Functional Mitral Regurgitation: Imaging Insights, Clinical Outcomes and Surgical Principles

Outcomes of maze procedure and mitral valve surgery in atrial functional mitral regurgitation: a retrospective study

BACKGROUND

Atrial functional mitral regurgitation (AFMR) is a newly discovered condition associated with longstanding atrial fibrillation. This retrospective study aimed to analyze the outcomes of the maze procedure and mitral regurgitation (MR) surgery in AFMR and atrial fibrillation in comparison with those in degenerative MR (DMR).

METHODS

Patients who underwent mitral valve repair/replacement with a maze procedure at a hospital (July 2012-August 2021) were included. We excluded patients aged below 18 years undergoing concomitant coronary artery bypass grafting or atrial septal defect repair and those with MR etiology other than ARMR or DMR.

RESULTS

We included 35 patients with AFMR and 50 patients with DMR. Patient characteristics and postoperative outcomes were not significantly different between the two groups. Long-term outcomes revealed no significant differences in the ratio of cardiac mortality, stroke, or hospital readmission. However, after the maze procedure, the sinus rhythm restoration rate was significantly lower (62% vs. 28.5%, p < 0.001), a junctional rhythm state (p < 0.001) and permanent pacemaker insertion for sick sinus syndrome (SSS) (p = 0.03) were significantly more common in AFMR than DMR. On postoperative transthoracic echocardiography (TTE), the pulmonary artery systolic pressure was significantly less decreased in the AFMR group than in the DMR group compared with that on preoperative TTE (p = 0.04).

CONCLUSIONS

AFMR showed excellent mitral valve surgery outcomes, similar to DMR, but had a significantly higher risk of pacemaker insertion for SSS after the maze procedure.

Surgical outcome of mitral valve surgery in atrial functional mitral regurgitation compared with degenerative etiology

OBJECTIVE

To analyze and compare the outcomes of mitral valve surgery for atrial functional mitral regurgitation (AFMR) and for degenerative mitral regurgitation (DMR).

METHODS

Patients with AFMR or DMR who underwent mitral valve repair/replacement at 2 institutions between January 2012 and December 2022 were included. Patients <18 years of age and patients undergoing concomitant cardiac surgery (except for the maze procedure or tricuspid annuloplasty) were excluded. Propensity score analysis was used to adjust for baseline differences.

RESULTS

A total of 642 patients were enrolled. After propensity score analysis, 164 patients were classified into the DMR group, and 82 patients were classified into the AFMR group. All matched patients in both groups had atrial fibrillation. In DMR and AFMR, the 5-year freedom from readmission for heart failure and cardiac death was 96.3% in the DMR group versus 88.6% in the AFMR group (P = .045) and freedom from readmission for cardiac death in the 2 groups was 100% and 90.0%, respectively (P = .002). The recurrence rate of significant mitral regurgitation (MR) after mitral valve repair was not significantly different between the 2 groups (P = .699, log-rank test), and the 5-year freedom from MR recurrence (moderate or greater) was 89.8% and 93.0%, respectively. After the maze procedure, significantly more patients in the AFMR group than the DMR group were in junctional rhythm (49.1% vs 3.3%; P < .001) and required permanent pacemaker insertion during the follow-up period (11.4% vs 1.5% after 5 years; P = .041, log-rank test).

CONCLUSIONS

AFMR was associated with acceptable outcomes of mitral valve surgery, and mitral valve repair is a good treatment option. However, significantly more patients were in junctional rhythm after the maze procedure, needing more permanent pacemaker insertion.

Surgical strategy and outcomes for atrial functional mitral regurgitation: All functional mitral regurgitation is not the same!

OBJECTIVE

Functional mitral regurgitation (FMR) is a cardiac pathology that causes the mitral valve to malfunction, leading to mitral regurgitation (MR). The optimal strategy for FMR remains unclear, and FMR outcomes are poor. All etiologies of FMR might not be the same, and subdividing patients with FMR caused by atrial (AFMR) versus ventricular FMR pathology might be important. Herein, we present outcomes of patients with AFMR to define this "new" population.

METHODS

Data of patients who underwent mitral valve repair for MR from 2000 to 2020 were reviewed. Patients with degenerative/myxomatous disease, ejection fraction <50% (ventricular FMR), and miscellaneous etiologies including endocarditis and rheumatic disease were excluded to isolate a population of "pure" AFMR patients. Descriptive characteristics and outcomes data were analyzed.

RESULTS

Among 123 total AFMR patients, mean preoperative left atrial dimensions were enlarged to 4.9 (95% CI, 4.7-5.0) cm, whereas mean preoperative left ventricular diastolic dimensions remained near normal at 5.0 (95% CI, 4.9-5.2) cm. Preoperative atrial fibrillation was noted in 61% (74/123). Echocardiogram was performed in 58% (71/123) of patients at a median of 569 (interquartile range, 75-1782) days after surgery. Of those, 72% (51/71) had trivial or no MR, 22% (16/71) mild, and only 6% (4/71) moderate or greater MR. Only 1.6% (2/123) required redo mitral valve reoperation. Estimated 5-year survival was 74%.

