Use of Cardiac Magnetic Resonance Imaging in Assessing Mitral Regurgitation

Tricuspid valve flow measurement using a deep learning framework for automated valve-tracking 2D phase contrast

PURPOSE

Tricuspid valve flow velocities are challenging to measure with cardiovascular MR, as the rapidly moving valvular plane prohibits direct flow evaluation, but they are vitally important to diastolic function evaluation. We developed an automated valve-tracking 2D method for measuring flow through the dynamic tricuspid valve.

METHODS

Nine healthy subjects and 2 patients were imaged. The approach uses a previously trained deep learning network, TVnet, to automatically track the tricuspid valve plane from long-axis cine images. Subsequently, the tracking information is used to acquire 2D phase contrast (PC) with a dynamic (moving) acquisition plane that tracks the valve. Direct diastolic net flows evaluated from the dynamic PC sequence were compared with flows from 2D-PC scans acquired in a static slice localized at the end-systolic valve position, and also ventricular stroke volumes (SVs) using both planimetry and 2D PC of the great vessels.

RESULTS

The mean tricuspid valve systolic excursion was 17.8 ± 2.5 mm. The 2D valve-tracking PC net diastolic flow showed excellent correlation with SV by right-ventricle planimetry (bias ± 1.96 SD = -0.2 ± 10.4 mL, intraclass correlation coefficient [ICC] = 0.92) and aortic PC (-1.0 ± 13.8 mL, ICC = 0.87). In comparison, static tricuspid valve 2D PC also showed a strong correlation but had greater bias (p = 0.01) versus the right-ventricle SV (10.6 ± 16.1 mL, ICC = 0.61). In most (8 of 9) healthy subjects, trace regurgitation was measured at begin-systole. In one patient, valve-tracking PC displayed a high-velocity jet (380 cm/s) with maximal velocity agreeing with echocardiography.

CONCLUSION

Automated valve-tracking 2D PC is a feasible route toward evaluation of tricuspid regurgitant velocities, potentially solving a major clinical challenge.

New atrio-ventricular indices derived from conventional cine MRI correlate with functional capacity in patients with asymptomatic primary mitral regurgitation

Mitral regurgitation (MR) is associated with morphological and functional alterations of left atrium (LA) and ventricle (LV), possibly inducing LA-LV misalignment. We aimed to: (1) characterize angulation between LA and mitral annulus from conventional cine MRI data and feature-tracking (FT) contours, (2) assess their associations with functional capacity in MR patients, as assessed by oxygen consumption (peak-VO2) and minute ventilation to carbon dioxide production (VE/VCO2) slope, in comparison with MRI LA/LV strain indices. Thirty-two asymptomatic primary MR patients (56 [40; 66] years, 12 women) underwent cardiac MRI resulting in LA/LV conventional FT-derived strain indices. Then, end-diastolic angles were derived from FT LA contours: (1) α, centered on the LA centre of mass and defined by mitral valve extremities, (2) γ, centered on the mitral ring anterior/lateral side, and defined by LA centre and the other extremity of the mitral ring. Cardiopulmonary exercise testing with simultaneous echocardiography were also performed; peak-VO2 and VE/VCO2 slope were measured. While peak-VO2 and VE/VCO2 slope were not correlated to LA/LV strains, they were significantly associated with angles (α: r = 0.50, p = 0.003 and r = - 0.52, p = 0.003; γ: r = - 0.53, p = 0.002 and r = 0.52, p = 0.003; respectively), independently of age and gender (R2 ≥ 0.29, p ≤ 0.03). In primary MR, the new LA/mitral annulus angles, computed directly from standard-of-care MRI, are better correlated to exercise tolerance than conventional LA/LV strain.

Cardiac magnetic resonance imaging in the evaluation and management of mitral valve prolapse - a comprehensive review

