Mitral Valve Repair of Atrial Functional Mitral Regurgitation in Heart Failure with Preserved Ejection Fraction

Mitral regurgitation in atrial fibrillation: Is a simple repair enough to tackle a complex problem?

BACKGROUND

Clinical and echocardiographic results of valve repair for mitral regurgitation in the setting of atrial fibrillation are poorly studied.

METHODS

Between January 2008 and December 2020, 89 patients underwent valve repair for mitral regurgitation in the setting of atrial fibrillation. Clinical and echocardiographic follow-up data were collected and studied. The primary composite endpoint consisted of all-cause mortality or hospitalization for heart failure.

RESULTS

Valve repair with true-sized annuloplasty was performed in 83 (93 %) and restrictive annuloplasty in 6 (7 %) patients. Early mortality occurred in 3 (3 %) and residual mitral regurgitation in 1 (1 %) patient. During a median follow-up of 5.4 years (interquartile range 3.4-9.5), 25 patients died, 6 due to end-stage heart failure. Ten patients were hospitalized for heart failure. The estimated event-free survival rate at 10 years was 48.2 % (95 % CI 33.5 %-62.9 %). Recurrent mitral regurgitation was observed in 14 patients and most often caused by leaflet tethering. When analyzed as a time-dependent variable, recurrent regurgitation was related to the occurrence of the primary endpoint (hazard ratio 3.192, 95 % CI 1.219-8.359, p = 0.018). On exploratory sub-analyses, no recurrent regurgitation was observed after restrictive annuloplasty or in patients with paroxysmal atrial fibrillation. Moreover, recurrent regurgitation was observed more often when signs of left ventricular impairment were present preoperatively.

CONCLUSIONS

Despite good initial results, recurrent regurgitation was a frequent observation after valve repair for mitral regurgitation in atrial fibrillation and had an effect on heart failure related morbidity and mortality. Refinements in the timing of surgery and surgical technique might help improve outcomes.

Functional Mitral Regurgitation and Heart Failure With Preserved Ejection Fraction: Clinical Implications and Management

Heart failure with preserved ejection fraction (HFpEF) is highly prevalent and associated with worse cardiovascular outcomes. The pathophysiology of HFpEF mostly relies on the development of elevated left ventricle filling pressure, diastolic dysfunction, and atrial dilatation and impairment. This dynamic process may eventually lead to the development of functional mitral regurgitation (MR), characterized by mitral annular dilatation and consequent leaflet remodeling, in the context of preserved left ventricular ejection fraction. These observations highlight the possible common pathophysiology of MR and HFpEF. However, less is known about the prevalence and the clinical value of MR in the context of HFpEF. This review aims to provide an overview of the association and interplay between functional MR and HFpEF, discuss the underlying mechanisms that are common to these diseases, and summarize potential targeted pharmacological treatments.

Assessing emerging causes of mitral regurgitation: atrial functional mitral regurgitation

Functional or secondary mitral regurgitation is linked to increased cardiovascular morbidity and mortality. From a mechanical perspective, secondary mitral regurgitation occurs due to an imbalance between the forces that tether the mitral leaflets and those that close them. This results in incomplete coaptation. Most commonly, functional mitral regurgitation, which occurs in both ischaemic and non-ischaemic disease states, is usually caused by dysfunction and changes in the left ventricle. Atrial functional mitral regurgitation (AFMR) is a disease state that has been more recently recognized. It occurs when mitral annular enlargement is associated with left atrial dilatation, preserving left ventricular geometry and function. AFMR is typically seen in patients with chronic atrial fibrillation or heart failure who have a conserved ejection fraction. Published reports and ongoing investigations vary in how they define AFMR. This publication examines the pathophysiology of AFMR and highlights the importance of having a common working standard for the definition of AFMR to ensure consistency in the data reported and to drive forward the much needed research into the outcomes and treatment strategies in this area. Several studies have reported that restrictive annuloplasty and transcatheter edge-to-edge repair can reduce mitral regurgitation and improve symptoms. This narrative review will explore the pathophysiology, echocardiographic diagnosis and treatment of AFMR.

Impact of concomitant mitral valve surgery on the clinical outcomes of patients with moderate functional mitral regurgitation and HFpEF undergoing aortic valve replacement: a cohort study

BACKGROUND

Functional mitral regurgitation (FMR) worsens the prognosis of patients with heart failure with preserved ejection fraction (HFpEF). While concomitant mitral valve surgery (MVS) is recommended for severe FMR during aortic valve replacement (AVR), the optimal treatment of moderate FMR, especially in those with HFpEF, remains unclear. This study aimed to evaluate the effect of MVS in patients with moderate FMR and HFpEF undergoing AVR.

