Primary mitral valve regurgitation: Update and review

Novel 3-dimensional effective regurgitation orifice area quantification serves as a reliable tool to identify severe mitral valve regurgitation

A precise quantification of mitral regurgitation (MR) severity is essential for treatment and outcome of patients with MR. 3D echocardiography facilitates estimation of MR but selection of patients with necessity of invasive treatment remains challenging. We investigate effective regurgitation orifice area (EROA) quantification by 3D compared to 2D echocardiography in patients with MR and highlight the improved discrimination of MR severity. We consecutively enrolled fifty patients with primary or secondary and at least moderate MR undergoing 2D and 3D colour Doppler echocardiography prior to transcatheter edge-to-edge repair (TEER). Improved accuracy of MR grading using 3D vena contracta area (VCA) as an estimate of EROA was compared to 2D proximal isovelocity surface area (PISA) quantification method and a multiparameter reference standard. Quantification of EROA remarkably varies between 2D and 3D echocardiography and the discrimination between moderate and severe MR was significantly (p = 0.001) different using 2D PISA or 3D VCA, respectively. 3D VCA correlated significantly (r = 0.501, p < 0.001) better with the pre-defined MR severity. We detected crucial differences in the correct identification of severe MR between 2D and 3D techniques, thus 2D PISA significantly (p < 0.0001) underestimates EROA due to clinical and morphological parameters. The assessment of 3D VCA resulted in improved diagnostic accuracy.

Catheter ablation for atrial fibrillation in patients with significant mitral regurgitation: A systematic review and meta-analysis

BACKGROUND

Atrial fibrillation (AF) is commonly associated with cardiac structural abnormalities including mitral regurgitation (MR). Contemporary guidelines recommend consideration of early rhythm control strategies including catheter ablation (CA) for AF. However, the long-term efficacy of CA is highly variable across studies and patient populations, and the effect of coexisting MR on AF recurrence remains unclear.

OBJECTIVE

A systematic review and meta-analysis was performed to determine the impact of significant MR (defined as ≥moderate) on AF recurrence rate after CA and whether CA for AF is associated with significant changes in the severity of MR.

METHODS

A systematic search of PubMed, Embase, Web of Science, and Cochrane databases for all English-language studies published to December 31, 2023, was performed.

RESULTS

A total of 17 studies (N = 2624 patients) were retained for meta-analysis. The pooled recurrence proportion of AF after CA in patients with baseline significant MR was 36% (95% CI, 27%-46%) compared with 27% (14%-41%) in patients without. The pooled hazard ratio (95% CI) for AF recurrence after CA in the presence of significant MR was 2.47 (1.52-4.01; P < .001; Egger test P value, .0583). The pooled proportion of patients who witnessed MR improvement to nonsignificant (ie,

CONCLUSION

Baseline significant MR was independently predictive of AF recurrence rate after CA. Despite the increased AF recurrence rates after CA associated with significant MR, CA with maintenance of sinus rhythm appeared to improve the severity of MR, suggesting a possible induction of reverse positive atrial and mitral valvular remodeling.

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Key Words

• Atrial fibrillation
• Catheter ablation
• Mitral regurgitation
• Pulmonary vein isolation
• Review

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Affiliation(s)

Ross A Okazaki Department of Medicine, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts
Lillian C Flashner Department of Medicine, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts
Scott Kinlay Department of Medicine, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts; Department of Medicine, VA Boston Healthcare System, Boston, Massachusetts; Department of Medicine, Harvard Medical School, Boston, Massachusetts; Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts
Adelqui O Peralta Department of Medicine, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts; Department of Medicine, VA Boston Healthcare System, Boston, Massachusetts; Department of Medicine, Harvard Medical School, Boston, Massachusetts
Peter S Hoffmeister Department of Medicine, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts; Department of Medicine, VA Boston Healthcare System, Boston, Massachusetts; Department of Medicine, Harvard Medical School, Boston, Massachusetts
Hirad Yarmohammadi Department of Medicine, Columbia University, New York, New York
Jacob Joseph Department of Medicine, Brown University, Providence, Rhode Island; Department of Medicine, VA Providence Healthcare System, Providence, Rhode Island
Matthew F Yuyun Department of Medicine, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts; Department of Medicine, VA Boston Healthcare System, Boston, Massachusetts; Department of Medicine, Harvard Medical School, Boston, Massachusetts.

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Large Animal Translational Validation of 3 Mitral Valve Repair Operations for Mitral Regurgitation Using a Mitral Valve Prolapse Model: A Comprehensive In Vivo Biomechanical Engineering Analysis

BACKGROUND

Various mitral repair techniques have been described. Though these repair techniques can be highly effective when performed correctly in suitable patients, limited quantitative biomechanical data are available. Validation and thorough biomechanical evaluation of these repair techniques from translational large animal in vivo studies in a standardized, translatable fashion are lacking. We sought to evaluate and validate biomechanical differences among different mitral repair techniques and further optimize repair operations using a large animal mitral valve prolapse model.

