Mitral Valve Regurgitation in the Contemporary Era

Mitral regurgitation: lessons learned from COAPT and MITRA-Fr

Recent studies about percutaneous treatment of secondary mitral regurgitation (MR) underlined the importance of left ventricular geometry and features of mitral valve as determinants of procedural and long-term success. Guideline-directed medical therapy (GDMT), transcatheter mitral valve treatment (TMVT) and surgical procedures (mitral valve replacement, mitral valve repair at level of the annulus or subvalvular apparatus) have been extensively evaluated but not adequately compared in current clinical studies. A detailed analysis of the results of the study about transcatheter mitral valve repair would allow to evaluate the safety and effectiveness of such procedure and would provide potential indications for improving the quality of percutaneous and surgical repair in patients with moderate-to-severe secondary MR. Patients with proportionate MR (i.e., MR severity is proportional to the amount of left ventricular dilatation) are prone to respond to the optimization of medical therapy, while patients with disproportionate MR (i.e., MR severity is disproportionately higher than predicted by left ventricular dilatation, with high EROA and small left ventricle) are likely to benefit from additional repair. The identification of specific subpopulation of "high responders", based on the anatomic characteristics of the mitral valve and the relative dimensions of the annulus, the regurgitation and the left ventricle, can also apply to medical therapy. However, some pivotal component of MR (such as the symmetry of tethering and the differences in biomechanical features of leaflets) are not adequately investigated in current studies and warrant further evaluation.

Structural Heart Disease Emergencies

Structural heart disease (SHD) emergencies include acute deterioration of a stable lesion or development of a new critical lesion. Structural heart disease emergencies can produce heart failure and cardiogenic shock despite preserved systolic function that may not respond to standard medical therapy and typically necessitate surgical or percutaneous intervention. Comprehensive Doppler echocardiography is the initial diagnostic modality of choice to determine the cause and severity of the underlying SHD lesion. Patients with chronic SHD lesions which deteriorate due to intercurrent illness (eg, infection or arrhythmia) may not require urgent intervention, whereas patients with an acute SHD lesion often require definitive therapy. Medical stabilization prior to definitive intervention differs substantially between stenotic lesions (aortic stenosis, mitral stenosis, left ventricular outflow tract obstruction) and regurgitant lesions (aortic regurgitation, mitral regurgitation, ventricular septal defect). Patients with regurgitant lesions typically require aggressive afterload reduction and inotropic support, whereas patients with stenotic lesions may paradoxically require β-blockade and vasoconstrictors. Emergent cardiac surgery for patients with decompensated heart failure or cardiogenic shock carries a substantial mortality risk but may be necessary for patients who are not eligible for catheter-based percutaneous SHD intervention. This review explores initial medical stabilization and subsequent definitive therapy for patients with SHD emergencies.

Annuloplasty ring dehiscence after mitral valve repair: incidence, localization and reoperation

OBJECTIVES

Mitral valve (MV) annuloplasty ring dehiscence with subsequent recurrent mitral regurgitation represents an unusual but challenging clinical problem. Incidence, localization and outcomes for this complication have not been well defined.

METHODS

From 1996 to 2016, a total of 3478 patients underwent isolated MV repair with ring annuloplasty at the Leipzig Heart Centre. Of these patients, 57 (1.6%) underwent reoperation due to annuloplasty ring dehiscence. Echocardiographic data, operative and early postoperative characteristics as well as short- and long-term survival rates after MV reoperation were analysed.

RESULTS

Occurrences of ring dehiscence were acute (<30 days), early (≤1 year) and late (>1 year) in 44%, 33% and 23% of patients, respectively. Localization of annuloplasty ring dehiscence was found most frequently in the P3 segment (68%), followed by the P2 (51%) and the P1 segments (47%). The 30-day mortality rate and 1- and 5-year survival rates after MV reoperation were 2%, 89% and 74%, respectively. During reoperation, MV replacement was performed in 38 (67%) and MV re-repair in 19 (33%) patients.

CONCLUSIONS

Annuloplasty ring dehiscence is clinically less common, localized more frequently on the posterior annulus and occurs mostly acutely or early after MV repair. MV reoperation can be performed safely in such patients.