METHODS

A total of 212 consecutive patients (AVR: 34.0%, AVR-MVS: 66.0%) during 2010 and 2019 were enrolled. Survival outcomes were compared. Inverse probability treatment weighting (IPTW) was used to balance the baseline characteristics. Kaplan-Meier curve and log-rank test were applied to compare the survival outcomes. The primary endpoint was the overall mortality.

RESULTS

The mean age was 58.9 [Formula: see text] 11.9 years, and 27.8% of them were female. During a median follow-up of 16.4 months, AVR-MVS did not reduce the risk of mid-term MACCE (hazard ratio [HR]: 1.53, 95% confidence interval [CI]: 0.57-4.17, P_log-rank = 0.396), while it showed a tendency toward higher MACCE risk in the IPTW analysis (HR: 2.62, 95% CI: 0.84-8.16, P_log-rank = 0.096). In addition, AVR-MVS increased the risk of mortality as compared to isolated AVR (0 vs. 10%, P_log-rank = 0.016), which was sustained in the IPTW analysis  (0 vs. 9.9%, P_log-rank<0.001).

CONCLUSION

In patients with moderate FMR and HFpEF, isolated AVR might be more reasonable than AVR-MVS.

Atrial functional mitral regurgitation: prevalence, characteristics and outcomes from the National Echo Database of Australia

AIMS

Atrial functional mitral regurgitation (AFMR) is characterised by left atrial and consequent mitral annular dilatation causing mitral regurgitation. AFMR is likely to become more common with population ageing, alongside increases in atrial fibrillation and heart failure with preserved ejection fraction; conditions causing atrial dilatation. Here, we aim to define the prevalence and characterise the patient and survival characteristics of AFMR in the National Echocardiographic Database of Australia (NEDA).

METHODS AND RESULTS

14 004 adults with moderate or severe FMR were identified from NEDA. AFMR or ventricular FMR (VFMR) was classified by LA size, LV size and LVEF. AFMR was found in 40% (n=5562) and VFMR in 60% (n=8442). Compared with VFMR, the AFMR subgroup were significantly older (mean age 78±11 years), with a higher proportion of females and of AF. Participants were followed up for a median of 65 months (IQR 36-116 months). After adjustment for age, sex, AF, and pulmonary hypertension, the prognosis for VFMR was significantly worse than for AFMR (HR 1.57, 95% CI 1.47 to 1.68 for all-cause and 1.73, 95% CI 1.60 to 1.88, p<0.001 for both). After further adjustment for LVEF, mortality rates were similar in VFMR and AFMR patients (HR 0.93, p=NS), though advancing age and pulmonary hypertension remained independently associated with prognosis.

CONCLUSIONS

AFMR is a common cause of significant functional MR that predominantly affects elderly female patients with AF. Advancing age and pulmonary hypertension independently associated with survival in FMR. Prognosis was better in AFMR compared with VFMR; however, this difference was accounted for by LV systolic impairment and not by MR severity.

Pathophysiology, Echocardiographic Diagnosis, and Treatment of Atrial Functional Mitral Regurgitation: JACC State-of-the-Art Review

The conventional view holds that functional mitral regurgitation (MR) is caused by restriction of leaflet motion resulting from displacement of the papillary muscle-bearing segments of the left ventricle. In the past decade, evidence has accrued suggesting functional MR can also be caused by left atrial enlargement. This underrecognized cause of secondary MR-atrial functional MR (AF-MR)-is mechanistically linked to annular enlargement, perturbations of annular contraction, and atriogenic leaflet tethering. AF-MR has been described in patients with atrial fibrillation and heart failure with preserved ejection fraction. Preliminary data suggest rhythm control may decrease MR severity in patients with atrial fibrillation. Additionally, several studies have reported reductions in MR and symptomatic improvement with restrictive annuloplasty and transcatheter edge-to-edge repair. This review discusses the pathophysiology, echocardiographic diagnosis, and treatment of AF-MR. AF-tricuspid regurgitation is also discussed.

Patch augmentation vs. valve replacement for patients with atrial functional mitral regurgitation and long-standing atrial fibrillation

BACKGROUND

Long-standing atrial fibrillation is associated with atrial functional mitral regurgitation (AFMR) with atriogenic tethering. We compared the outcomes of patch augmentation (PA) and valve replacement (VR) for AFMR.

