Etiology of Atrial Functional Mitral Regurgitation: Insights from Transthoracic Echocardiography in 159 Consecutive Patients with Atrial Fibrillation and Preserved Left Ventricular Ejection Fraction

A review of the impact, pathophysiology, and management of atrial fibrillation in patients with heart failure with preserved ejection fraction

Patients with heart failure with preserved ejection fraction (HFpEF) and atrial fibrillation (AF) have increased mortality and increased risk of stroke. Due to the heterogeneous nature of both disease processes, it is difficult to ascertain whether the diagnosis and progression of AF is the cause of deterioration or if it is a symptom of worsening heart failure. This presents physicians with a clinical conundrum of whether optimizing their heart failure will decrease the overall AF burden or if restoration of sinus rhythm is necessary to optimize patients with HFpEF. In this paper, we will review the impact of AF in patients with HFpEF, the pathophysiology and heterogeneity of HFpEF and AF, and the management of these patients. As HFpEF and AF become more prevalent, managing these disease processes needs standardization to improve outcomes. Further research is needed to understand the complex interplay between AF and HFpEF to help determine the best management strategy.

Aortomitral angle affects cardiovascular events after mitral valve repair for atrial functional mitral regurgitation

PURPOSE

This study aimed to elucidate the geometric parameters of the aortomitral (AM) complex affecting postoperative cardiovascular events (CVEs) in patients with atrial functional mitral regurgitation (MR).

METHODS

From October 2008 to August 2018, we performed mitral and tricuspid valve repairs in 58 patients with atrial functional MR. We examined the determinants of CVEs using preoperative and postoperative echocardiographic data. Furthermore, we analyzed the effect of left atrial (LA) plication on AM geometries after surgery. The follow-up period ranged from 56 to 3283 days (median, 1073 days).

RESULTS

All patients underwent mitral and tricuspid annuloplasty. Seventeen patients (29%) underwent additional LA plication. The AM angle was narrowed after surgery in patients with CVEs (115° ± 6.8° to 106° ± 4.2°, p = .00336), whereas it widened in patients without CVEs (115° ± 7.4° to 118° ± 8.4°, p = .0278). The postoperative AM angle was an independent predictor of postoperative CVEs (p = .000829). LA plication was not a predictor of CVEs; however, it was a predictor of the obtuse postoperative AM angle (p = .0071).

CONCLUSIONS

Our results suggest that a narrow postoperative AM angle is an independent predictor of postoperative CVEs. Additional LA plication reduces the sharpening of the AM angle, which may prevent CVEs after mitral valve repair for atrial functional MR.

Three-dimensional echocardiography for predicting mitral stenosis after MitraClip for functional mitral regurgitation

BACKGROUND

Postprocedural mitral stenosis (MS), or increased transmitral mean pressure gradient (TMPG), is one of the limitations of transcatheter edge-to-edge mitral valve repair using MitraClip (Abbott Vascular Inc., Santa Clara, USA); however, the usefulness of three-dimensional transesophageal echocardiography (3D-TEE) for predicting postprocedural MS in functional mitral regurgitation (MR) has not been fully elucidated.

METHODS

Eighty-two consecutive functional MR patients who underwent transcatheter mitral valve repair using MitraClip were retrospectively studied. Postprocedural MS was defined as TMPG ≥ 5 mmHg by echocardiography.

RESULTS

Ten patients had postprocedural MS, and 3D-TEE showed that patients with postprocedural MS had smaller preprocedural mitral valve orifice area (MVOA), anteroposterior and mediolateral diameter, leaflet area, and annulus area. Receiver operating characteristic analysis showed that leaflet area (area under the curve (AUC) 0.829), annulus area (AUC 0.813), anteroposterior diameter (AUC 0.797) and mediolateral diameter (AUC 0.803) evaluated using 3D-TEE were predictors of postprocedural MS, and their predictive abilities were higher than those of preprocedural MVOA (AUC 0.756) and preprocedural TMPG (AUC 0.716). Adding leaflet area to TMPG and MVOA resulted in higher C-statistics for predicting postprocedural MS (from 0.716 to 0.845 and from 0.756 to 0.853, respectively).

CONCLUSIONS

In functional MR patients treated with MitraClip, leaflet area and annulus area evaluated using 3D-TEE had high predictive values for postprocedural MS, and their predictive abilities were higher than those of preprocedural TMPG or MVOA.

Mechanism of improvement in atrial functional mitral regurgitation after catheter ablation for atrial fibrillation: Three-dimensional analysis using multislice computed tomography

BACKGROUND

Several factors associated with atrial functional mitral regurgitation development have been reported; however, geometric changes in the mitral apparatus after catheter ablation for atrial fibrillation have not been sufficiently investigated. This study aimed to clarify what determines improvements in atrial functional mitral regurgitation after sinus rhythm restoration in patients who underwent catheter ablation for atrial fibrillation by using multislice computed tomography.

METHODS

We analysed volumetric multislice computed tomography images of 44 atrial fibrillation patients with significant atrial functional mitral regurgitation (moderate or worse) before and after catheter ablation. We measured the three-dimensional geometry of the mitral apparatus including the mitral annular area and interpapillary muscle distance. We calculated the differences before and after catheter ablation (Δmitral annular area, Δinterpapillary muscle distance) and assessed mitral regurgitation severity based on the mitral regurgitant jet area and its changes before and after catheter ablation (Δjet area) using transthoracic echocardiography.