Mitral valve prolapse is a common valve disorder that usually has a benign prognosis unless there is significant regurgitation or LV impairment. However, a subset of patients are at an increased risk of ventricular arrhythmias and sudden cardiac death, which has led to the recognition of "arrhythmic mitral valve prolapse" as a clinical entity. Emerging risk factors include mitral annular disjunction and myocardial fibrosis. While echocardiography remains the primary method of evaluation, cardiac magnetic resonance has become crucial in managing this condition. Cine magnetic resonance sequences provide accurate characterization of prolapse and annular disjunction, assessment of ventricular volumes and function, identification of early dysfunction and remodeling, and quantitative assessment of mitral regurgitation when integrated with flow imaging. However, the unique strength of magnetic resonance lies in its ability to identify tissue changes. T1 mapping sequences identify diffuse fibrosis, in turn related to early ventricular dysfunction and remodeling. Late gadolinium enhancement sequences detect replacement fibrosis, an independent risk factor for ventricular arrhythmias and sudden cardiac death. There are consensus documents and reviews on the use of cardiac magnetic resonance specifically in arrhythmic mitral valve prolapse. However, in this article, we propose an algorithm for the broader use of cardiac magnetic resonance in managing this condition in various scenarios. Future advancements may involve implementing techniques for tissue characterization and flow analysis, such as 4D flow imaging, to identify patients with ventricular dysfunction and remodeling, increased arrhythmic risk, and more accurate grading of mitral regurgitation, ultimately benefiting patient selection for surgical therapy.

Estimate of the hydraulic force in the aging heart: a cardiovascular magnetic resonance imaging study

BACKGROUND

Coupling between left ventricle (LV) and left atrium (LA) plays a central role in the process of cardiac remodeling during aging and development of cardiac disease. The hydraulic force (HyF) is related to variation in size between LV and LA. The objectives of this study were to: (1) derive an estimate of left atrioventricular HyF using cine- Magnetic Resonance Imaging (MRI) in healthy subjects with a wide age range, and (2) study its relationship with age and conventional diastolic function parameters, as estimated by reference echocardiography.

METHODS

We studied 119 healthy volunteers (mean age 44 ± 17 years, 58 women) who underwent Doppler echocardiography and MRI on the same day. Conventional transmitral flow early (E) and late (A) LV filling peak velocities as well as mitral annulus diastolic longitudinal peak velocity (E') were derived from echocardiography. MRI cine SSFP images in longitudinal two and four chamber views were acquired, and analyzed using feature tracking (FT) software. In addition to conventional LV and LA strain measurements, FT-derived LV and LA contours were further used to calculate chamber cross-sectional areas. HyF was approximated as the difference between the LV and LA maximal cross-sectional areas in the diastasis phase corresponding to the lowest LV-LA pressure gradient. Univariate and multivariate analyses while adjusting for appropriate variables were used to study the associations between HyF and age as well as diastolic function and strain indices.

RESULTS

HyF decreased significantly with age (R²=0.34, p < 0.0001). In addition, HyF was significantly associated with conventional indices of diastolic function and LA strain: E/A: R²=0.24, p < 0.0001; E': R²=0.24, p < 0.0001; E/E': R²=0.12, p = 0.0004; LA conduit longitudinal strain: R²=0.27, p < 0.0001. In multivariate analysis, associations with E/A (R2 = 0.39, p = 0.03) and LA conduit strain (R2 = 0.37, p = 0.02) remained significant after adjustment for age, sex, and body mass index.

CONCLUSIONS

HyF, estimated using FT contours, which are primarily used to quantify LV/LA strain on standard cardiac cine MRI, varied significantly with age in association with subclinical changes in ventricular filling. Its usefulness in cohorts of patients with left heart disease to detect LV-LA uncoupling remains to be evaluated.

Mitral annulus disjunction in consecutive patients undergoing cardiovascular magnetic resonance: Where is the boundary between normality and disease?

BACKGROUND

The presence of mitral annulus disjunction (MAD) has been considered a high-risk feature for sudden cardiac death based on selected study populations. We aimed to assess the prevalence of MAD in consecutive patients undergoing clinically indicated cardiovascular magnetic resonance (CMR), its association with ventricular arrhythmias, mitral valve prolapse (MVP), and other CMR features.

METHODS

This single-center retrospective study included consecutive patients referred to CMR at our institution between June 2021 and November 2021. MAD was defined as a ≥1 mm displacement between the left atrial wall-mitral valve leaflet junction and the left ventricular wall during end-systole. MAD extent was defined as the maximum longitudinal displacement. Associates of MAD were evaluated at univariable and multivariable regression analysis. The study endpoint, a composite of (aborted) sudden cardiac death, unexplained syncope, and sustained ventricular tachycardia, was evaluated at a 12-month follow-up.

