Disproportionate mitral regurgitation: another myth? A critical appraisal of echocardiographic assessment of functional mitral regurgitation

Mitral Regurgitation "Proportionality" in Functional Mitral Regurgitation and Outcomes After Mitral Valve Transcatheter Edge-to-Edge Repair: A Systematic Review and Meta-Analysis

Background

Certain patients with functional mitral regurgitation survive longer with fewer heart failure hospitalizations after undergoing transcatheter edge-to-edge repair (TEER); however, clinical markers identifying who will benefit have not been established. The 'proportionality' of mitral regurgitation (MR) severity compared to left ventricular size has been hypothesized to predict clinical outcome.

Methods

We sought to combine existing studies to compare outcomes between 'proportionate' MR and 'disproportionate' MR in patients undergoing TEER. PubMed and Medline were searched from January 2018 until May 2023. Data was extracted and synthesized by 2 independent authors using random effects models with risk ratios (RRs) for binary outcomes. The primary outcome was a combined endpoint of all-cause mortality or heart failure hospitalization (ACM/HFH). Other outcomes of interest included ACM and residual >2+ MR after TEER.

Results

Six trials with a total of 1594 patients (mean age 71 years, 66% male) were included, which assessed MR proportionality using either a ratio of estimated regurgitant orifice area to left ventricular end-diastolic volume (EROA:LVEDV) or regurgitant fraction. Seven hundred and five (mean age 70 years, 75% male) were classified as proportionate MR, and 889 (mean age 72 years, 60% male) had disproportionate MR. There was no significant association between MR proportionality (by EROA:LVEDV) and ACM (RR 0.79, 95% confidence interval [CI] 0.44-1.42). Proportionality did not significantly associate with ACM/HFH, though there were divergent effect signals when proportionality was measured by EROA:LVEDV (RR 0.80, 95% CI 0.45-1.44) or regurgitant fraction (RR 1.48, 95% CI 0.53-4.11). Disproportionate MR showed a greater association with residual MR > 2+ post-TEER that did not meet statistical significance (RR 1.86, 95% CI 0.77-4.49).

Conclusions

In patients undergoing TEER for functional mitral regurgitation, MR proportionality was not significantly associated with ACM/HFH, all-cause mortality, or residual MR.

Expert proposal to analyze the combination of aortic and mitral regurgitation in multiple valvular heart disease by comprehensive echocardiography

The assessment of valvular pathologies in multiple valvular heart disease by echocardiography remains challenging. Data on echocardiographic assessment-especially in patients with combined aortic and mitral regurgitation-are rare in the literature. The proposed integrative approach using semi-quantitative parameters to grade the severity of regurgitation often yields inconsistent findings and results in misinterpretation. Therefore, this proposal aims to focus on a practical systematic echocardiographic analysis to understand the pathophysiology and hemodynamics in patients with combined aortic and mitral regurgitation. The quantitative approach of grading the regurgitant severity of each compound might be helpful in elucidating the scenario in combined aortic and mitral regurgitation. To this end, both the individual regurgitant fraction of each valve and the total regurgitant fraction of both valves must be determined. This work also outlines the methodological issues and limitations of the quantitative approach by echocardiography. Finally, we present a proposal that enables verifiable assessment of regurgitant fractions. The overall interpretation of echocardiographic results includes the symptomatology of patients with combined aortic and mitral regurgitation and the individual treatment options with respect to their individual risk. In summary, a reproducible, verifiable, and transparent in-depth echocardiographic investigation might ensure consistent hemodynamic plausibility of the quantitative results in patients with combined aortic and mitral regurgitation.