METHODS

Male Dorset sheep (n=20) had P2 chordae severed to create the mitral valve prolapse model. Fiber Bragg grating force sensors were implanted to measure chordal forces. Ten sheep underwent 3 randomized, paired mitral valve repair operations: neochord repair, nonresectional leaflet remodeling, and triangular resection. The other 10 sheep underwent neochord repair with 2, 4, and 6 neochordae. Data were collected at baseline, mitral valve prolapse, and after each repair.

RESULTS

All mitral repair techniques successfully eliminated regurgitation. Compared with mitral valve prolapse (0.54±0.18 N), repair using neochord (0.37±0.20 N; P=0.02) and remodeling techniques (0.30±0.15 N; P=0.001) reduced secondary chordae peak force. Neochord repair further decreased primary chordae peak force (0.21±0.14 N) to baseline levels (0.20±0.17 N; P=0.83), and was associated with lower primary chordae peak force compared with the remodeling (0.34±0.18 N; P=0.02) and triangular resectional techniques (0.36±0.27 N; P=0.03). Specifically, repair using 2 neochordae resulted in higher peak primary chordal forces (0.28±0.21 N) compared with those using 4 (0.22±0.16 N; P=0.02) or 6 neochordae (0.19±0.16 N; P=0.002). No difference in peak primary chordal forces was observed between 4 and 6 neochordae (P=0.05). Peak forces on the neochordae were the lowest using 6 neochordae (0.09±0.11 N) compared with those of 4 neochordae (0.15±0.14 N; P=0.01) and 2 neochordae (0.29±0.18 N; P=0.001).

CONCLUSIONS

Significant biomechanical differences were observed underlying different mitral repair techniques in a translational large animal model. Neochord repair was associated with the lowest primary chordae peak force compared to the remodeling and triangular resectional techniques. Additionally, neochord repair using at least 4 neochordae was associated with lower chordal forces on the primary chordae and the neochordae. This study provided key insights about mitral valve repair optimization and may further improve repair durability.

Disparities in Mitral Valve Disease Associated with Heart Failure

Heart failure (HF) affects millions of people around the world and is a prevalent health issue in the United States. In many cases, HF has an intricate connection with mitral valvular disease (MVD), which can alter a patient's disease course. Factors such as gender, race, ethnicity, and social determinants of health impact the prevalence, etiology, and treatment of MVD associated with HF. This literature review examines the connection between MVD and HF among adult patients, considering MVD as both a cause and an outcome of HF. This article also identifies the differences in epidemiology and treatment of MVD associated with HF across different gender, ethnicity, race, and socioeconomic groups. This is in an effort to not only identify currently overlooked disparities but to highlight potential ways to improve them. MVD was analyzed based on its hemodynamic subtypes, mitral regurgitation (MR) and mitral stenosis (MS), as these subtypes encompass different etiologies of MVD. The purpose of this article was to identify broad disparities in MVD in association with HF in the adult population. The results of this study found stark differences between prevalence, treatment, and disease outcomes across groups. Women and Black patients were identified as high-risk for under-utilization and prescription delay of treatment options. Women were often treated at more advanced stages of MVD, while treatment was often delayed in Black patient populations. Factors such as these impact treatment outcomes. Conversely, men and White patients were identified as lower-risk groups for treatment inadequacies and poor HF and MVD related outcomes. Socioeconomic status (SES) was also found to play a role, with low SES being a risk factor for developing rheumatic heart disease. Low SES groups are also more likely to develop HF, which predisposes to secondary MR. Despite general knowledge of these disparities, few studies analyze HF and MVD for specific groups. This literature review is thus necessary to identify current inequities in care and underscore potential solutions to raise awareness for further research efforts and funding. This analysis identifies MVD treatment guidelines and contributing social determinants of health as areas that must be addressed to minimize HF and MVD disparities.

Biomechanical engineering analysis of neochordae length's impact on chordal forces in mitral repair

OBJECTIVES

Artificial neochordae implantation is commonly used for mitral valve (MV) repair. However, neochordae length estimation can be difficult to perform. The objective was to assess the impact of neochordae length changes on MV haemodynamics and neochordal forces.

METHODS

Porcine MVs (n = 6) were implanted in an ex vivo left heart simulator. MV prolapse (MVP) was generated by excising at least 2 native primary chordae supporting the P2 segments from each papillary muscle. Two neochordae anchored on each papillary muscle were placed with 1 tied to the native chord length (exact length) and the other tied with variable lengths from 2× to 0.5× of the native length (variable length). Haemodynamics, neochordal forces and echocardiography data were collected.

RESULTS

Neochord implantation repair successfully eliminated mitral regurgitation with repaired regurgitant fractions of approximately 4% regardless of neochord length (P < 0.01). Leaflet coaptation height also significantly improved to a minimum height of 1.3 cm compared with that of MVP (0.9 ± 0.4 cm, P < 0.05). Peak and average forces on exact length neochordae increased as variable length neochordae lengths increased. Peak and average forces on the variable length neochordae increased with shortened lengths. Overall, chordal forces appeared to vary more drastically in variable length neochordae compared with exact length neochordae.