Characteristics and outcomes of patients with normal left atrial pressure undergoing transcatheter mitral valve repair

Objective

A subset of patients at the time of transcatheter mitral valve repair (TMVR) will have normal left atrial pressure (LAP) (<13 mm Hg) despite having severe mitral regurgitation (MR). The goal of this study was to determine clinical characteristics and outcomes in patients with normal LAP undergoing TMVR.

Methods

A single-centre retrospective cohort of consecutive patients who underwent transcatheter edge-to-edge mitral valve clip and continuous LAP monitoring between 5/1/2014 and 5/1/2018 was analysed. One-year mortality was compared by Kaplan–Meier survival curves. Multivariable analysis was performed to identify predictors of normal LAP and 1 year mortality.

Results

Of the 204 patients undergoing TMVR, 65% were men and the mean age was 81. Of these patients, 31 (15%) had normal LAP (mean LAP 10.5 mm Hg, mean V wave 16.5 mm Hg) and 173 had elevated LAP (mean LAP 19 mm Hg, mean V wave 32.5 mm Hg). The prevalence of severe MR was not different between groups, although the normal LAP group had significantly lower effective regurgitant orifice area and regurgitant volume. Other notable baseline characteristics including prior cardiac surgery, atrial fibrillation, hypertension, diabetes, congestive heart failure, body mass index, mechanism of MR and ejection fraction were similar between groups. However, there was an increased prevalence of chronic lung disease (CLD) (45.2% vs 17.3%, p<0.001) in the normal LAP group. On multivariate analysis, the only significant predictor of normal LAP was the presence of CLD (OR 4.79 (1.83–12.36), p=0.001) and 1-year mortality was significantly higher in the normal LAP group (32.3% vs 12.7%, p=0.006). After adjustment for comorbidities, normal LAP was no longer a predictor of 1-year mortality (RR 1.62 (0.64–4.06), p=0.32); however, CLD (RR 3.44 (1.37–8.67), p=0.01) remained a statistically significant predictor.

Conclusion

Normal LAP at the time of TMVR is associated with a higher incidence of CLD which independently predicts increased 1-year mortality. In patients with CLD and apparently severe MR, measurement of LAP may help identify those with lower likelihood of benefit from TMVR.

MRI Evaluation of an Atrial-Anchored Transcatheter Mitral Valve Replacement Implant

OBJECTIVE. A medical implant that is made from metal must undergo proper MRI testing to ensure patient safety. The purpose of this investigation was to assess issues with MRI with a newly developed atrial-anchored transcatheter mitral valve replacement (TMVR) implant. MATERIALS AND METHODS. The atrial-anchored TMVR implant underwent an in vitro evaluation for MRI safety issues using standardized techniques and well-accepted methods. Magnetic field interactions including translational attraction and torque and artifacts were tested at 3 T. MRI-related heating was assessed at 1.5 T/64 MHz and 3 T/128 MHz using numeric simulations with analytical modeling and experimental testing. RESULTS. The atrial-anchored TMVR implant exhibited minor magnetic field interactions (9° deflection angle and no torque) at 3 T. The findings from the numeric simulations with analytical modeling were used to guide the placement of the implant in the phantom for the heating test and to identify the position on the implant that would result in the highest temperature rise. The highest temperature elevations recorded for the TMVR implant obtained on MRI at 1.5 T/64 MHz and 3 T/128 MHz were 2.7°C and 2.4°C, respectively. The maximum artifact size seen on a gradient echo pulse sequence extended approximately 5 mm relative to the size of the implant. CONCLUSION. The results of the tests performed on the atrial-anchored TMVR implant revealed no substantial concerns with respect to the conditions used in this investigation. Therefore, a patient with this new implant can safely undergo MRI by following the specific conditions defined by this study. The implant was deemed MR Conditional.

Prognostic significance of moderate primary mitral regurgitation and concomitant paroxysmal atrial fibrillation

BACKGROUND

Severe primary mitral regurgitation [degenerative MR (DMR)] is associated with poor outcomes, including cardiac death and hospitalization due to worsening heart failure. However, little information is available regarding the characteristics of moderate DMR and their impacts on prognostic outcome. The aim of the present study was to investigate the prognosis and its determinants in patients with moderate DMR.

