Regurgitant Volume/Left Ventricular End-Diastolic Volume Ratio: Prognostic Value in Patients With Secondary Mitral Regurgitation

Left Atrium: A New Prognostic Marker and Therapeutic Target in Secondary Mitral Regurgitation?

Mitral regurgitation (MR) is one of the most common valvular abnormalities worldwide and can be subdivided into primary and secondary causes. Atrial MR consists of a novel type of secondary MR (SMR), most often observed in patients with AF and heart failure with preserved ejection fraction. The main pathophysiological mechanism of atrial MR is mitral valve annular dilatation. Recently published studies have highlighted the clinical significance of left atrium (LA) evaluation in the early diagnosis and prognosis of patients with primary MR. However, there are little data regarding the role of the LA in SMR. The present literature review aims to elucidate the use of the echocardiographic parameters regarding LA evaluation in the prognosis prediction and therapeutic strategy of patients with SMR.

Aortic stiffness plays a role in the discrepancy between mitral valve lesion severity and hemodynamic burden of secondary mitral regurgitation

BACKGROUND

By the framework of proportionate/disproportionate secondary mitral regurgitation (sMR), disproportionate sMR is characterized by a low left ventricular stroke volume (SV) and an out of proportion regurgitant fraction (RF) for the same effective regurgitant orifice area (EROA). The degree of aortic stiffness is a determinant of the ventricular forward SV. We aim to analyze the importance of aortic stiffness in influencing the discrepancy between measures of mitral valve lesion severity (EROA) and sMR hemodynamic burden (regurgitant volume [RV] and RF).

METHODS

We enrolled stable patients with heart failure with reduced ejection fraction (HFrEF) and at least mild sMR. Mitral EROA, RV, RF and aortic pulse wave velocity (PWV) were measured by echocardiography. We defined three groups based on the degree of actual RF deviation from RF estimated by the linear regression equation of RF on EROA (concordant, low-discordant [residuals lower-than -5%] and high-discordant RF [residuals higher-than 5%]).

RESULTS

117 patients were analyzed (68±13 years; female 30%; LVEF 33±8%; EROA 16±12mm2; RV 24±15 ml; RF 27±13%; PWV 6.6 ± 3.2 m/s). LVEF, end-diastolic-volume and EROA didn't differ among groups. PWV and RV were higher in patients with high-discordant RF (p ≤ 0.01), whereas total left ventricular-SV and left ventricular outflow tract-SV (LVOT-SV) were lower (p ≤ 0.0004). PWV was associated with LVOT-SV (r=-0.3;p = 0.0008) and RV (r = 0.3;p = 0.0009). High-discordant RF was predicted by PWV (p = 0.001) independently of LVOT-SV and RV.

CONCLUSION

In this HFrEF cohort with sMR, higher PWV was associated with higher-than-expected RF for a given EROA. Aortic stiffness might play a role in the discrepancy between mitral valve lesion severity and sMR hemodynamic burden.

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.

Morphological and functional types of tricuspid regurgitation: prognostic value in patients undergoing tricuspid annuloplasty during left-sided valvular surgery

BACKGROUND

The nonuniform benefit of tricuspid annuloplasty may be explained by the proportionality of tricuspid regurgitation (TR) severity to right ventricular (RV) area. The purpose of this study was to delineate distinct morphological phenotypes of functional TR and investigate their prognostic implications in patients undergoing tricuspid annuloplasty during left-sided valvular surgery.

METHODS

The ratios of pre-procedural effective regurgitant orifice area (EROA) with right ventricular end-diastolic area (RVDA) were retrospectively assessed in 290 patients undergoing tricuspid annuloplasty. Based on optimal thresholds derived from penalized splines and maximally selected rank statistics, patients were stratified into proportionate (EROA/RVDA ratio ≤ 1.74) and disproportionate TR (EROA/RVDA ratio > 1.74).

RESULTS

Overall, 59 (20%) and 231 (80%) patients had proportionate and disproportionate TR, respectively. Compared to those with proportionate TR, patients with disproportionate TR were older, had a higher prevalence of atrial fibrillation, lower pulmonary pressures, more impaired RV function, and larger tricuspid leaflet tenting area. Over a median follow-up of 4.1 years, 79 adverse events (47 heart failure hospitalizations and 32 deaths) occurred. Patients with disproportionate TR had higher rates of adverse events than those with proportionate TR (32% vs 10%; P = 0.001) and were independently associated with poor outcomes on multivariate analysis. TR proportionality outperformed guideline-based classification of TR severity in outcome prediction and provided incremental prognostic value to both the EuroSCORE II and STS score (incremental χ2 = 6.757 and 9.094 respectively; both P < 0.05).