CONCLUSIONS

MV regurgitation was eliminated with neochordal repair, regardless of the neochord length. However, chordal forces varied significantly with different neochord lengths, with a preferentially greater impact on the variable length neochord. Further validation studies may be performed before translating to clinical practices.

Left atrial strain analysis in the realm of pediatric cardiology: Advantages and implications

BACKGROUND

Left atrial (LA) strain analysis has emerged as a noninvasive technique for assessing LA function and early detection of myocardial deformation. Recently, its application has also shown promise in the pediatric population, spanning diverse cardiac conditions that demand accurate and sensitive diagnostic measures.

OBJECTIVE

This research article endeavors to explore the role of LA strain parameters and contribute to the growing body of knowledge in pediatric cardiology, paving the way for more effective and tailored approaches to patient care.

METHODS

A comprehensive literature review was conducted to gather evidence from studies using echocardiographic strain imaging techniques across pediatric populations.

RESULTS

LA strain parameters exhibited greater sensitivity than conventional atrial function indicators, with early detection of diastolic dysfunction and LA remodeling in pediatric cardiomyopathy, children with multisystem inflammatory syndrome, rheumatic heart disease, as well as childhood renal insufficiency and obesity offering prognostic relevance as potential markers in these pediatric subpopulations. However, there remains a paucity of evidence concerning pediatric mitral valve pathology, justifying further exploration.

CONCLUSION

LA strain analysis carries crucial clinical and prognostic implications in pediatric cardiac conditions, with reliable accuracy and sensitivity to early functional changes.

Subvalvular techniques enhanced with endoscopic robotic mitral valve repair

Objective

Totally endoscopic intracardiac robotic surgery is generally limited to uncomplicated mitral valve surgery. With experience, our team has developed a more aggressive approach to robotic cardiac surgery that allows for repair of a broad spectrum of mitral valve pathologies. We report complex subvalvular procedural advancements associated with this approach secondary to enhanced team experience and capabilities.

Methods

All robotic mitral procedures performed by a 2-surgeon team in a quaternary care medical center from July 2011 to May 2022 were reviewed. Natural language-processing techniques were used to analyze operative reports for subvalvular repair techniques. Complex subvalvular techniques included papillary muscle repositioning, division of secondary anterior leaflet chordae, septal myomectomy, division of aberrant left ventricular muscle band attachments, and left ventricular patch reconstruction. The surgical experience was divided into 2 periods: early robotic experience (pre-2018) versus late (2018 onwards). Baseline demographics, outcomes, and subvalvular techniques were analyzed and compared.

Results

A total of 1287 intracardiac robotic operations were performed by a 2-surgeon team. Thirty-day mortality was 0.6% (8/1287). Mitral valve repair was performed in 1024 patients. The mean age was 61 years (range, 18-90 years), and 15% were >75 years old; 29 patients (2.8%) had previously undergone cardiac surgery. There was a significant increase with experience in the application of advanced subvalvular techniques between the early versus late period (52.3% [268/512] vs 74.2% [380/512] (P < .001)).

Conclusions

An experienced 2-surgeon team can perform progressively more complex robotic subvalvular repair techniques. These subvalvular techniques are a surrogate for team proficiency and capabilities.

An analytical, mathematical annuloplasty ring curvature model for planning of valve-in-ring transcatheter mitral valve replacement

OBJECTIVES

An increasing number of high-risk patients with previous mitral valve annuloplasty require transcatheter mitral valve replacement due to recurrent regurgitation. Annulus dilation with a transcatheter balloon is often performed before valve-in-ring transcatheter mitral valve replacement, which is believed to reduce misalignment and paravalvular leakage, yet little evidence exists to support this practice. Our objective was to generate intuitive annuloplasty ring analyses for improved valve-in-ring transcatheter mitral valve replacement planning.

METHODS

We generated a mathematical model that calculates image-tracked differential ring curvature to build quantifications for improved planning for valve-in-ring procedures. Carpentier-Edwards Physio M24 and M30 (n = 2 each), Physio II M24 and M26 (n = 3 each), LivaNova AnnuloFlex M26 (n = 2), and Edwards Geoform M28 (n = 2) rings were tested with a 30-mm Toray Inoue balloon inflated to maximum rated pressures.

RESULTS

Curvature variance reduces with larger ring sizes, indicating that larger rings are initially more circular than smaller ones. Evaluated semi-rigid and rigid rings showed little to no difference between pre- and post-dilation states. Annuloflex rings (flexible band) showed a postdilation variance reduction of 32.83% (P < .001) followed by an increase after 10 minutes of relaxation that was still reduced by 19.62% relative to the initial state (P < .001).

CONCLUSIONS

We discovered that balloon dilation does not significantly deform evaluated semi-rigid or rigid rings at maximum rated balloon pressures. This may mean that dilation for these conditions before valve-in-ring transcatheter mitral valve replacement is unnecessary. Our mathematical approach creates a foundation for extended classification of this practice, providing meaningful quantification of ring geometry.