RESULTS

Four hundred and forty-one patients 55 ± 18 years, 267/441 (61%) males) were included, and 29/441 (7%) had MVP. The prevalence of MAD ≥1 mm, 4 mm, and 6 mm was 214/441 (49%), 63/441 (14%), and 15/441 (3%), respectively. Patients with MVP showed a higher prevalence of MAD greater than 1 mm (26/29 (90%) vs 118/412 (46%)); p < 0.001), 4 mm (14/29 (48%) vs 49/412 (12%)); p < 0.001), and 6 mm (3/29 (10%) vs 12/412 (3%)); p = 0.03), and a greater MAD extent (4.2 mm, 3.0-5.7 mm vs 2.8 mm, 1.9-4.0 mm; p < 0.001) compared to patients without MVP. MVP was the only morpho-functional abnormality associated with MAD at multivariable analysis (p < 0.001). A high burden of ventricular ectopic beats at baseline Holter-electrocardiogram was associated with MAD ≥4 mm and MAD extent (p < 0.05). The presence of MAD ≥1 mm (0.9% vs 1.8%; p = 0.46), MAD ≥4 mm (1.6% vs 1.3%; p = 0.87), or MVP (3.5% vs 1.2%; p = 0.32) were not associated with the study endpoint, whereas patients with MAD ≥6 mm showed a trend toward a higher likelihood of the study endpoint (6.7% vs 1.2%; p = 0.07).

CONCLUSION

MAD of limited severity was common in consecutive patients undergoing CMR. Patients with MVP showed higher prevalence and greater extent of MAD. Extended MAD was rarer and showed association with ventricular arrhythmias at baseline. The mid-term prognosis of MAD seems benign; however, prospective studies are warranted to search for potential "malignant MAD extents" to improve patients' risk stratification.

Tricuspid regurgitation in pulmonary arterial hypertension: a right ventricular volumetric and functional analysis

BACKGROUND

The consequences of tricuspid regurgitation (TR) for right ventricular (RV) function and prognosis in pulmonary arterial hypertension (PAH) are poorly described and effects of tricuspid valve repair on the RV are difficult to predict.

METHODS

In 92 PAH patients with available cardiac magnetic resonance (CMR) studies, TR volume was calculated as the difference between RV stroke volume and forward stroke volume, i.e. pulmonary artery (PA) stroke volume. Survival was estimated from the time of the CMR scan to cardiopulmonary death or lung transplantation. In a subgroup, pressure-volume loop analysis including two-parallel elastances was applied to evaluate effective elastances, including net afterload (effective arterial elastance (E a)), forward afterload (effective pulmonary arterial elastance (E pa)) and backward afterload (effective tricuspid regurgitant elastance (E TR)). The effects of tricuspid valve repair were simulated using the online software package Harvi.

RESULTS

26% of PAH patients had a TR volume ≥30 mL. Greater TR volume was associated with increased N-terminal pro-brain natriuretic peptide (p=0.018), mean right atrial pressure (p<0.001) and RV end-systolic and -diastolic volume (both p<0.001). TR volume ≥30 mL was associated with a poor event-free survival (p=0.008). In comparison to E a, E pa correlated better with indices of RV dysfunction. Lower end-systolic elastance (E es) (p=0.002) and E TR (p=0.030), higher E pa (p=0.001) and reduced E es/E pa (p<0.001) were found in patients with a greater TR volume. Simulations predicted that tricuspid valve repair increases RV myocardial oxygen consumption in PAH patients with severe TR and low E es unless aggressive volume reduction is accomplished.

CONCLUSIONS

In PAH, TR has prognostic significance and is associated with low RV contractility and RV-PA uncoupling. However, haemodynamic simulations showed detrimental consequences of tricuspid valve repair in PAH patients with low RV contractility.

Multi-parametric assessment of cardiac magnetic resonance images to distinguish myocardial infarctions: A tensor-based radiomics feature

AIM

This study assessed the myocardial infarction (MI) using a novel fusion approach (multi-flavored or tensor-based) of multi-parametric cardiac magnetic resonance imaging (CMRI) at four sequences; T1-weighted (T1W) in the axial plane, sense-balanced turbo field echo (sBTFE) in the axial plane, late gadolinium enhancement of heart short axis (LGE-SA) in the sagittal plane, and four-chamber views of LGE (LGE-4CH) in the axial plane.

METHODS

After considering the inclusion and exclusion criteria, 115 patients (83 with MI diagnosis and 32 as healthy control patients), were included in the present study. Radiomic features were extracted from the whole left ventricular myocardium (LVM). Feature selection methods were Least Absolute Shrinkage and Selection Operator (Lasso), Minimum Redundancy Maximum Relevance (MRMR), Chi-Square (Chi2), Analysis of Variance (Anova), Recursive Feature Elimination (RFE), and SelectPersentile. The classification methods were Support Vector Machine (SVM), Logistic Regression (LR), and Random Forest (RF). Different metrics, including receiver operating characteristic curve (AUC), accuracy, F1- score, precision, sensitivity, and specificity were calculated for radiomic features extracted from CMR images using stratified five-fold cross-validation.