CONCLUSIONS

Patients with AFMR do well after mitral valve repair using an annuloplasty ring, with low rates of reoperation, mortality, and recurrence of MR. Mitral annuloplasty should be considered the surgical therapy of choice for AFMR.

Parameters of the mitral apparatus in patients with ischemic and nonischemic dilated cardiomyopathy

The mitral valve apparatus is a complex structure consisting of several coordinating components: the annulus, two leaflets, the chordae tendineae, and the papillary muscles. Due to the intricate interplay between the mitral valve and the left ventricle, a disease of the latter may influence the normal function of the former. As a consequence, valve insufficiency may arise despite the absence of organic valve disease. This is designated as functional or secondary mitral regurgitation, and it arises from a series of distortions to the valve components. This narrative review describes the normal anatomy and the pathophysiology behind the mitral valve changes in ischemic and non-ischemic dilated cardiomyopathies. It also explains the value of a complete multiparametric assessment of this structure. Not only must an assessment include quantitative measures of regurgitation, but also various anatomical parameters from the mitral apparatus and left ventricle, since they carry prognostic value and are predictors of mitral valve repair success and durability.

An Image-Based Computational Fluid Dynamics Study of Mitral Regurgitation in Presence of Prolapse

PURPOSE

In this work we performed an imaged-based computational study of the systolic fluid dynamics in presence of mitral valve regurgitation (MVR). In particular, we compared healthy and different regurgitant scenarios with the aim of quantifying different hemodynamic quantities.

METHODS

We performed computational fluid dynamic (CFD) simulations in the left ventricle, left atrium and aortic root, with a resistive immersed method, a turbulence model, and with imposed systolic wall motion reconstructed from Cine-MRI images, which allowed us to segment also the mitral valve. For the regurgitant scenarios we considered an increase of the heart rate and a dilation of the left ventricle.

RESULTS

Our results highlighted that MVR gave rise to regurgitant jets through the mitral orifice impinging against the atrial walls and scratching against the mitral valve leading to high values of wall shear stresses (WSSs) with respect to the healthy case.

CONCLUSION

CFD with prescribed wall motion and immersed mitral valve revealed to be an effective tool to quantitatively describe hemodynamics in case of MVR and to compare different regurgitant scenarios. Our findings highlighted in particular the presence of transition to turbulence in the atrium and allowed us to quantify some important cardiac indices such as cardiac output and WSS.

Functional mitral regurgitation combined with increased early diastolic transmitral velocity to early mitral annulus diastolic velocity ratio is associated with a poor prognosis in patients with shock

BACKGROUND

Functional mitral regurgitation (FMR) is common in critically ill patients and may cause left atrial (LA) pressure elevation. This study aims to explore the prognostic impact of synergistic LA pressure elevation and FMR in patients with shock.

METHODS

We retrospectively screened 130 consecutive patients of 175 patients with shock from April 2016 to June 2017. The incidence and impact of FMR and early diastolic transmitral velocity to early mitral annulus diastolic velocity ratio (E/e') ≥ 4 within 6 h of shock on the prognosis of patients were evaluated. Finally, the synergistic effect of FMR and E/e' were assessed by combination, grouping, and trend analyses.

RESULTS

Forty-four patients (33.8%) had FMR, and 15 patients (11.5%) had E/e' elevation. A multivariate analysis revealed FMR and E/e' as independent correlated factors for 28-day mortality (P = 0.043 and 0.028, respectively). The Kaplan-Meier survival analysis revealed a significant difference in survival between patients with and without FMR (χ2 = 7.672, P = 0.006) and between the E/e' ≥ 14 and E/e' < 14 groups (χ2 = 19.351, P < 0.010). Twenty-eight-day mortality was significantly different among the four groups (χ2 = 30.141, P < 0.010). The risk of 28-day mortality was significantly higher in group 4 (E/e' ≥ 14 with FMR) compared with groups 1 (E/e' < 14 without FMR) and 2 (E/e' < 14 with FMR) (P = 0.001 and 0.046, respectively).

CONCLUSIONS

Patients with shock can be identified by the presence of FMR. FMR and E/e' are independent risk factors for a poor prognosis in these patients, and prognosis is worst when FMR and E/e' ≥ 14 are present. It may be possible to improve prognosis by reducing LA pressure and E/e'.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03082326.