Cardiogenic Pneumonia: Unilateral Pulmonary Edema Secondary to Severe Eccentric Mitral Regurgitation

Mitral regurgitation (MR), whether primary or secondary, stems from functional or anatomical impairment of components of the mitral apparatus resulting in abnormal blood flow to the left atrium during systole. A common complication is bilateral pulmonary edema (PE), which, in rare instances, may be unilateral and easily misdiagnosed. This case presents an elderly male with unilateral lung infiltrates and progressive exertional dyspnea with the failed treatment of pneumonia. Additional workup, including a transesophageal echocardiogram (TEE), showed severe eccentric MR. He underwent mitral valve (MV) replacement with significant improvement in symptoms.

Looking towards the future: patient-specific computational modeling to optimize outcomes for transcatheter mitral valve repair

Severe mitral valve regurgitation (MR) is a heart valve disease that progresses to end-stage congestive heart failure and death if left untreated. Surgical repair or replacement of the mitral valve (MV) remains the gold standard for treatment of severe MR, with repair techniques aiming to restore the native geometry of the MV. However, patients with extensive co-morbidities may be ineligible for surgical intervention. With the emergence of transcatheter MV repair (TMVR) treatment paradigms for MR will evolve. The longer-term outcomes of TMVR and its effectiveness compared to surgical repair remain unknown given the differing patient eligibility for either treatment at this time. Advances in computational modeling will elucidate answers to these questions, employing techniques such as finite element method and fluid structure interactions. Use of clinical imaging will permit patient-specific MV models to be created with high accuracy and replicate MV pathophysiology. It is anticipated that TMVR technology will gradually expand to treat lower-risk patient groups, thus pre-procedural computational modeling will play a crucial role guiding clinicians towards the optimal intervention. Additionally, concerted efforts to create MV models will establish atlases of pathologies and biomechanics profiles which could delineate which patient populations would best benefit from specific surgical vs. TMVR options. In this review, we describe recent literature on MV computational modeling, its relevance to MV repair techniques, and future directions for translational application of computational modeling for treatment of MR.

Usefulness of P-wave peak time as an electrocardiographic parameter in predicting left ventricular diastolic dysfunction in patients with mitral regurgitation

INTRODUCTION

Conventional Doppler measurements have limitations in predicting left ventricular diastolic dysfunction (LVDD) in patients with mitral regurgitation (MR). Recently, electrocardiographic P-wave peak time (PWPT) has been proposed as a parameter of detecting LVDD. This study aimed to evaluate the association between PWPT and left ventricular end-diastolic pressure (LVEDP) in patients with MR.

METHODS

We performed echocardiography and cardiac catheterization in 82 patients with moderate or severe MR. We classified patients into two groups: low LVEDP group (L-LVEDP) (LVEDP <16 mmHg, n = 40) and high LVEDP group (H-LVEDP) (LVEDP ≥16 mmHg, n = 42). We evaluated LVDD and PWPT based on echocardiographic and electrocardiographic findings in both groups.

RESULTS

The PWPT in lead II (PWPT_II ) was significantly longer in patients in the H-LVEDP group than in those in the L-LVEDP group (67 vs. 47 ms, p < .001). Using correlation analysis, LVEDP was positively correlated with PWPT_II (r = .577, p < .001). Using multivariate analysis, PWPT_II was found to be an independent predictor of increased LVEDP (95% CI: 0.1030-0.110; p < .001). Using receiver operating characteristic (ROC) curve analysis, the optimal cutoff value of PWPT_II for predicting elevated LVEDP was 58.9 ms, with a sensitivity of 80.0% and a specificity of 73.8% (area under curve: 0.809, 95% CI: 0.713-0.905).

CONCLUSION

To the best of our knowledge, this is the first study to assess the effect of a significant valvular disease on PWPT in lead II. These findings suggest that prolonged PWPT_II may be an independent predictor of increased LVEDP in patients with moderate or severe MR.

Late plasma exosome microRNA-21-5p depicts magnitude of reverse ventricular remodeling after early surgical repair of primary mitral valve regurgitation

Introduction

Primary mitral valve regurgitation (MR) results from degeneration of mitral valve apparatus. Mechanisms leading to incomplete postoperative left ventricular (LV) reverse remodeling (Rev-Rem) despite timely and successful surgical mitral valve repair (MVR) remain unknown. Plasma exosomes (pEXOs) are smallest nanovesicles exerting early postoperative cardioprotection. We hypothesized that late plasma exosomal microRNAs (miRs) contribute to Rev-Rem during the late postoperative period.

Methods

Primary MR patients (n = 19; age, 45-71 years) underwent cardiac magnetic resonance imaging and blood sampling before (T0) and 6 months after (T1) MVR. The postoperative LV Rev-Rem was assessed in terms of a decrease in LV end-diastolic volume and patients were stratified into high (HiR-REM) and low (LoR-REM) LV Rev-Rem subgroups. Isolated pEXOs were quantified by nanoparticle tracking analysis. Exosomal microRNA (miR)-1, -21-5p, -133a, and -208a levels were measured by RT-qPCR. Anti-hypertrophic effects of pEXOs were tested in HL-1 cardiomyocytes cultured with angiotensin II (AngII, 1 μM for 48 h).