RESULTS

For the MI detection, Lasso (as the feature selection) and RF/LR (as the classifiers) in sBTFE sequences had the best performance (AUC: 0.97). All features and classifiers of T1 + sBTFE sequences with the weighted method (as the fused image), had a good performance (AUC: 0.97). In addition, the results of the evaluated metrics, especially mean AUC and accuracy for all models, determined that the T1 + sBTFE-weighted fused method had strong predictive performance (AUC: 0.93±0.05; accuracy: 0.93±0.04), followed by T1 + sBTFE-PCA fused method (AUC: 0.85±0.06; accuracy: 0.84±0.06).

CONCLUSION

Our selected CMRI sequences demonstrated that radiomics analysis enables to detection of MI accurately. Among the investigated sequences, the T1 + sBTFE-weighted fused method with the highest AUC and accuracy values was chosen as the best technique for MI detection.

Mitral Regurgitation: Advanced Imaging Parameters and Changing Treatment Landscape

Mitral regurgitation is a common valvular heart disease with increasing prevalence due to the aging population. In degenerative (primary) mitral regurgitation, medical therapies are limited and the mainstay of treatment is mitral valve surgery. Patients are referred for mitral valve surgery based on the American College of Cardiology/American Heart Association guidelines, which recommend surgery in patients with severe mitral regurgitation. Echocardiography uses multiple parameters that lack reproducibility and accuracy. Studies comparing cardiovascular magnetic resonance (CMR) and echocardiography have shown that CMR is a better predictor of clinical outcome and postsurgical left ventricular remodeling than echocardiography.

Valid and Reproducible Quantitative Assessment of Cardiac Volumes by Echocardiography in Patients with Valvular Heart Diseases-Possible or Wishful Thinking?

The analysis of left ventricular function is predominantly based on left ventricular volume assessment. Especially in valvular heart diseases, the quantitative assessment of total and effective stroke volumes as well as regurgitant volumes is necessary for a quantitative approach to determine regurgitant volumes and regurgitant fraction. In the literature, there is an ongoing discussion about differences between cardiac volumes estimated by echocardiography and cardiac magnetic resonance tomography. This viewpoint focuses on the feasibility to assess comparable cardiac volumes with both modalities. The former underestimation of cardiac volumes determined by 2D and 3D echocardiography is presumably explained by methodological and technical limitations. Thus, this viewpoint aims to stimulate an urgent and critical rethinking of the echocardiographic assessment of patients with valvular heart diseases, especially valvular regurgitations, because the actual integrative approach might be too error prone to be continued in this form. It should be replaced or supplemented by a definitive quantitative approach. Valid quantitative assessment by echocardiography is feasible once echocardiography and data analysis are performed with methodological and technical considerations in mind. Unfortunately, implementation of this approach cannot generally be considered for real-world conditions.

Echocardiography vs. CMR in the Quantification of Chronic Mitral Regurgitation: A Happy Marriage or Stormy Divorce?

Quantification of chronic mitral regurgitation (MR) is essential to guide patients’ clinical management and define the need and appropriate timing for mitral valve surgery. Echocardiography represents the first-line imaging modality to assess MR and requires an integrative approach based on qualitative, semiquantitative, and quantitative parameters. Of note, quantitative parameters, such as the echocardiographic effective regurgitant orifice area, regurgitant volume (RegV), and regurgitant fraction (RegF), are considered the most reliable indicators of MR severity. In contrast, cardiac magnetic resonance (CMR) has demonstrated high accuracy and good reproducibility in quantifying MR, especially in cases with secondary MR; nonholosystolic, eccentric, and multiple jets; or noncircular regurgitant orifices, where quantification with echocardiography is an issue. No gold standard for MR quantification by noninvasive cardiac imaging has been defined so far. Only a moderate agreement has been shown between echocardiography, either with transthoracic or transesophageal approaches, and CMR in MR quantification, as supported by numerous comparative studies. A higher agreement is evidenced when echocardiographic 3D techniques are used. CMR is superior to echocardiography in the calculation of the RegV, RegF, and ventricular volumes and can provide myocardial tissue characterization. However, echocardiography remains fundamental in the pre-operative anatomical evaluation of the mitral valve and of the subvalvular apparatus. The aim of this review is to explore the accuracy of MR quantification provided by echocardiography and CMR in a head-to-head comparison between the two techniques, with insight into the technical aspects of each imaging modality.