Potential mechanism of left ventricular spherical remodeling: association of mitral valve complex-myocardium longitudinal tissue remodeling mismatch

Since mitral valve (MV) complex (MVC) longitudinally bridges left ventricular (LV) base end and its middle, insufficient MVC longitudinal tissue length (TL) elongation relative to whole LV myocardial longitudinal TL elongation could limit LV-base-longitudinal-TL elongation, leading to predominant LV-base-transverse-TL elongation, constituting LV spherical remodeling. In 30 patients with dilated cardiomyopathy (DCM), 30 with aortic regurgitation (AR), and 30 controls, LV sphericity, LV-apex- or base-transverse- and longitudinal-TL, MVC-longitudinal-TL, and whole-LV-longitudinal-TL were measured by three-dimensional (3D) echocardiography. Ratio of each measure versus mean normal value (i.e., LV-apex-transverse-TL ratio) was considered to express the directional and regional tissue elongation. [LV-base-longitudinal-TL ratio/global-LV-TL ratio] and [MVC-longitudinal-TL ratio/whole-LV-longitudinal-TL ratio] were obtained as the degree of LV-base-longitudinal-TL or MVC-longitudinal-TL elongation relative to the whole LV elongation. LV-apex-transverse-, LV-apex-longitudinal-, and LV-base-transverse-TL ratios were significantly increased (1.27 to 1.42, P < 0.01) in both DCM and AR, while the LV-base-longitudinal-TL ratio was not increased in DCM [1.04 ± 0.19, not significant (ns)] and only modestly increased in AR (1.12 ± 0.21, P < 0.01). Whole-LV-longitudinal-TL ratio was significantly increased in both DCM and AR (1.22 ± 0.18 and 1.20 ± 0.16, P < 0.01), while MVC-longitudinal-TL ratio was not or only modestly increased in both groups (1.07 ± 0.15, ns, and 1.12 ± 0.17, P = 0.02, respectively). Multivariable analysis revealed that LV sphericity was independently related to a reduced [LV-base-longitudinal-TL ratio/global-LV-TL ratio] (standard β = -0.42, P < 0.01), which was further related to a reduced [MVC-longitudinal-TL ratio/whole-LV-longitudinal-TL ratio] (standard β = 0.72, P < 0.01). These are consistent with the hypothesis that relatively less MVC-longitudinal-TL elongation in the process of primary LV myocardial tissue elongation may limit LV-base-longitudinal-TL elongation, contributing to LV spherical remodeling.NEW & NOTEWORTHY Left ventricular (LV) spherical remodeling is associated with poor prognosis and less-effective cardiac performance, which commonly develops in dilated cardiomyopathy. However, its mechanism remains unclear. We hypothesized and subsequently clarified that less mitral valve complex (MVC) tissue longitudinal elongation relative to whole LV myocardial tissue longitudinal elongation is related to disproportionately less LV base longitudinal versus transverse myocardial tissue elongation, constituting spherical remodeling. This study suggests modification of MVC tissue elongation could be potential therapeutic targets.

Partial Annuloplasty Rings in the Repair of Functional Ischemic Mitral Regurgitation

Background

Acute myocardial infarction (MI) is the leading cause of worldwide cardiac morbidities and mortalities. Mitral regurgitation (MR) is a common complication of MI. The severity of ischemic MR (IMR) can range widely, both clinically and hemodynamically. Mitral valve (MV) repair by lifting annuloplasty is a surgical procedure used to correct the pathology of IMR. The immediate outcomes of this technique have not yet been determined. The present study, therefore, evaluated the immediate results of MV annuloplasty performed to complement MV repair in patients with IMR.

Methodology

All adult patients with IMR who underwent lifting posterior mitral annuloplasty (LPMA) plus concomitant coronary artery bypass grafting (CABG) were included. Immediate outcomes were evaluated by transesophageal color Doppler echocardiography. The frequency of successful outcomes was compared in patients with different baseline characteristics.

Results

Posterior mitral annuloplasty was successful in 93.1% of patients, including in 92.8% of men and 94.1% of women. The percentages of successful immediate outcomes differed significantly in patients with and without diabetes and hypertension, and in patients with two- and three-vessel disease.

Conclusion

LPMA resulted in a high percentage of successful immediate outcomes in patients with IMR. Further studies should compare rates of immediate, intermediate, and late outcomes of this technique.

Advanced Imaging Techniques for Mitral Regurgitation

Mitral regurgitation (MR) is one of the most commonly encountered valvular lesions in clinical practice. MR can be either primary (degenerative) or secondary (functional) depending on the etiology of MR and the pathology of the mitral valve (MV). Echocardiography is the primary diagnostic tool for MR and is key in determining this etiology as well as MR severity. While clinicians usually turn to 2 Dimensional echocardiography as first-line imaging, 3 Dimensional echocardiography (3DE) has continually shown to be superior in terms of describing MV anatomy and pathology. This review article elaborates on 3DE techniques, modalities, and advances in software. Furthermore, the article demonstrates how 3DE has reformed MR evaluation and has played a vital role in determining patient management.