Results

Surgery zeroed out volume regurgitation in all patients. Although preoperative pEXOs were similar in both groups, pEXO levels increased after MVR in HiR-REM patients (+0.75-fold, p = 0.016), who showed lower cardiac mass index (-11%, p = 0.032). Postoperative exosomal miR-21-5p values of HiR-REM patients were higher than other groups (p < 0.05). In vitro, T1-pEXOs isolated from LoR-REM patients boosted the AngII-induced cardiomyocyte hypertrophy, but not postoperative exosomes of HiR-REM. This adaptive effect was counteracted by miR-21-5p inhibition.

Summary/Conclusion

High levels of miR-21-5p-enriched pEXOs during the late postoperative period depict higher LV Rev-Rem after MVR. miR-21-5p-enriched pEXOs may be helpful to predict and to treat incomplete LV Rev-Rem after successful early surgical MVR.

Percutaneous Repair of Mitral Regurgitation: A Comprehensive Review of Literature

Mitral regurgitation is the most common valvular disease in the US and the second most common worldwide. Left untreated, it can lead to the development of heart failure, giving rise to increased mortality rates. Mitral valve intervention is usually indicated in severe mitral regurgitation at the onset of symptoms, even if the function of the left ventricle is preserved. A surgical approach is generally favored according to current guidelines, with excellent clinical outcomes. However, the emergence of novel data from contemporary trials indicates that percutaneous, catheter-based approach may have similar improvements in mortality outcomes while maintaining a superior safety profile when compared to the surgical approach. Here, we discuss transcatheter mitral valve repair as a treatment option for mitral regurgitation and summarize the major clinical trials which were recently conducted on transcatheter repair.

Clinical Impact of Computational Heart Valve Models

This paper provides a review of engineering applications and computational methods used to analyze the dynamics of heart valve closures in healthy and diseased states. Computational methods are a cost-effective tool that can be used to evaluate the flow parameters of heart valves. Valve repair and replacement have long-term stability and biocompatibility issues, highlighting the need for a more robust method for resolving valvular disease. For example, while fluid-structure interaction analyses are still scarcely utilized to study aortic valves, computational fluid dynamics is used to assess the effect of different aortic valve morphologies on velocity profiles, flow patterns, helicity, wall shear stress, and oscillatory shear index in the thoracic aorta. It has been analyzed that computational flow dynamic analyses can be integrated with other methods to create a superior, more compatible method of understanding risk and compatibility.

Are There Any Differences in the Prognostic Value of Left Ventricular Ejection Fraction in Coronary Artery Disease Patients With or Without Moderate and Severe Mitral Regurgitation?

Background

Left ventricular ejection fraction (LVEF) is a vital variable to describe left ventricle systolic function and contractility of left ventricle. However, the association between LVEF and the prognostic effect in patients with moderate or severe mitral regurgitation (MR) is still controversial.

Methods

This study comprised 30,775 coronary artery disease (CAD) patients who underwent coronary arteriography (CAG) in the Cardiorenal ImprovemeNt (CIN) registry from January 2007 to December 2018. Patients were divided into none or mild MR group and moderate or severe MR group, and 3 levels of LVEF ≥50, 40–50%, and <40% were further distinguished according to hospital baseline. Univariate and multivariate Cox proportional analyses were used to investigate the association between LVEF levels and long-term all-cause mortality in patients with different MR severities.

Results

Of 30,775 CAD patients (62.9 ± 10.6 years, females 23.8%), 26,474 (86.0%) patients had none or mild MR. Compared with none or mild MR patients, patients with moderate or severe MR were older and had worse cardio-renal function. In multivariable Cox proportional analysis, LVEF <40% was independently associated with higher mortality compared with LVEF ≥ 50% in all kinds of MR severity {none or mild MR [adjusted hazard ratio (HR): 1.79; 95% CI: 1.56–2.05, p < 0.001], moderate or severe MR [adjusted HR: 1.57; 95% CI: 1.29–1.91, p < 0.001]}.

Conclusions

LVEF is a reliable prognostic index in CAD patients, even in those with moderate or severe MR. LVEF monitoring would still be clinically useful in CAD patients with moderate or severe MR. Clinical trials are needed to prospectively evaluate the optimal threshold for LVEF in patients with moderate or severe MR.

Impact of Chest Wall Conformation on the Outcome of Primary Mitral Regurgitation due to Mitral Valve Prolapse

Background

The possible influence of chest wall conformation on cardiovascular (CV) outcome of patients with mitral regurgitation (MR) due to mitral valve prolapse (MVP) has never been previously investigated.

Methods

This retrospective study included all consecutive symptomatic patients with MVP and moderate MR who underwent exercise stress echocardiography at our institution between February 2014 and February 2021. Modified Haller Index (MHI; chest transverse diameter over the distance between sternum and spine) was noninvasively assessed. During the follow-up, we evaluated the occurrence of any of the following: (1) CV hospitalization, (2) mitral valve (MV) surgery, and (3) cardiac death or sudden death.