METHODS

We retrospectively compared the data of 16 patients who underwent PA for AFMR with the data of 15 patients who underwent VR between 2008 and 2021. Patients with a left ventricular ejection fraction (LVEF) of <50% were excluded. We also performed atrial plication and left appendage closure if the patients had no weak atrial wall that led to severe bleeding.

RESULTS

The median age was 72.5 and 76.0 years in the PA and VR groups, respectively. The PA group had a longer cardiopulmonary bypass time (206 vs. 172 min, P=0.012). Although there were no differences in hospital morbidity and mortality between the PA and VR groups, one patient underwent reoperation for patch perforation in the PA group. The overall 3-year survival rate was 93.8% and 100% in the PA and VR groups, respectively (P=0.878). The 3-year rate of freedom from major adverse cardiac events was 75.0% and 53.6% in the PA and VR groups, respectively (P=0.181). Three and six patients were readmitted for congestive heart failure in the PA and VR groups, respectively. Two patients in the PA group developed severe recurrent regurgitation, including one patient who required reoperation. No patients in the VR group required reoperation. The postoperative left atrial volume index (LAVI) was associated with thromboembolic events (P=0.016).

CONCLUSIONS

PA may achieve comparable outcomes to those of VR for AFMR. Operative procedures should be chosen based on each patient's background. Atrial reduction could be considered to prevent thromboembolic events.

Mitral valve surgery for atrial functional mitral regurgitation: predicting recurrent mitral regurgitation and mid-term outcome

Objectives

This study aimed to elucidate the mid-term outcomes and risk factors for recurrent mitral regurgitation after mitral valve (MV) surgery for atrial functional mitral regurgitation (AFMR).

Methods and results

We retrospectively analyzed data of 50 consecutive patients (median age 74 years; 29 men) who underwent mitral valve surgery for AFMR between January 2001 and January 2019. Mean atrial fibrillation duration was 12 years. During the follow-up period of 4.6 ± 4.4 years, 5 cardiac-related deaths were identified. Five- and 10-year freedom from cardiac-related death rate for all patients was 88.4% and 78.6%. In total, 42 patients underwent MV repair with mitral annuloplasty and 8 underwent MV replacement. Five- and 10-year freedom from cardiac-related death rate in patients who underwent MV repair was 93.1% and 82.7%, which was better than MV replacement (log rank p = 0.04). During the follow-up period, MR recurrence rate was 16.8% at 5 and 10 years for the patients who underwent MV repair. Univariate analysis showed that partial band annuloplasty and preoperative elevated left ventricular end-systolic volume index were risk factors for recurrent MR after MV repair. Multivariate analysis identified partial band annuloplasty as the independent predictor for recurrent MR during long-term follow-up after MV repair for AFMR.

Conclusion

Patients who underwent MV repair for AFMR could have an acceptable mid-term outcome. However, MVR might not improve the mid-term outcome in patients with AFMR. The use of partial bands for mitral annuloplasty would not be recommended in terms of recurrent MR mid-term.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11748-022-01793-8.

Variable definitions and treatment approaches for atrial functional mitral regurgitation: A scoping review of the literature

OBJECTIVES

Atrial functional mitral regurgitation (AFMR) is a subtype of functional mitral regurgitation due to longstanding atrial fibrillation (AF) or heart failure with preserved ejection fraction. The variation in AFMR' definition and the common mode of treatment described in the literature remain unknown.

METHODS

We performed a scoping review of studies that surgically treated AFMR to characterize the existing variability in the definition of AFMR, the type of operations performed for AFMR valvulopathy, and the treatment for the chronic AF. We searched Medline, EMBASE, Cochrane Library, Scopus, and Web of Science since their inceptions for studies of patients affected by AFMR and surgically treated for their valvulopathy.

RESULTS

Twelve studies (n = 494 patients) met eligibility criteria. All studies excluded patients with signs of left ventricular (LV) dysfunction, but the way additional parameters were used to define AFMR at a more granular level varied across studies: nine studies (75%) used the presence of AF to define their AFMR cohorts, with five (41.2%) requiring a history of AF of >1 year; additionally, the threshold values for the LV ejection fraction differed (45%-55%). Isolated mitral annuloplasty was performed in 96.2% of patients. Broad variability was detected in the proportion of patients undergoing the Cox-Maze procedure (range, 17.8%-79.5%), pulmonary vein isolation (0.0%-66.7%), and left atrial appendage ligation (0.0%-100.0%).