METHODS

We retroactively reviewed 13,700 consecutive patients who underwent transthoracic echocardiography and selected those with moderate DMR but without other underlying cardiac diseases. We assessed the characteristics and event-free rate of patients with moderate DMR compared with those of age- and gender-matched patients with mild or no MR.

RESULTS

The cohort included 182 (1%) patients with moderate DMR, and these were compared with 182 age- and gender-matched patients with mild or no MR. During the follow-up period of 1376 ± 652 days, 30 patients (8%) met the composite endpoint defined as cardiac death or hospitalization due to worsening heart failure. Kaplan-Meier analysis showed that patients with moderate DMR were significantly associated with a poor outcome compared to patients with mild or no MR (log-rank test p < 0.0001). Cox proportional hazard ratio revealed that moderate DMR and paroxysmal atrial fibrillation (PAF) were the independent predictors of the composite endpoint.

CONCLUSIONS

Patients with moderate DMR and concomitant PAF had a significantly worse outcome compared to those with mild or no MR. Active surveillance and some intervention for patients with PAF and moderate DMR may be required.

Echocardiographic prediction of surgical reparability in degenerative mitral regurgitation due to leaflet prolapse: a review

Introduction: Despite current guidelines provide recommendations for the optimal management of degenerative mitral regurgitation (MR), this condition remains often undertreated with delay in surgical referral and dismal effect on outcomes. Areas covered: This review focuses on the role of echocardiography in guiding mitral valve (MV) surgical repair in degenerative MR due to leaflet prolapse. Expert opinion: A stepwise protocol-driven echocardiography shared by referring physician and surgeon may help to guide referral to surgical repair in degenerative MR. This protocol particularly is useful to identify the ideal patho-anatomy for a successful and durable repair especially when early surgery is proposed and to refer the patient to centers of excellence in case of complex anatomy. Nearly 100% repair rate can be achieved when the surgical technique is adapted to the lesions seen in each valve. Three-dimensional echocardiography predicts repair complexity may be useful and should therefore be implemented. However, the current literature is far from comprehensive deriving from small, single-center studies. Therefore, reproducibility and external validation, especially with newly developed quantitative automated software, are still needed.

The Choice of Treatment in Ischemic Mitral Regurgitation With Reduced Left Ventricular Function

BACKGROUND

Ischemic mitral regurgitation is a condition characterized by mitral insufficiency secondary to an ischemic left ventricle. Primarily, the pathology is the result of perturbation of normal regional left ventricular geometry combined with adverse remodeling. We present a comprehensive review of contemporary surgical, medical, and percutaneous treatment options for ischemic mitral regurgitation, rigorously examined by current guidelines and literature.

METHODS

We conducted a literature search of the PubMed database, Embase, and the Cochrane Library (through November 2018) for studies reporting perioperative or late mortality and echocardiographic outcomes after surgical and nonsurgical intervention for ischemic mitral regurgitation.

RESULTS

Treatment of this condition is challenging and often requires a multimodality approach. These patients usually have multiple comorbidities that may preclude surgery as a viable option. A multidisciplinary team discussion is crucial in optimizing outcomes. There are several options for treatment and management of ischemic mitral regurgitation with differing benefits and risks. Guideline-directed medical therapy for heart failure is the treatment choice for moderate and severe ischemic mitral regurgitation, with consideration of coronary revascularization, mitral valve surgery, cardiac resynchronization therapy, or a combination of these, in appropriate candidates. The use of transcatheter mitral valve therapy is considered appropriate in high-risk patients with severe ischemic mitral regurgitation, heart failure, and reduced left ventricular ejection fraction, especially in those with hemodynamic instability.

CONCLUSIONS

The role of mitral valve surgery and transcatheter mitral valve therapy continues to evolve.

Novel approaches to the management of chronic systolic heart failure: future directions and unanswered questions

Despite improvements in outcomes in the last few decades for heart failure (HF) with reduced ejection fraction (HFrEF), there still remains a need for novel therapies as many patients incompletely recover with existing therapies and progress to advanced HF. In this review, we will discuss recent advances in the management of HFrEF with a focus on upcoming therapies that hold the greatest promise for clinical use. We will discuss novel pharmacological therapies and areas of uncertainty with existing therapies. We will also discuss the potential utility and controversy surrounding novel interventions for HF such as percutaneous mitral valve repair, atrial fibrillation ablation, and other emerging interventions with positive signals for benefit in HFrEF. Finally, we will summarize the current state of stem cell and gene therapy for HFrEF and future directions.