RESULTS

After catheter ablation, the jet area was significantly decreased. The left ventricular ejection fraction was significantly increased and the left ventricular volume had a decreasing trend. The Δjet area was significantly correlated with the Δinterpapillary muscle distance (r = .43; p = .004). The Δinterpapillary muscle distance was the strongest determinant of improvements in atrial functional mitral regurgitation severity (p = .026).

CONCLUSIONS

Decreased interpapillary muscle distance was strongly associated with improvements in atrial functional mitral regurgitation. Amelioration of left ventricular dysfunction by sinus rhythm restoration might be related to improvements in atrial functional mitral regurgitation after catheter ablation.

Surgical considerations for atrial functional regurgitation of the mitral and tricuspid valves based on the etiological mechanism

Atrial functional mitral regurgitation is a hot research topic in the field of mitral valve disease. Atrial functional mitral regurgitation is distinctly different from ventricular functional mitral regurgitation. The surgical indications for atrial functional mitral regurgitation have not been well established because of the small amount of evidence gathered to date. Mitral annular plication with an artificial ring is an essential surgical procedure because dilatation of the mitral valve annulus is a main factor underlying this pathology. Most of these cases can be treated by mitral annuloplasty alone. However, additional procedures, such as application of artificial chordae to the anterior leaflet for pseudo-prolapse, and posterior leaflet augmentation with a pericardial patch, are required in advanced cases with a giant left atrium and extremely enlarged mitral annulus. Chronic atrial fibrillation causes enlargement of the right and left atria. This pathology is a bilateral atrioventricular valve disease (dual-valve disease). Therefore, the conventional guidelines of single-valve disease should not be applied. Although atrial functional tricuspid regurgitation is underappreciated, tricuspid annuloplasty should be considered for most patients to prevent future regurgitation. In addition to the mitral and tricuspid valve procedure, integrated surgical management, including plication of the atrium and left appendage closure, is required. This review summarizes the current considerations of surgical treatment for atrial functional regurgitation of the mitral and tricuspid valves based on the etiological mechanism.

Looking into the Mechanistic Link Between Mitral Regurgitation and Atrial Fibrillation

Atrial functional mitral regurgitation (AFMR) can occur in patients with atrial fibrillation despite a preserved left ventricular systolic function. AFMR has received attention as a cause of heart failure; it is a therapeutic target in patients with heart failure with atrial fibrillation. Mitral annular dilatation from atrial fibrillation-induced left atrial dilatation is necessary for the generation of AFMR. Posterior mitral leaflet hamstringing also relates to the generation of AFMR. Further mitral annular dilatation owing to progressive left atrial and left ventricular dilatations, with mitral regurgitation-induced volume overload, worsens AFMR.

Prognostic comparison of atrial and ventricular functional mitral regurgitation

Objective

Atrial functional mitral regurgitation (A-FMR) has been suggested as a new aetiology of functional MR (MR); however, its prognosis and prognostic predictors are not fully elucidated. Aim of this study was to investigate the prognosis and prognostic predictors of A-FMR in comparison with ventricular functional MR (V-FMR).

Methods

Three hundred and seventy-eight consecutive patients with moderate-to-severe or severe functional MR were studied. Functional MR was classified into V-FMR (N=288) and A-FMR (N=90) depending on the alterations of left ventricle (LV) or left atrium (LA) along with clinical context and diagnosis of ischaemic heart disease or cardiomyopathy.

Results

During a median follow-up of 4.1 (2.0–6.7) years, all-cause mortality, cardiovascular mortality and heart failure (HF) hospitalisation occurred in 98 (26%), 81 (21%) and 177 (47%) patients, respectively, and rates of these events and the composite end point of all-cause mortality and HF hospitalisation were consistently higher in V-FMR than A-FMR (unadjusted HR 1.762 (95% CI 1.250 to 2.438), p<0.001; adjusted HR 1.654 (95% CI 1.027 to 2.664), p=0.038, for the composite end point). Further analysis showed different prognostic predictors between V-FMR and A-FMR; while age and LA volume index were independent prognostic predictors of both V-FMR and A-FMR, systolic blood pressure and B-type natriuretic peptide were also those of V-FMR, and estimated glomerular filtration rate, LV end-systolic dimension and tricuspid regurgitation were also those of A-FMR.

Conclusions

The prognosis of V-FMR was significantly worse than that of A-FMR, and prognostic predictors were different between V-FMR and A-FMR. Our study suggests the importance of discriminating A-FMR and V-FMR, and that different treatment strategies may be considered for each aetiology.

A new disease entity: Atrial functional mitral regurgitation

Functional mitral regurgitation (MR) has been traditionally known as secondary MR resulting from left ventricular (LV) dilatation and systolic dysfunction. However, deterioration of functional MR also relates to mitral annular (MA) dilatation. Furthermore, MA dilatation due to left atrial dilatation in patients with atrial fibrillation (AF) can also cause functional MR, even in the absence of LV systolic dysfunction, in a condition referred to as "atrial functional MR" (AFMR). AFMR also has other etiological factors, including disruption of the MA saddle shape, reduction in MA contractility, inadequate compensation for the MA dilatation resulting from the lack of leaflet remodeling, and hamstringing of the posterior mitral leaflet by atriogenic tethering. AFMR has recently received much attention as an important cause of heart failure, and it represents a considerable therapeutic target in heart failure patients with AF. The traditional functional MR occurring in patients with LV dilatation and systolic dysfunction has since been designated "ventricular functional MR" (VFMR) to distinguish it from AFMR. This review article compares the current perceptions of newly recognized AFMR with those of traditional VFMR.