CONCLUSIONS

AFMR remains variably defined in surgical studies, making comparisons across studies difficult. Mitral annuloplasty was most commonly performed. The proportion of AFMR patients undergoing concomitant procedures for AF varied substantially.

Clinical and Hemodynamic Effects of Percutaneous Edge-to-Edge Mitral Valve Repair in Atrial Versus Ventricular Functional Mitral Regurgitation

The present study aims to assess the clinical and hemodynamic impact of percutaneous edge-to-edge mitral valve repair with MitraClip in patients with atrial functional mitral regurgitation (A-FMR) compared with ventricular functional mitral regurgitation (V-FMR). Mitral regurgitation (MR) grade, functional status (New York Heart Association class), and major adverse cardiac events (MACE; all-cause mortality or hospitalization for heart failure) were evaluated in 52 patients with A-FMR and in 307 patients with V-FMR. In 56 patients, hemodynamic assessment during exercise echocardiography was performed before and 6 months after intervention. MR reduction after MitraClip implantation was noninferior in A-FMR compared with V-FMR (MR grade ≤2 at 6 months in 94% vs 82%, respectively, p <0.001 for noninferiority) and was associated with improvement of functional status (New York Heart Association class ≤2 at 6 months in 90% vs 80%, respectively, p = 0.2). Hemodynamic assessment revealed that cardiac output at 6 months was higher in A-FMR at rest (5.1 ± 1.5 L/min vs 3.8 ± 1.5 L/min, p = 0.002) and during peak exercise (7.9 ± 2.4 L/min vs 6.1 ± 2.1 L/min, p = 0.02). In addition, the reduction in systolic pulmonary artery pressure at rest was more pronounced in A-FMR: Δ SPAP -13.1 ± 15.1 mm Hg versus -2.2 ± 13.3 mm Hg (p = 0.03). MACE rate at follow-up was significantly lower in A-FMR versus V-FMR, with an adjusted odds ratio of 0.46 (95% confidence interval 0.24 to 0.88), which was caused by a reduction in hospitalization for heart failure. In conclusion, percutaneous edge-to-edge mitral valve repair with MitraClip is at least as effective in A-FMR as in V-FMR in reducing MR. However, the hemodynamic improvement and reduction of MACE were significantly better in A-FMR.

Outcome and durability of mitral valve annuloplasty in atrial secondary mitral regurgitation

OBJECTIVES

Atrial secondary mitral regurgitation (ASMR) is a clinically distinct form of Carpentier type I mitral regurgitation (MR), rooted in excessive atrial and mitral annular dilation in the absence of left ventricular dysfunction. Mitral valve annuloplasty (MVA) is expected to provide a more durable solution for ASMR than for ventricular secondary MR (VSMR). Yet data on MR recurrence and outcome after MVA for ASMR are scarce. This study sought to investigate surgical outcomes and repair durability in patients with ASMR, as compared with a contemporary group of patients with VSMR.

METHODS

Clinical and echocardiographic data from consecutive patients who underwent MVA to treat ASMR or VSMR in an academic centre were retrospectively analysed. Patient characteristics, operative outcomes, time to recurrence of ≥moderate MR and all-cause mortality were compared between patients with ASMR versus VSMR.

RESULTS

Of the 216 patients analysed, 97 had ASMR opposed to 119 with VSMR and subvalvular leaflet tethering. Patients with ASMR were typically female (68.0% vs 33.6% in VSMR, p<0.001), with a history of atrial fibrillation (76.3% vs 33.6% in VSMR, p<0.001), paralleling a larger left atrial size (p<0.033). At a median follow-up of 3.3 (IQR 1.0-7.3) years, recurrence of ≥moderate MR was significantly lower in ASMR versus VSMR (7% vs 25% at 2 years, overall log-rank p=0.001), also when accounting for all-cause death as competing risk (subdistribution HR 0.50 in ASMR, 95% CI 0.29 to 0.88, p=0.016). Moreover, ASMR was associated with better overall survival compared with VSMR (adjusted HR 0.43 95% CI 0.22 to 0.82, p=0.011), independent from baseline European System for Cardiac Operative Risk Evaluation II surgical risk score.

CONCLUSION

Prognosis following MVA to treat ASMR is better, compared with VSMR as reflected by lower all-cause mortality and MR recurrence. Early distinction of secondary MR towards underlying ventricular versus atrial disease has important therapeutic implications.

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.