CONCLUSIONS

Disproportionate TR is strongly associated with adverse prognosis and may aid patient selection and risk stratification for tricuspid annuloplasty with left-sided valvular surgery.

Patient-Specific Quantitative In-Vivo Assessment of Human Mitral Valve Leaflet Strain Before and After MitraClip Repair

PURPOSE

Mitral regurgitation (MR) is a highly prevalent and deadly cardiac disease characterized by improper mitral valve (MV) leaflet coaptation. Among the plethora of available treatment strategies, the MitraClip is an especially safe option, but optimizing its long-term efficacy remains an urgent challenge.

METHODS

We applied our noninvasive image-based strain computation pipeline [1] to intraoperative transesophageal echocardiography datasets taken from ten patients undergoing MitraClip repair, spanning a range of MR etiologies and MitraClip configurations. We then analyzed MV leaflet strains before and after MitraClip implementation to develop a better understanding of (1) the pre-operative state of human regurgitant MV, and (2) the MitraClip's impact on the MV leaflet deformations.

RESULTS

The MV pre-operative strain fields were highly variable, underscoring both the heterogeneity of the MR in the patient population and the need for patient-specific treatment approaches. Similarly, there were no consistent overall post-operative strain patterns, although the average A2 segment radial strain difference between pre- and post-operative states was consistently positive. In contrast, the post-operative strain fields were better correlated to their respective pre-operative strain fields than to the inter-patient post-operative strain fields. This quantitative result implies that the patient specific pre-operative state of the MV guides its post-operative deformation, which suggests that the post-operative state can be predicted using pre-operative data-derived modelling alone.

CONCLUSIONS

The pre-operative MV leaflet strain patterns varied considerably across the range of MR disease states and after MitraClip repair. Despite large inter-patient heterogeneity, the post-operative deformation appears principally dictated by the pre-operative deformation state. This novel finding suggests that though the variation in MR functional state and MitraClip-induced deformation were substantial, the post-operative state can be predicted from the pre-operative data alone. This study suggests that, with use of larger patient cohort and corresponding long-term outcomes, quantitative predictive factors of MitraClip durability can be identified.

Clinical Utility of Three-Dimensional Echocardiography in the Evaluation of Mitral Valve Disease: Tips and Tricks

Although real-time 3D echocardiography (RT3DE) has only been introduced in the last decades, its use still needs to be improved since it is a time-consuming and operator-dependent technique and acquiring a good quality data can be difficult. Moreover, the additive value of this important diagnostic tool still needs to be wholly appreciated in clinical practice. This review aims at explaining how, why, and when performing RT3DE is useful in clinical practice.

Secondary mitral regurgitation: Maintaining coherence with the American Society of Echocardiography grading guidelines, which proportionality concept best predicts prognosis in the real world?

INTRODUCTION

Proportionality of secondary mitral regurgitation (sMR) may be a key factor in deciding whether a patient may benefit from mitral intervention. The aim of this study was to evaluate the prognostic value of two different concepts of proportionality and assess their ability to improve MR stratification proposed by the American Society of Echocardiography (ASE) guidelines.

METHODS

We conducted a retrospective analysis in patients with reduced left ventricular ejection fraction (LVEF) (<50%) and at least mild sMR. Proportionality status was calculated using formulas proposed by a) Grayburn et al. - disproportionate sMR defined as EROALVEDV >0.14; b) Lopes et al. - disproportionate sMR whenever measured EROA>theoretical EROA (determined as 50%×LVEF×LVEDVMitralVTI). Primary endpoint was all-cause mortality.

RESULTS

A total of 572 patients (69±12 years; 76% male) were included. Mean LVEF was 33±9%, with a median left ventricular end-diastolic volume of 174 mL [136;220] and a median effective regurgitant orifice area of 14 mm² [8;22]. During mean follow-up of 4.1±2.7 years, there were 254 deaths. There was considerable disagreement (p<0.001) between both formulas: of 96 patients with disproportionate sMR according to Lopes' criteria, 46 (48%) were considered proportionate according to Grayburn's; and of 62 patients with disproportionate sMR according to Grayburn's, 12 (19%) were considered proportionate according to Lopes' formula. In multivariate analysis, only Lopes' definition of disproportionate sMR maintained independent prognostic value (hazard ratio 1.5; 95% confidence interval 1.07-2.1, p=0.018) and improved the risk stratification of ASE sMR classification.

CONCLUSION

Of the two formulas available to define disproportionate sMR, Lopes' model emerged as the only one with independent prognostic value while improving the risk stratification proposed by the ASE guidelines.