Challenges and pitfalls in classification of disproportionate mitral regurgitation

The concept of disproportionate mitral regurgitation (dispropMR) has been introduced to identify patients with functional mitral regurgitation (MR) who benefit from percutaneous treatment. We aimed to examine echocardiographic characteristics behind this entity. We retrospectively included 172 consecutive patients with reduced left ventricular ejection fraction (LVEF), and more than mild MR referred to clinically indicated echocardiography. According to the proportionality ratio (effective regurgitant orifice area (EROA)/left ventricular end-diastolic volume (LVEDV)) patients were divided into dispropMR and proportionate MR (propMR) group. Potential factors which might affect proportionality definition were analyzed. 55 patients (32%) had dispropMR. Discrepant grading of MR severity was observed when using regurgitant volume (RegVol) by proximal isovelocity surface area (PISA) method or volumetric method, with significant discordance only in dispropMR (p < 0.001). Patients with dispropMR had more frequently left ventricular foreshortened images for LVEDV calculation than patients with propMR (p = 0.003), resulting in smaller LVEDV in dispropMR group. DispropMR group had more substantial dynamic variation of regurgitant flow compared to propMR. Accordingly, EROA was consistently overestimated by standard single-point PISA method compared to serial PISA method. This was more pronounced in dispropMR (bias:10.5 ± 28.3 mm2) compared to propMR group (bias:6.4 ± 12.8 mm2). DispropMR may be found in roughly one third of clinically indicated echocardiographic studies in patients with reduced LVEF and more than mild MR. EROA overestimation due to dynamic variation of regurgitant flow and LVEDV underestimation due to LV foreshortening were more frequently found in dispropMR. Our results indicate that methodological limitations of echocardiographic MR grading could not be neglected in classifying the proportionality of MR.

Perspectives on Secondary Mitral Regurgitation in Heart Failure

PURPOSE OF THE REVIEW

This review focuses on broader perspectives of mitral regurgitation (MR) in patients with heart failure.

RECENT FINDINGS

The ratio of regurgitant volume to end-diastolic volume appears to help identify patients who may benefit from valve interventions. Secondary MR is not only attributed to geometric changes of the LV but also related to the structural changes in the mitral valve that include fibrosis of the mitral leaflets and changes in the extracellular matrix. The transition from mild to severe secondary MR can occur at different rates, from a slow LV remodeling process to a more abrupt process precipitated by an inciting event such as atrial fibrillation. Septal flash and apical rocking, two new visual markers of LV mechanical dyssynchrony, appear to be predictive of MR reduction following cardiac resynchronization therapy. Optimal guideline-directed medical therapy has been shown to decrease the severity of secondary MR effectively. A theoretical framework to characterize secondary MR as it relates to the onset of MR is proposed. Type A: Early onset of MR contemporaneous with myocardial injury. The maladaptive LV remodeling occurs in parallel with MR. Type B: LV remodeling proceeds without significant MR until the LV is moderately dilated, which coincides with or without inciting factors such as atrial fibrillation. Type C: LV remodeling proceeds after myocardial injury without significant MR until the LV is severely dilated. MR is a late manifestation of LV remodeling.

Mitral Regurgitation in Female Patients: Sex Differences and Disparities

Mitral regurgitation is the most common valvular disease, particularly in older adults. Recent literature has consistently supported that there are significant differences in mitral regurgitation outcomes between male and female patients and that this is likely multifactorial. Numerous sex differences in anatomy and pathophysiology may play a role in delayed diagnoses, referrals, and treatments for female patients. Despite the recognition of these discrepancies in the literature, many guidelines that steer clinical care do not incorporate these factors into society recommendations. Identifying and validating sex-specific diagnostic parameters and increasing the representation of female patients in trials of new mitral regurgitation treatment modalities are key factors in improving outcomes for female patients.

Quantification of primary mitral regurgitation by echocardiography: A practical appraisal

The accurate quantification of primary mitral regurgitation (MR) and its consequences on cardiac remodeling is of paramount importance to determine the best timing for surgery in these patients. The recommended echocardiographic grading of primary MR severity relies on an integrated multiparametric approach. It is expected that the large number of echocardiographic parameters collected would offer the possibility to check the measured values regarding their congruence in order to conclude reliably on MR severity. However, the use of multiple parameters to grade MR can result in potential discrepancies between one or more of them. Importantly, many factors beyond MR severity impact the values obtained for these parameters including technical settings, anatomic and hemodynamic considerations, patient's characteristics and echocardiographer' skills. Hence, clinicians involved in valvular diseases should be well aware of the respective strengths and pitfalls of each of MR grading methods by echocardiography. Recent literature highlighted the need for a reappraisal of the severity of primary MR from a hemodynamic perspective. The estimation of MR regurgitation fraction by indirect quantitative methods, whenever possible, should be central when grading the severity of these patients. The assessment of the MR effective regurgitant orifice area by the proximal flow convergence method should be used in a semi-quantitative manner. Furthermore, it is crucial to acknowledge specific clinical situations in MR at risk of misevaluation when grading severity such as late-systolic MR, bi-leaflet prolapse with multiple jets or extensive leak, wall-constrained eccentric jet or in older patients with complex MR mechanism. Finally, it is debatable whether the 4-grades classification of MR severity would be still relevant nowadays, since the indication for mitral valve (MV) surgery is discussed in clinical practice for patients with 3+ and 4+ primary MR based on symptoms, specific markers of adverse outcome and MV repair probability. Primary MR grading should be seen as a continuum integrating both quantification of MR and its consequences, even for patients with presumed "moderate" MR.