Multimodality Imaging in Valvular Structural Interventions

Structural valvular interventions have skyrocketed in the past decade with new devices becoming available and indications for patients who would previously have been deemed inoperable. Furthermore, while echocardiography is the main imaging tool and the first line for patient screening, cardiac magnetic resonance and CT are now essential tools in pre-planning and post-procedural follow-up. This review aims to address imaging modalities and their scope in aortic, mitral and tricuspid structural valvular interventions, including multimodality imaging. Pulmonary valve procedures, which are mostly carried out in patients with congenital problems, are discussed. This article presents a guide on individualised imaging approcahes on each of the available interventional procedures.

The Role of Cardiovascular Magnetic Resonance in Patients with Mitral Regurgitation

The 2019 Global Burden of Disease (GBD) study estimated that there were approximately 24.2 million people affected worldwide by degenerative mitral regurgitation (MR), resulting in 34,200 deaths. After aortic stenosis, MR is the most prevalent VHD in Europe and the second-most common VHD to pose indications for surgery in western countries. Current ESC and AHA/ACC guidelines for the management of VHD emphasize the importance of an integrative approach for the assessment of MR severity, which is of paramount importance in dictating the timing for surgery. Transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) are the first-line imaging modalities; however, despite the technological advancement, sometimes, the final diagnosis on the degree of the disease may still be challenging. In the last 20 years, CMR has emerged as a robust technique in the assessment of patients with cardiac disease, and, recently, its role is gaining more and more importance in the field of VHD. In fact, CMR is the gold standard in the assessment of cardiac volumes, and it is possible to accurately evaluate the regurgitant volume. The purpose of this review is to outline the current state-of-the-art management of MR by using Cardiac Magnetic Resonance (CMR).

Multimodality imaging for the management of patients with primary mitral regurgitation

Advanced cardiac imaging (ACI), including myocardial deformation imaging, 3D echocardiography and cardiac magnetic resonance, overcomes the limitations of conventional echocardiography in the assessment of patients with primary mitral regurgitation (MR). They enable a more precise MR quantification and reveal early changes before advanced and irreversible remodeling with depressed heart function occurs. ACI permits a thorough analysis of mitral valvular anatomy and MR mechanisms (important for planning and guiding percutaneous and surgical procedures) and helps to identify structural and functional changes coupled with a high arrhythmogenic potential, especially the occurrence of atrial fibrillation and heart failure development. The key question is how the data provided by ACI can improve the current management of primary MR.

Rationale and clinical applications of 4D flow cardiovascular magnetic resonance in assessment of valvular heart disease: a comprehensive review

BACKGROUND

Accurate evaluation of valvular pathology is crucial in the timing of surgical intervention. Whilst transthoracic echocardiography is widely available and routinely used in the assessment of valvular heart disease, it is bound by several limitations. Although cardiovascular magnetic resonance (CMR) imaging can overcome many of the challenges encountered by echocardiography, it also has a number of limitations.

MAIN TEXT

4D Flow CMR is a novel technique, which allows time-resolved, 3-dimensional imaging. It enables visualisation and direct quantification of flow and peak velocities of all valves simultaneously in one simple acquisition, without any geometric assumptions. It also has the unique ability to measure advanced haemodynamic parameters such as turbulent kinetic energy, viscous energy loss rate and wall shear stress, which may add further diagnostic and prognostic information. Although 4D Flow CMR acquisition can take 5-10 min, emerging acceleration techniques can significantly reduce scan times, making 4D Flow CMR applicable in contemporary clinical practice.

CONCLUSION

4D Flow CMR is an emerging CMR technique, which has the potential to become the new reference-standard method for the evaluation of valvular lesions. In this review, we describe the clinical applications, advantages and disadvantages of 4D Flow CMR in the assessment of valvular heart disease.

Role of Cardiovascular Magnetic Resonance in Native Valvular Regurgitation: A Comprehensive Review of Protocols, Grading of Severity, and Prediction of Valve Surgery

Valvular regurgitation is common in developed countries with an increasing prevalence due to the aging of the population and more accurate diagnostic imaging methods. Echocardiography is the gold standard method for the assessment of the severity of valvular heart regurgitation. Nonetheless, cardiovascular magnetic resonance (CMR) has emerged as an additional tool for assessing mainly the severity of aortic and mitral valve regurgitation in the setting of indeterminate findings by echocardiography. Moreover, CMR is a valuable imaging modality to assess ventricular volume and flow, which are useful in the calculation of regurgitant volume and regurgitant fraction of mitral valve regurgitation, aortic valve regurgitation, tricuspid valve regurgitation, and pulmonary valve regurgitation. Notwithstanding this, reference values and optimal thresholds to determine the severity and prognosis of valvular heart regurgitation have been studied lesser by CMR than by echocardiography. Hence, further larger studies are warranted to validate the potential prognostic relevance of the severity of valvular heart regurgitation determined by CMR. The present review describes, analyzes, and discusses the use of CMR to determine the severity of valvular heart regurgitation in clinical practice.