Delayed hospitalisation for heart failure after transcatheter repair or medical treatment for secondary mitral regurgitation: a landmark analysis of the MITRA-FR trial

BACKGROUND

In the MITRA-FR trial, transcatheter mitral valve repair (TMVR) was not associated with a 2-year clinical benefit in patients with secondary mitral regurgitation (SMR).

AIMS

This landmark analysis aimed at investigating a potential reduction of the hospitalisation rate for heart failure (HF) between 12 and 24 months after inclusion in the MITRA-FR trial in patients randomised to the intervention group (TMVR with the MitraClip device), as compared with patients randomised to the control group (guideline-directed medical therapy [GDMT]).

METHODS

The MITRA-FR trial randomised 307 patients with SMR for TMVR on top of GDMT (TMVR group; n=152) or for GDMT alone (control group; n=155). We conducted a 12-month landmark analysis in surviving patients who were not hospitalised for HF within the first 12 months of follow-up. The primary endpoint was the 1-year cumulative number of HF hospitalisations.

RESULTS

A total of 140 patients (TMVR group: 67; GDMT group: 73) were selected for this landmark analysis with similar characteristics at inclusion in the trial. The primary endpoint was 28 events per 100 patient-years in the TMVR group, as compared with 60 events per 100 patient-years in the GDMT group (hazard ratio [HR] 0.46, 95% confidence interval [CI]: 0.20-1.02; p=0.057).

CONCLUSIONS

In this landmark analysis of the MITRA-FR trial, the cumulative rate of HF hospitalisation between 12 and 24 months among patients treated with TMVR on top of GDMT was approximately half as many as those of patients treated with GDMT alone, a difference which did not reach statistical significance in the setting of a low number of events.

Focus on Diagnosis and Prognosis to Guide Timing of Intervention in Valvular Heart Disease

Purpose of Review

The present article reviews the role of multimodality imaging to improve risk stratification and timing of intervention in patients with valvular heart disease (VHD), and summarizes the latest developments in transcatheter valve interventions.

Recent Findings

Growing evidence suggests that intervention at an earlier stage may improve outcomes of patients with significant VHD. Multimodality imaging, including strain imaging and tissue characterization with cardiac magnetic resonance imaging, has the ability to identify early markers of myocardial damage and can help to optimize the timing of intervention. Transcatheter interventions play an increasing role in the treatment of patients who remain at high surgical risk or present at a late stage of their disease.

Summary

Multimodality imaging identifies markers of cardiac damage at an early stage in the development of VHD. Together with technological innovations in the field of percutaneous valvular devices, these developments have the potential to improve current management and outcomes of patients with significant VHD.

Practical Echocardiographic Approach of the Regurgitant Mitral Valve Assessment

Mitral regurgitation is the second-most frequent valvular heart disease in Europe after degenerative aortic stenosis. It is associated with significant morbidity and mortality, and its prevalence is expected to increase with population aging. Echocardiography is the first diagnostic approach to assess its severity, constituting a challenging process in which a multimodality evaluation, integrating quantitative, semiquantitative and qualitative methods, as well as a detailed evaluation of the morphology and function of both left ventricle and atria is the key. In this review, we would like to provide a practical diagnosis approach on the mitral valve regurgitation mechanism, severity quantification, and planning of future therapeutic options.

Disproportionate Mitral Regurgitation Determines Survival in Acute Heart Failure

Objectives: To assess the prevalence and impact of mitral regurgitation (MR) on survival in patients presenting to hospital in acute heart failure (AHF) using traditional echocardiographic assessment alongside more novel indices of proportionality.

Background: It remains unclear if the severity of MR plays a significant role in determining outcomes in AHF. There is also uncertainty as to the clinical relevance of indexing MR to left ventricular volumes. This concept of disproportionality has not been assessed in AHF.

Methods: A total of 418 consecutive patients presenting in AHF over 12 months were recruited and followed up for 2 years. MR was quantitatively assessed within 24 h of recruitment. Standard proximal isovelocity surface area (PISA) and a novel proportionality index of effective regurgitant orifice/left ventricular end-diastolic volume (ERO/LVEDV) >0.14 mm²/ml were used to identify severe and disproportionate MR.