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Echocardiographic indices and severity of mitral regurgitation in dogs with preclinical degenerative mitral valve disease

Background

Describing severity of mitral regurgitation (MR) in dogs with degenerative mitral valve disease (DMVD) is challenging.

Hypothesis/Objectives

Mitral regurgitant fraction (RF), effective regurgitant orifice area (EROA), and the ratio of mitral regurgitant to aortic flow (Q_MR:Q_Ao) can be calculated from routine echocardiographic measurements and provide additional information regarding MR severity.

Animals

Fifty‐seven dogs with preclinical DMVD including 36 without and 21 with cardiomegaly.

Methods

Prospective observational study. The expected relationships among RF, EROA, and Q_MR:Q_Ao and 1‐dimensional measurements including left atrium to aortic root diameter ratio (LA:Ao) and normalized left ventricular internal dimension at end‐diastole (LVIDdN) were mathematically derived and calculated using echocardiographic data from the study population. Nonlinear goodness of fit was determined by calculation of the root mean standard error. The correlations between 1‐dimensional and multidimensional indices were analyzed using receiver operating characteristic curves.

Results

The relationships among RF, EROA, Q_MR:Q_Ao, and both LA:Ao and LVIDdN were curvilinear, and the multidimensional indices differentiated MR of variable severity. By contrast, 1‐dimensional measurements were insensitive to MR severity until RF equaled or exceeded 50%. Regurgitant fraction ≥50%, EROA to body surface area ≥0.347 and Q_MR:Q_Ao ≥0.79 were strongly associated with LA:Ao ≥1.6 and LVIDdN ≥1.7.

Conclusions and Clinical Importance

Regurgitant fraction, EROA, and Q_MR:Q_Ao quantify MR severity in dogs with preclinical DMVD in a manner that 1‐dimensional measurements do not.

Cardiac remodeling in aortic and mitral valve disease: a simulation study with clinical validation

Remodeling is an important long-term determinant of cardiac function throughout the progression of heart disease. Numerous biomolecular pathways for mechanosensing and transduction are involved. However, we hypothesize that biomechanical factors alone can explain changes in myocardial volume and chamber size in valve disease. A validated model of the human vasculature and the four cardiac chambers was used to simulate aortic stenosis, mitral regurgitation, and aortic regurgitation. Remodeling was simulated with adaptive feedback preserving myocardial fiber stress and wall shear stress in all four cardiac chambers. Briefly, the model used myocardial fiber stress to determine wall thickness and cardiac chamber wall shear stress to determine chamber volume. Aortic stenosis resulted in the development of concentric left ventricular hypertrophy. Aortic and mitral regurgitation resulted in eccentric remodeling and eccentric hypertrophy, with more pronounced hypertrophy for aortic regurgitation. Comparisons with published clinical data showed the same direction and similar magnitudes of changes in end-diastolic volume index and left ventricular diameters. Changes in myocardial wall volume and wall thickness were within a realistic range in both stenotic and regurgitant valvular disease. Simulations of remodeling in left-sided valvular disease support, in both a qualitative and quantitative manner, that left ventricular chamber size and hypertrophy are primarily determined by preservation of wall shear stress and myocardial fiber stress. NEW & NOTEWORTHY Cardiovascular simulations with adaptive feedback that normalizes wall shear stress and fiber stress in the cardiac chambers could predict, in a quantitative and qualitative manner, remodeling patterns seen in patients with left-sided valvular disease. This highlights how mechanical stress remains a fundamental aspect of cardiac remodeling. This in silico study validated with clinical data paves the way for future patient-specific predictions of remodeling in valvular disease.

Timing and mode of intervention for patients with left sided valvular heart disease: an individualized approach

Left sided valvular heart disease poses major impact on life and lifestyle. Medical therapy merely palliates chronic severe valve disease and once symptoms or haemodynamic sequelae appear, life expectancy is markedly truncated. In this article, we review the mechanisms of valve pathology, latest evidence in the quest for pharmacological options, means by which to predict deterioration, and standard and novel treatment options.