Results

Four hundred and twenty-four consecutive patients (66.8 ± 11.5 years, 48.3% men) were retrospectively analyzed. Overall, MVP patients had concave-shaped chest wall (MHI = 2.55 ± 0.34) and were found with small cardiac chamber dimensions. During a mean follow-up time of 3.2 ± 1.7 years, no patients died, 55 patients were hospitalized due to CV events, and 20 patients underwent MV surgery. On multivariate Cox analysis, age (heart rate [HR] 1.05, 95% confidence interval [CI] 1.03-1.06), diabetes mellitus (HR 3.26, 95% CI 2.04-5.20), peak exercise-E/e' ratio (HR 1.07, 95%CI 1.05-1.09), and peak exercise-effective regurgitant orifice area (HR 2.53, 95% CI 1.83-3.51) were directly associated to outcome, whereas MHI (HR 0.15, 95%CI 0.07-0.33) and beta-blocker therapy (HR 0.26, 95% CI 0.19-0.36) showed strong inverse correlation. An MHI ≥2.7 showed 80% sensitivity and 100% specificity for predicting event-free survival (area under the curve = 0.98).

Conclusions

Symptomatic patients with moderate MR due to MVP and MHI ≥2.7 have an excellent prognosis over a medium-term follow-up. Noninvasive chest wall shape assessment should be encouraged in clinical practice.

Evaluation of Changes in the Cardiac Function before and after Transcatheter Edge-to-Edge Mitral Valve Repair in Healthy Dogs: Conventional and Novel Echocardiography

Mitral valve regurgitation is a common canine heart disease. Transcatheter Edge-to-Edge Repair (TEER) is a transcatheter, edge-to-edge mitral repair device that uses a hybrid approach. No detailed information has been published on the hemodynamic effect of TEER on cardiac function. The aim of this report is to provide a longitudinal observation of the cardiac functional changes observed after TEER implantation in normal dogs using traditional, two-dimensional speckle tracking, and color M-mode echocardiographic methods. In the current report, TEER was implanted into two healthy dogs under general anesthesia. An echocardiographic examination was performed at baseline and weekly postoperative follow-ups were conducted until the fourth week. Successful TEER implantation was achieved with a short operation time (98 and 63 min) in the two dogs. Functional mitral valve regurgitation, elevated E/e' ratio, elevated radial strain, and stable intraventricular pressure gradients (IVPG) were observed after the operation in the dogs. Mild non progressive mitral valve stenosis was observed in both dogs. TEER is a minimally invasive method for mitral valve surgery that necessitates more clinical trials. With longitudinal observation of heart function using novel approaches, better outcomes will be expected.

Ultrastructural Adaptation of the Cardiomyocyte to Chronic Mitral Regurgitation

Introduction: Mitral regurgitation (MR) imposes volume overload on the left ventricle (LV) and elevates wall stress, triggering its adverse remodeling. Pronounced LV dilation, minimal wall thinning, and a gradual decline in cardiac ejection fraction (EF) are observed. The structural changes in the myocardium that define these gross, organ level remodeling are not known. Cardiomyocyte elongation and slippage have both been hypothesized, but neither are confirmed, nor are the changes to the cardiomyocyte structure known. Using a rodent model of MR, we used immunohistochemistry and transmission electron microscopy (TEM) to describe the ultrastructural remodeling of the cardiomyocyte.

Methods: Twenty-four male Sprague-Dawley rats (350–400 g) were assigned to two groups: group (1) rats induced with severe MR (n = 18) and group (2) control rats that were healthy and age and weight matched (n = 6). MR was induced in the beating heart using a 23-G ultrasound-guided, transapical needle to perforate the anterior mitral leaflet, and the rats were followed to 2, 10, and 20 weeks (n = 6/time-point). Echocardiography was performed to quantify MR severity and to measure LV volume and function at each time-point. Explanted myocardial tissue were examined with TEM and immunohistochemistry to investigate the ultrastructural changes.

Results: MR induced rapid and significant increase in end-diastolic volume (EDV), with a 50% increase by 2 weeks, compared with control. Rise in end-systolic volume (ESV) was more gradual; however, by 20 weeks, both EDV and ESV in MR rats were increased by 126% compared with control. A significant decline in EF was measured at 10 weeks of MR. At the ultrastructural level, as early as 2 weeks after MR, cardiomyocyte elongation and increase in cross-sectional area were observed. TEM depicted sarcomere shortening, with loss of Z-line and I-band. Desmin, a cytoskeletal protein that is uniformly distributed along the length of the cardiomyocyte, was disorganized and localized to the intercalated disc, in the rats induced with MR and not in the controls. In the rats with MR, the linear registry of the mitochondrial arrangement along the sarcomeres was lost, with mitochondrial fragmentation, aggregation around the nucleus, and irregularities in the cristae.

Discussion: In the setting of chronic mitral regurgitation, LV dilatation occured by cardiomyocyte elongation, which manifests at the subcellular level as distinct ultrastructural alterations of the sarcomere, cytoskeleton, and mitochondria. Since the cytoskeleton not only provides tensegrity but has functional consequences on myocyte function, further investigation into the impact of cytoskeletal remodeling on progressive heart failure or recovery of function upon correcting the valve lesion are needed.