Results: Every patient had MR. About 331/418 (78.9%) patients were quantifiable by PISA. About 165/418 (39.5%) patients displayed significant MR. A larger cohort displayed disproportionate MR defined by either a proportionality index using ERO/LVEDV > 0.14 mm²/ml or regurgitant volumes/LVEDV > 0.2 [217/331 (65.6%) and 222/345 (64.3%), respectively]. The LVEDV was enlarged in significant MR−129.5 ± 58.95 vs. 100.0 ± 49.91 ml in mild, [p < 0.0001], but remained within the normal range. Significant MR was associated with a greater mortality at 2 years {44.2 vs. 34.8% in mild MR [hazard ratio (HR) 1.39; 95% CI: 1.01–1.92, p = 0.04]}, which persisted with adjustment for comorbid conditions (HR; 1.43; 95% CI: 1.04–1.97, p = 0.03). Disproportionate MR defined by ERO/LVEDV >0.14 mm²/ml was also associated with worse outcome [42.4 vs. 28.3% (HR 1.62; 95% CI 1.12–2.34, p = 0.01)].

Conclusions: MR was a universal feature in AHF and determines outcome in significant cases. Furthermore, disproportionate MR, defined either by effective regurgitant orifice (ERO) or volumetrically, is associated with a worse prognosis despite the absence of adverse left ventricular (LV) remodeling. These findings outline the importance of adjusting acute volume overload to LV volumes and call for a review of the current standards of MR assessment.

Clinical Trial Registration:https://clinicaltrials.gov/ct2/show/NCT02728739, identifier NCT02728739.

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.

Assessing proportionate and disproportionate functional mitral regurgitation with individualized thresholds

AIMS

The concept of proportionate/disproportionate functional mitral regurgitation (FMR) has been limited by the lack of a simple way to assess it and by the paucity of data showing its prognostic superiority. The aim of this study was to evaluate the prognostic value of an individualized method of assessing FMR proportionality.

METHODS AND RESULTS

We retrospectively identified 572 patients with at least mild FMR and reduced left ventricular ejection fraction (<50%) under medical therapy. To determine FMR proportionality status, we used an approach where a simple equation determined the individualized theoretical regurgitant volume (or effective regurgitant orifice area) threshold associated with haemodynamically significant FMR. Then, we compared the measured with the theoretical value to categorize the population into non-severe, proportionate, and disproportionate FMR. The primary endpoint was all-cause mortality. During a median follow-up of 3.8 years (interquartile range: 1.8-6.2), 254 patients died. The unadjusted mortality incidence per 100 persons-year rose as the degree of FMR disproportionality worsened. On multivariable analysis, disproportionate FMR remained independently associated with all-cause mortality [adjusted hazard ratio: 1.785; 95% confidence interval (CI): 1.249-2.550; P = 0.001]. The FMR proportionality concept showed greater discriminative power (C-statistic 0.639; 95% CI: 0.597-0.680) than the American (C-statistic 0.583; 95% CI: 0.546-0.621; P for comparison <0.001) and European guidelines (C-statistic 0.584; 95% CI: 0.547-0.620; P for comparison <0.001). When added to any of the before-mentioned guidelines, FMR proportionality also improved risk stratification by reclassifying patients into lower and higher risk subsets.

CONCLUSION

Disproportionate FMR is independently associated with all-cause mortality and improves the risk stratification of current guidelines.

Multimodality Imaging in Secondary Mitral Regurgitation

Secondary mitral regurgitation (sMR) is characterized by left ventricular (LV) dilatation or dysfunction, resulting in failure of mitral leaflet coaptation. sMR complicates up to 35% of ischaemic cardiomyopathies (1) and 57% of dilated cardiomyopathies (2). Due to the prevalence of coronary artery disease worldwide, ischaemic cardiomyopathy is the most frequently encountered cause of sMR in clinical practice. Although mortality from cardiovascular disease has gradually fallen in Western countries, severe sMR remains an independent predictor of mortality (3) and hospitalization for heart failure (4). The presence of even mild sMR following acute MI reduces long-term survival free of major adverse events (1). Such adverse outcomes worsen as the severity of sMR increases, due to a cycle in which LV remodeling begets sMR and vice versa. Current guidelines do not recommend invasive treatment of the sMR alone as a first-line approach, due to the paucity of evidence supporting improvement in clinical outcomes. Furthermore, a lack of international consensus on the thresholds that define severe sMR has resulted in confusion amongst clinicians determining whether intervention is warranted (5, 6). The recent Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation (COAPT) trial (7) assessing the effectiveness of transcatheter mitral valve repair is the first study to demonstrate mortality benefit from correction of sMR and has reignited interest in identifying patients who would benefit from mitral valve intervention. Multimodality imaging, including echocardiography and cardiovascular magnetic resonance (CMR), plays a key role in helping to diagnose, quantify, monitor, and risk stratify patients for surgical and transcatheter mitral valve interventions.