Society for Cardiovascular Magnetic Resonance 2021 cases of SCMR and COVID-19 case collection series

The Society for Cardiovascular Magnetic Resonance (SCMR) is an international society focused on the research, education, and clinical application of cardiovascular magnetic resonance (CMR). "Cases of SCMR" is a case series hosted on the SCMR website ( https://www.scmr.org ) that demonstrates the utility and importance of CMR in the clinical diagnosis and management of cardiovascular disease. The COVID-19 Case Collection highlights the impact of coronavirus disease 2019 (COVID-19) on the heart as demonstrated on CMR. Each case in series consists of the clinical presentation and the role of CMR in diagnosis and guiding clinical management. The cases are all instructive and helpful in the approach to patient management. We present a digital archive of the 2021 Cases of SCMR and the 2020 and 2021 COVID-19 Case Collection series of nine cases as a means of further enhancing the education of those interested in CMR and as a means of more readily identifying these cases using a PubMed or similar literature search engine.

Grading mitral regurgitation using 4D flow CMR: Comparison to transthoracic echocardiography

OBJECTIVES

To determine the 4D Flow Cardiac Magnetic Resonance (CMR) thresholds that achieve the best agreement with transthoracic echocardiography (TTE) for grading mitral regurgitation (MR).

METHODS

We conducted a single-center prospective study of patients evaluated for chronic primary MR in 2016-2020. MR was evaluated blindly by TTE and 4D Flow CMR, respectively by two cardiologists and two radiologists with decades of experience. MR was graded with both methods as mild, moderate, or severe. 4D Flow CMR measurements included MR regurgitant volume per beat (RV) and mitral anterograde flow per beat (MF). RF was obtained as the ratio RV/MF. Additionally, MF was compared to left ventricular stroke volume (LVSV) by cine-CMR.

RESULTS

We included 33 patients in the initial cohort and 33 in the validation cohort. Inter-observer agreement was excellent for 4D Flow CMR ICC = .94 (95% CI, .86-.97, p < 0.0001). Using recommended TTE thresholds (30 ml, 60 ml, 30%, 50%), agreement was moderate for RV and RF. The best agreement between 4D Flow CMR and TTE was obtained with CMR thresholds of 20 and 40 ml for RV (κ = .93; 95% CI, .8-1) and 20% and 37% for RF (κ = .90; 95% CI, .7-.9). In the validation cohort, agreement between TTE and 4D Flow CMR was good with the optimal thresholds (κ = .78; 95% CI, .61-.94).

CONCLUSION

We propose CMR thresholds that provide a good agreement between TTE and CMR for grading MR. Further studies are needed to fully validate 4D-Flow CMR accuracy for primary MR quantification.

American Society of Echocardiography Algorithm for Degenerative Mitral Regurgitation: Comparison With CMR

OBJECTIVES

The purpose of this study was to compare the American Society of Echocardiography (ASE) algorithm for assessing mitral regurgitation (MR) to cardiac magnetic resonance (CMR) and left ventricular (LV) remodeling following mitral intervention.

BACKGROUND

The ASE recommends integrating multiple echocardiographic parameters for assessing MR. The ASE guidelines include an algorithm that weighs the parameters and highlights those considered indicative of definitely mild or definitely severe MR.

METHODS

We prospectively enrolled 152 (age 62 ± 13 years; 59% male) patients with degenerative MR who underwent ASE algorithm-guided echocardiographic and CMR grading of MR severity. Using the ASE algorithm, patients were graded as definitely mild, grade I, grade II, grade III, grade IV, or definitely severe MR. CMR MR volume was graded as mild (<30 mL), grade II moderate (30-44 mL), grade III moderate (45-59 mL), or severe (≥60 mL). A subgroup of 63 patients underwent successful mitral intervention, of whom 48 had postintervention CMR.