Transcatheter edge-to-edge mitral valve repair in mitral regurgitation: current status and future prospects

INTRODUCTION

Mitral regurgitation (MR) is associated with substantial morbidity and mortality. Within the past 15 years, mitral valve edge-to-edge repair (M-TEER) has developed from an experimental approach to a guideline-recommended, safe, and effective treatment option for patients with severe primary or secondary mitral regurgitation.

AREAS COVERED

This review covered relevant publications of M-TEER and summarizes the development of M-TEER devices within the last 15 years. It outlines anatomical challenges which drove the evolution of M-TEER devices, provides an overview about the current state of clinical application and research, and offers an outlook into the future of transcatheter mitral valve treatment.

EXPERT OPINION

The development and refinement of new M-TEER device generations offer the possibility to treat a wide range of mitral valve anatomies. Choosing the best device for the individual anatomic properties of the patients and considering comorbidities is the key to maximized MR reduction, minimalized complication rates, and thus optimized postinterventional prognosis. Independent from prognostic implications, quality of life has become an important patient-centered outcome that can be improved by M-TEER in virtually all patients treated.

Tricuspid Regurgitation in Acute Heart Failure: Predicting Outcome Using Novel Quantitative Echocardiography Techniques

Background: The prognostic impact of tricuspid regurgitation (TR) in acute heart failure (AHF) remains uncertain. Methods: We retrospectively assessed 418 consecutive AHF patients who underwent comprehensive echocardiographic assessment within 24 h of study recruitment. TR was quantitatively assessed with 3 guideline-directed measures: regurgitant volumes (RgVol), effective regurgitant orifice area (ERO) and vena contracta (VC) diameter. Disproportionate TR was assessed by the ratio of the VC diameter to the tricuspid annulus diameter (VC/TA) ≥ 0.24. Results: The prevalence of significant (i.e., >mild) TR differed when various standard assessment parameters were applied to quantification: RgVol 50.3% (173/344), ERO 75.6% (260/344) and VC diameter 94.6% (335/354). None were able to delineate those at excess risk of all-cause 2-year mortality using guideline-directed cut-offs of mild, moderate and severe TR. Using a cut-off of VC/TA ≥ 0.24, we identified that 36.9% (130/352) had “disproportionate” TR. Disproportionate TR was associated with an excess risk of mortality at 2 years compared to proportionate TR; HR 1.48 (95% CI 1.06−2.06 [p = 0.02]) which was not significant on multivariate assessment (p = 0.94). Conclusions: TR was not associated with outcome in AHF using guideline measures. A new assessment of “Disproportionate” TR carries a higher risk than proportionate TR but was not related to outcome based on multivariate analysis. Further research is needed to quantify TR more effectively to identify cut-offs for future guidelines and disproportionate TR may be an important part of Heart Failure 2.0.

Medical Therapy for Functional Mitral Regurgitation

Functional mitral regurgitation (FMR) can be broadly categorized into 2 main groups: ventricular and atrial, which often coexist. The former is secondary to left ventricular remodeling usually in the setting of heart failure with reduced ejection fraction or less frequently due to ischemic papillary muscle remodeling. Atrial FMR develops due to atrial and annular dilatation related to atrial fibrillation/flutter or from increased atrial pressures in the setting of heart failure with preserved ejection fraction. Guideline-directed medical therapy is the first step and prevails as the mainstay in the treatment of FMR. In this review, we address the medical therapeutic options for FMR management and highlight a targeted approach for each FMR category. We further address important clinical and echocardiographic characteristics to aid in determining when medical therapy is expected to have a low yield and an appropriate window for effective interventional approaches exists.