Alterations in Intracardiac Flow Patterns Affect Mitral Leaflets Dynamics in a Model of Ischemic Mitral Regurgitation

PURPOSE

This study was to evaluate the effects of ischemic mitral regurgitation (IMR) on vortex formation and leaflet dynamics using an established porcine infarct model of IMR.

METHODS

Using direct coronary ligation, five animals were subjected to a posterolateral myocardial infarction (MI) followed by an MRI at 12-weeks post MI. MR imaging consisted of 4D time-resolved left ventricular (LV) flow, full coverage 2D LV cine, and high resolution 2D cine of mitral valve dynamics. Five additional naïve animals underwent identical imaging protocols to serve as controls. Image analysis was performed to obtain mitral transvalvular flows as well as LV volumes throughout the cardiac cycle. In addition, anterior to posterior mid-leaflet tip distances were measured throughout the cardiac cycle for determination of temporal leaflet dynamics.

RESULTS

It was found IMR caused asymmetric vortex ring formation with the anterior vortex having a lower vorticity relative to its posterior counterpart. In contrast, normal ventricles create symmetric and tightly curled vortices in the basal chamber just underneath the mitral leaflets which conserve kinetic energy and aid in effective ejection. IMR animals were also evaluated for leaflet separation and were found to have a greater leaflet opening and achieved peak vorticity and peak leaflet opening later than control animals.

CONCLUSION

In conclusion, this study shows the effects that altered vortex formation, due to IMR, can have on ventricular filling and leaflet dynamics. These findings have important implications for understanding blood flow through the dilated heart and how ring annuloplasty and volume reduction interventions may influence mitral valve dynamics.

Machine Learning Prediction Models for Mitral Valve Repairability and Mitral Regurgitation Recurrence in Patients Undergoing Surgical Mitral Valve Repair

Background: Mitral valve regurgitation (MR) is the most common valvular heart disease and current variables associated with MR recurrence are still controversial. We aim to develop a machine learning-based prognostic model to predict causes of mitral valve (MV) repair failure and MR recurrence. Methods: 1000 patients who underwent MV repair at our institution between 2008 and 2018 were enrolled. Patients were followed longitudinally for up to three years. Clinical and echocardiographic data were included in the analysis. Endpoints were MV repair surgical failure with consequent MV replacement or moderate/severe MR (>2+) recurrence at one-month and moderate/severe MR recurrence after three years. Results: 817 patients (DS1) had an echocardiographic examination at one-month while 295 (DS2) also had one at three years. Data were randomly divided into training (DS1: n = 654; DS2: n = 206) and validation (DS1: n = 164; DS2 n = 89) cohorts. For intra-operative or early MV repair failure assessment, the best area under the curve (AUC) was 0.75 and the complexity of mitral valve prolapse was the main predictor. In predicting moderate/severe recurrent MR at three years, the best AUC was 0.92 and residual MR at six months was the most important predictor. Conclusions: Machine learning algorithms may improve prognosis after MV repair procedure, thus improving indications for correct candidate selection for MV surgical repair.

Hemodynamic and transcriptomic studies suggest early left ventricular dysfunction in a preclinical model of severe mitral regurgitation

OBJECTIVE

Primary mitral regurgitation is a valvular lesion in which the left ventricular ejection fraction remains preserved for long periods, delaying a clinical trigger for mitral valve intervention. In this study, we sought to investigate whether adverse left ventricular remodeling occurs before a significant fall in ejection fraction and characterize these changes.

METHODS

Sixty-five rats were induced with severe mitral regurgitation by puncturing the mitral valve leaflet with a 23-G needle using ultrasound guidance. Rats underwent longitudinal cardiac echocardiography at biweekly intervals and hearts explanted at 2 weeks (n = 15), 10 weeks (n = 15), 20 weeks (n = 15), and 40 weeks (n = 15). Sixty age- and weight-matched healthy rats were used as controls. Unbiased RNA-sequencing was performed at each terminal point.

RESULTS

Regurgitant fraction was 40.99 ± 9.40%, with pulmonary flow reversal in the experimental group, and none in the control group. Significant fall in ejection fraction occurred at 14 weeks after mitral regurgitation induction. However, before 14 weeks, end-diastolic volume increased by 93.69 ± 52.38% (P < .0001 compared with baseline), end-systolic volume increased by 118.33 ± 47.54% (P < .0001 compared with baseline), and several load-independent pump function indices were reduced. Transcriptomic data at 2 and 10 weeks before fall in ejection fraction indicated up-regulation of myocyte remodeling and oxidative stress pathways, whereas those at 20 and 40 weeks indicated extracellular matrix remodeling.

CONCLUSIONS

In this rodent model of mitral regurgitation, left ventricular ejection fraction was preserved for a long duration, yet rapid and severe left ventricular dilatation, and biological remodeling occurred before a clinically significant fall in ejection fraction.