RESULTS

Only 52% of patients with definitely severe MR by the ASE algorithm had severe MR by CMR, and 10% had mild MR by CMR. There was an increase in post mitral intervention LV reverse remodeling with worsening MR severity using CMR (P < 0.0001) but not the ASE algorithm (P = 0.07). Severe MR by CMR was an independent predictor of post mitral intervention LV reverse remodeling and definitely severe MR by the ASE algorithm was not.

CONCLUSIONS

In patients with degenerative MR, agreement between CMR and the ASE algorithm was suboptimal. Severe MR by CMR was an independent predictor of post mitral intervention LV reverse remodeling, whereas definitely severe MR by the ASE algorithm was not. These findings suggest an important role for CMR in surgical decision making in degenerative MR. (Comparison Study of Echocardiography and Cardiovascular Magnetic Resonance Imaging in the Assessment of Mitral and Aortic Regurgitation; NCT04038879).

Left Ventricular Remodeling in Non-syndromic Mitral Valve Prolapse: Volume Overload or Concomitant Cardiomyopathy?

Mitral valve prolapse (MVP) is a common valvular disorder that can be associated with mitral regurgitation (MR), heart failure, ventricular arrhythmias and sudden cardiac death. Given the prognostic impact of these conditions, it is important to evaluate not only mitral valve morphology and regurgitation, but also the presence of left ventricular (LV) function and remodeling. To date, several possible hypotheses have been proposed regarding the underlying mechanisms of LV remodeling in the context of non-syndromic MVP, but the exact pathophysiological explanation remains elusive. Overall, volume overload related to severe MR is considered the main cause of LV dilatation in MVP. However, significant LV remodeling has been observed in patients with MVP and no/mild MR, particularly in patients with bileaflet MVP or Barlow's disease, generating several new hypotheses. Recently, the concept of "prolapse volume" was introduced, adding a significant volume load to the LV on top of the transvalvular MR volume. Another possible hypothesis is the existence of a concomitant cardiomyopathy, supported by the link between MVP and myocardial fibrosis. The origin of this cardiomyopathy could be either genetic, a second hit (e.g., on top of genetic predisposition) and/or frequent ventricular ectopic beats. This review provides an overview of the different mechanisms and remaining questions regarding LV remodeling in non-syndromic MVP. Since technical specifications of imaging modalities impact the evaluation of MR severity and LV remodeling, and therefore might influence clinical decision making in these patients, this review will also discuss assessment of MVP using different imaging modalities.

Impact of different degrees of left ventricular strain on left atrial mechanics in heart failure with preserved ejection fraction

Background

Impairment of left atrial (LA) function is linked to left ventricle (LV) mechanics in patients with heart failure with preserved ejection fraction (HFpEF). In this study, we set forth to determine the difference in LA mechanics compared between HFpEF patients with different degrees of LV strains using the cardiac magnetic resonance feature tracking technique.

Methods

This retrospective study enrolled 79 patients with prior heart failure event and LV ejection fraction (LVEF) ≥ 50% (HFpEF group) together with 2:1 matched controls. LV global longitudinal strain (GLS), global circumferential strain (GCS), and global radial strain (GRS); LA emptying fraction (LAEF); and, LA strains consisting of reservoir phase strain (LAS_r), conduit phase strain (LAS_cd), and contraction phase strain (LAS_ct) were derived from cine images. All LA parameters were compared between HFpEF subgroups (lower and higher LV strain stratified by the median of each LV strain value) and controls.

Results

A total of 237 subjects were included. HFpEF had a lower LAEF and LA strain values compared with controls. The mean GLS value was significantly different between HFpEF and controls (− 13.3 ± 3.4% vs. − 15.4 ± 2.2%, p < 0.001). HFpEF with lower GLS (value ≥  − 13.1%) had significantly impaired LA mechanical parameters compared with both HFpEF with higher GLS and controls independent of potential confounders, as follows: LAEF (38.8 ± 16.6% vs. 48.6 ± 15.7% and 54.2 ± 12.2%), LAS_r (14.6 ± 7.1% vs. 24.3 ± 9.6% and 26.7 ± 8.8%), and LAS_cd (− 6.6 ± 3.9% vs. − 12.9 ± 6.0% and − 14.7 ± 7.4%) (post hoc analysis of variance p < 0.05 for all comparisons). Similarly, HFpEF with lower GCS (value ≥  − 16.6%) or lower GRS (value < 27.9%) also had significant impairment of LAS_r and LAS_cd compared with the higher strain group and controls. Abnormal LAEF (< 50%) and abnormal LAS_r (< 23%) are independently associated with NYHA class ≥ II (Odds ratio [OR] 3.894 [95% CI 2.202–6.885] p < 0.001, adjusted OR 3.382 [1.791–6.389] p < 0.001 for abnormal LAEF; and OR 2.613 [1.497–4.562] p = 0.001, adjusted OR 2.064 [1.118–2.110] p = 0.021 for abnormal LAS_r).