Cardiac Surgery 2021 Reviewed

PubMed displayed more than 35,000 hits for the search term "cardiac surgery AND 2021." We used the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) approach and selected relevant publications for a results-oriented summary. As in recent years, we reviewed the fields of coronary and conventional valve surgery and their overlap with their interventional alternatives. COVID reduced cardiac surgical activity around the world. In the coronary field, the FAME 3 trial dominated publications by practically repeating SYNTAX, but with modern stents and fractional flow reserve (FFR)-guided percutaneous coronary interventions (PCIs). PCI was again unable to achieve non-inferiority compared with coronary artery bypass graft surgery (CABG) in patients with triple-vessel disease. Survival advantages of CABG over PCI could be linked to a reduction in myocardial infarctions and current terminology was criticized because the term "myocardial revascularization" is not precise and does not reflect the infarct-preventing collateralization effect of CABG. In structural heart disease, new guidelines were published, providing upgrades of interventional treatments of both aortic and mitral valve disease. While for aortic stenosis, transcatheter aortic valve implantation (TAVI) received a primary recommendation in older and high-risk patients; recommendations for transcatheter mitral edge-to-edge treatment were upgraded for patients considered inappropriate for surgery. For heart team discussions it is important to know that classic aortic valve replacement currently provides strong signals (from registry and randomized evidence) for a survival advantage over TAVI after 5 years. This article summarizes publications perceived as important by us. It can neither be complete nor free of individual interpretation, but provides up-to-date information for decision-making and patient information.

[Functional Diagnostics by Rational Echocardiography]

Functional diagnostics by rational echocardiography are the base of a verifiable and reliable analysis of ventricular and valvular function. The most important functional parameters in echocardiography are cardiac volumes - especially total and effective left ventricular stroke volume -, global longitudinal strain, effective orifica areas in valvular stenoses and effective regurgitant volumes, regurgitant fraction and regurgitant orifice areas in valvular regurgitations. Standardized documentation and correct measurements are the prerequisites for accurate echocardiographic estimations. In addition, optimization of image quality supports the correctness of measurements to ensure plausibility of hemodynamics in each individual patient. However, measurements of cardiac volumes by planimetry are error-prone. In addition, calculation of the effective orifice areas using the continuity equation needs methodological accuracy and standardization. Finally, assessment of regurgitant volumes, regurgitant fraction, and regurgitant orifice is often inconsistent with stable hemodynamic conditions - especially by functional assessment the 2D-PISA method. Thus, functional diagnostics by echocardiography in valvular heart diseases should focus on a plausible hemodynamic assessment.

Plausible Functional Diagnostics by Rational Echocardiography in the Assessment of Valvular Heart Disease - Role of Quantitative Echocardiography in the Assessment of Mitral Regurgitation

The echocardiographic assessment of valvular heart diseases is the basic analysis of valvular defects next to clinical investigation and stethoscopy. Severity of mitral regurgitation (MR) is usually estimated by an integrated approach using semi quantitative parameters and is still one of the biggest challenges of echocardiography. Quantitative echocardiographic analysis of MR severity often fails to describe comprehensible hemodynamic conditions. However, comprehensive echocardiography based on standardized image acquisition and proper image quality is required to properly assess hemodynamic parameter comparable to cardiac magnetic resonance tomography. This review focuses on the uncertainty of MR severity assessed by echocardiography in recent trials of interventional MR treatment. In addition, the necessity to provide plausible echocardiographic data for individual decision making is highlighted. In conclusion, plausible functional diagnostics by rational echocardiography is a prerequisite in patients with valvular heart diseases.

Long-term clinical and haemodynamic results after transcatheter annuloplasty for secondary mitral regurgitation

AIMS

The study sought to investigate the long-term outcome after transcatheter mitral valve annuloplasty for secondary mitral regurgitation (MR).