Left ventricle assessment by three-dimensional HeartModel software in different types of mitral valve prolapse (Barlow's disease and fibroelastic deficiency) with severe mitral regurgitation

BACKGROUND

Mitral valve prolapse (MVP) is the most common cause of isolated mitral regurgitation (MR) requiring surgical repair. Therapeutic interventions should be considered before irreversible left ventricular (LV) dysfunction in asymptomatic patients. Measurement of LV volume and function is very important. Because of two-dimensional (2D) echocardiography limitations, three-dimensional (3D) measurement is preferred on the strength of its speed, accuracy, and reproducibility, which are comparable with those of magnetic resonance imaging (MRI).

METHODS

This study was conducted between April 2018 and February 2019 on 50 patients with different MVP types and severe MR scheduled for valve surgery at Rajaie Cardiovascular Research Center, Tehran, Iran, with the aid of the HeartModelAnatomical intelligence (A.I.) (EPIQ 7: new 3D software) for measurement of LV volume indices and function.

RESULTS

Patients with the Barlow syndrome had a greater drop in LV ejection fraction (LVEF) than those with fibroelastic deficiency (FED) (57.05% ± 6.00% vs. 65.00% ± 4.08%; P = 0.001). LV volume was larger in patients with flail mitral valve (MV) than in those with non-flail MV (165 cc vs. 118 cc; P = 0.001). LVEF declined more in patients with the involvement of both leaflets than in those with the involvement of the anterior leaflet alone (56.00% ± 7.10% vs. 57.70% ± 4.30%; P = 0.021).

CONCLUSION

The LVEF drop was more remarkable in patients with the Barlow syndrome (both flail and non-flail MV) than in those with FED. It is, therefore, advisable that such patients be monitored more meticulously via the 3D HeartModelA.I. method in terms of LVEF and LV size to prevent irreversible effects on LV function and to reduce mortality.

Characterization of Degenerative Mitral Valve Disease: Differences between Fibroelastic Deficiency and Barlow's Disease

Degenerative mitral valve disease causing mitral valve prolapse is the most common cause of primary mitral regurgitation, with two distinct phenotypes generally recognized with some major differences, i.e., fibroelastic deficiency (FED) and Barlow's disease. The aim of this review was to describe the main histological, clinical and echocardiographic features of patients with FED and Barlow's disease, highlighting the differences in diagnosis, risk stratification and patient management, but also the still significant gaps in understanding the exact pathophysiology of these two phenotypes.

Point-of-care Ultrasound in the Evaluation of Mitral Valve Regurgitation and Mitral Annular Calcification

Case Presentation

A 77-year-old female presented to the emergency department (ED) with chest pain. Cardiac point-of-care ultrasound (POCUS) was performed and demonstrated a hyperechoic structure on the posterior leaflet of the mitral valve. Admission to cardiology and echocardiogram revealed moderately decreased mobility of the posterior leaflet, mitral annular calcification, and severe mitral regurgitation.

Discussion

These findings highlight the role of POCUS in identifying mitral valve pathology in the ED, ultimately leading to appropriate disposition and management. Mitral annular calcification can lead to significant manifestations including mitral stenosis or regurgitation, and advanced cases have been associated with an increased risk of infective endocarditis, thrombosis, and arrhythmia.

Right Ventricle Mechanics and Function during Stress in Patients with Asymptomatic Primary Moderate to Severe Mitral Regurgitation and Preserved Left Ventricular Ejection Fraction

Background and objectives. Mitral regurgitation (MR) is usually dynamic and increasing with exertion. Stress may provoke symptoms, cause the progression of pulmonary hypertension (PH) and unmask subclinical changes of the left and right ventricle function. The aim of this study was to evaluate changes of right ventricle (RV) functional parameters during stress and to find out determinants of RV function in patients with MR. Materials and methods. We performed a prospective study that included patients with asymptomatic primary moderate to severe MR and preserved left ventricular (LV) ejection fraction (EF) at rest (≥60%). Conventional 2D echocardiography at rest and during stress (bicycle ergometry) and offline speckle tracking analysis were performed. Results. 80 patients were included as MR (50) and control (30) groups. Conventional functional and myocardial deformation parameters of RV were similar in both groups at all stages of exercise (p > 0.05). The grade of MR (p = 0.004) and higher LV global longitudinal strain (p = 0.037) contributed significantly to the changes of tricuspid annular plane systolic excursion (TAPSE) from rest to peak stress. Changes of MR ERA from the rest to peak stress were related to RV free wall longitudinal strain (FWLS) and four chambers longitudinal stain (4CLS) at rest (p = 0.011; r = −0.459 and p = 0.001; r = −0.572, respectively). Significant correlations between LV EF, stroke volume, cardiac output and RV fractional area change, S′, TAPSE, FWLS, 4CLS were obtained. However, systolic pulmonary artery pressure and RV functional, deformation parameters were not related (p > 0.05). Conclusions. Functional parameters of LV during exercise and severity of MR were significant determinants of RV function while PH has no correlation with it in patients with primary asymptomatic moderate to severe MR.