to-Edge Repair Study) [4]. Acceptable safety, reduction of severity of MR, symptomatic improvement and positive ventricular remodeling were documented in the study.

References

1. Deferm S, Bertrand PB, Verbrugge FH, Verhaert D, Rega F, Thomas JD, Vandervoort PM. Atrial Functional Mitral Regurgitation. J Am Coll Cardiol. 2019 May 21;73(19):2465-2476.
2. Delgado V, Bax JJ. Atrial Functional Mitral Regurgitation: From Mitral Annulus Dilatation to Insufficient Leaflet Remodeling. Circ Cardiovasc Imaging. 2017 Mar;10(3). pii: e006239.
3. Acker MA, Parides MK, Perrault LP, Moskowitz AJ, Gelijns AC, Voisine P, Smith PK, Hung JW, Blackstone EH, Puskas JD, Argenziano M, Gammie JS, Mack M, Ascheim DD, Bagiella E, Moquete EG, Ferguson TB, Horvath KA, Geller NL, Miller MA, Woo YJ, D’Alessandro DA, Ailawadi G, Dagenais F, Gardner TJ, O’Gara PT, Michler RE, Kron IL; CTSN. Mitral-valve repair versus replacement for severe ischemic mitral regurgitation. N Engl J Med. 2014 Jan 2;370(1):23-32.
4. Ailawadi G, Lim DS, Mack MJ, Trento A, Kar S, Grayburn PA, Glower DD, Wang A, Foster E, Qasim A, Weissman NJ, Ellis J, Crosson L, Fan F, Kron IL, Pearson PJ, Feldman T; EVEREST II Investigators. One-Year Outcomes After MitraClip for Functional Mitral Regurgitation. Circulation. 2019 Jan 2;139(1):37-47.