METHODS AND RESULTS

Consecutive patients with symptomatic secondary MR undergoing transcatheter mitral valve annuloplasty with the Carillon device at Leipzig University Hospital between 2012 and 2018 were studied prospectively. Left ventricular (LV) function and MR severity were quantified by standardized echocardiography. 33 patients were included. Mean age was 75 ± 10 years, and 20 patients were women. A Society of Thoracic Surgeons score of 8.1 ± 7.2% indicated high-risk status. In 24 patients, MR resulted from LV remodelling and dysfunction, eight suffered from left atrial dilatation, and one patient had MR due to combined primary and secondary aetiology. LV ejection fraction at baseline was (median) 38% [inter-quartile range (IQR) 30-49%]. During the mean follow-up time of 45 ± 20 months, 17 patients died, two patients withdraw consent, and four patients were lost. Of the remaining patients, four were hospitalized for decompensated heart failure. Two of these patients underwent additional transcatheter edge-to-edge mitral valve repair. At follow-up, New York Heart Association (NYHA) functional class improved from 95% in Class III/IV at baseline to 70% in Class I/II with no patients in NYHA Class IV (P < 0.0001). Mitral regurgitant volume was reduced from 27 mL (IQR 25-42 mL) to 8 mL (IQR 3-17 mL) (P = 0.018) and regurgitant fraction from 42% (IQR 34-54%) to 11% (IQR 8-24%) (P = 0.014). LV end-diastolic volume index [92 mL/m2 (IQR 74-107 mL/m2 ) vs. 67 mL/m2 (IQR 46-101 mL/m2 ), P = 0.065] and end-systolic volume index [50 mL/m2 (IQR 44-69 mL/m2 ) vs. 32 mL/m2 (IQR 20-53 mL/m2 ), P = 0.037] decreased. Total stroke volume remained unchanged [38 mL/m2 (IQR 33-43 mL/m2 ) vs. 33 mL/m2 (IQR 26-44 mL/m2 ), P = 0.695], while LV ejection fraction increased [43% (IQR 35-49%) vs. 54% (IQR 46-57%), P = 0.014]. Forward stroke volume, heart rate, and forward cardiac output were not significantly altered.

CONCLUSIONS

Among high-risk patients undergoing transcatheter mitral valve annuloplasty for symptomatic secondary MR, mortality was ~50% at 4 years. In the surviving patients, reduced MR severity was associated with reduced NYHA functional class, reverse LV remodelling, and improved LV function.

Echocardiographic assessment of mitral regurgitation: discussion of practical and methodologic aspects of severity quantification to improve diagnostic conclusiveness

The echocardiographic assessment of mitral valve regurgitation (MR) by characterizing specific morphological features and grading its severity is still challenging. Analysis of MR etiology is necessary to clarify the underlying pathological mechanism of the valvular defect. Severity of mitral regurgitation is often quantified based on semi-quantitative parameters. However, incongruent findings and/or interpretations of regurgitation severity are frequently observed. This proposal seeks to offer practical support to overcome these obstacles by offering a standardized workflow, an easy means to identify non-severe mitral regurgitation, and by focusing on the quantitative approach with calculation of the individual regurgitant fraction. This work also indicates main methodological problems of semi-quantitative parameters when evaluating MR severity and offers appropriateness criteria for their use. It addresses the diagnostic importance of left-ventricular wall thickness, left-ventricular and left atrial volumes in relation to disease progression, and disease-related complaints to improve interpretation of echocardiographic findings. Finally, it highlights the conditions influencing the MR dynamics during echocardiographic examination. These considerations allow a reproducible, verifiable, and transparent in-depth echocardiographic evaluation of MR patients ensuring consistent haemodynamic plausibility of echocardiographic results.

A review of the pivotal role of cardiac MRI in mitral valve regurgitation

Cardiac imaging is the cornerstone of defining the etiology, quantification, and management of mitral regurgitation (MR). This continues to be even more so the case with emerging transcatheter techniques to manage MR. Transthoracic echocardiography remains the first-line imaging modality to assess MR but has limitations. Cardiac MRI(CMR) provides the advantages of quantitative nonvisual estimation, 3D volumetric data, late gadolinium, T1, and extracellular volume measurements to comprehensively assess mitral valvular pathology, cardiac remodeling, and the prognostic impact of therapies. This review describes the superiority, technical aspects and growing evidence behind CMR, and lays the roadmap for the future of CMR in MR.