Conclusions

Patients with HFpEF were found to have impaired LV and LA mechanics. Abnormal LA mechanics was highly prevalent in HFpEF patients with lower LV strain and significantly associated with the symptomatic status of the patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02608-7.

Percutaneous Edge-to-Edge Mitral Valve Repair for Functional Mitral Regurgitation

The presence and severity of functional mitral regurgitation (FMR) is associated with worse outcomes in patients with heart failure and reduced ejection fraction. Prior to the availability of percutaneous mitral valve repair, management for FMR has been limited to medical therapy, cardiac resynchronization therapy for a specific subset of patients and surgery which has yet to demonstrate mortality benefits. Transcatheter edge-to-edge repair (TEER) of the mitral valve has emerged in the past decade as an invaluable member of the armamentarium against FMR with the 2 landmark randomized controlled trials providing deep insights on patient selection. In addition, TEER has spurred the rapid advancement in our understanding of FMR. This article seeks to provide an overview as well as our current understanding on the role of TEER in FMR.

Garden-Hose Mitral Regurgitation: A Variant That Can Result in Underestimation of Severity: A Multimodality Imaging Case Study

The quantitative assessment of mitral regurgitation (MR) by echocardiography has limitations. Cardiac magnetic resonance (CMR) imaging has an emerging role in the quantitation of MR, and preliminary studies indicate that CMR assessment may more accurately quantify MR and better correlate with postsurgical left ventricular reverse remodeling. The authors here report a case of MR in which multimodality imaging with CMR and transesophageal echocardiography was crucial in accurately diagnosing the severity of MR when transthoracic and provocative supine bike echocardiography underestimated the degree of MR in a unique variant known as "garden-hose" MR.

30-minute CMR for common clinical indications: a Society for Cardiovascular Magnetic Resonance white paper

BACKGROUND

Despite decades of accruing evidence supporting the clinical utility of cardiovascular magnetic resonance (CMR), adoption of CMR in routine cardiovascular practice remains limited in many regions of the world. Persistent use of long scan times of 60 min or more contributes to limited adoption, though techniques available on most scanners afford routine CMR examination within 30 min. Incorporating such techniques into standardize protocols can answer common clinical questions in daily practice, including those related to heart failure, cardiomyopathy, ventricular arrhythmia, ischemic heart disease, and non-ischemic myocardial injury. BODY: In this white paper, we describe CMR protocols of 30 min or shorter duration with routine techniques with or without stress perfusion, plus specific approaches in patient and scanner room preparation for efficiency. Minimum requirements for the scanner gradient system, coil hardware and pulse sequences are detailed. Recent advances such as quantitative myocardial mapping and other add-on acquisitions can be incorporated into the proposed protocols without significant extension of scan duration for most patients.

CONCLUSION

Common questions in clinical cardiovascular practice can be answered in routine CMR protocols under 30 min; their incorporation warrants consideration to facilitate increased access to CMR worldwide.

Valvular Cardiomyopathy: The Value of Cardiovascular Magnetic Resonance Imaging

Cardiovascular magnetic resonance (CMR) imaging has had a vast impact on the understanding of a wide range of disease processes and pathophysiological mechanisms. More recently, it has contributed significantly to the diagnosis and risk stratification of patients with valvular heart disease. With its increasing use, CMR allows for a detailed, reproducible, qualitative, and quantitative evaluation of left ventricular volumes and mass, thereby enabling assessment of the haemodynamic impact of a valvular lesion upon the myocardium. Postprocessing of the routinely acquired images with feature tracking CMR methodology can give invaluable information about myocardial deformation and strain parameters that suggest subclinical ventricular impairment that remains undetected by conventional measures such as the ejection fraction (EF). T1 mapping and late gadolinium enhancement (LGE) imaging provide deep myocardial tissue characterisation that is changing the approach towards risk stratification of patients as an increasing body of evidence suggests that the presence of fibrosis is related to adverse events and prognosis. This review summarises the current evidence regarding the utility of CMR in the left ventricular assessment of patients with aortic stenosis or mitral regurgitation and its value in diagnosis, risk stratification, and management.

Loss of left ventricular rotation is a significant determinant of functional mitral regurgitation

AIM

To evaluate insufficient rotational movement of the left ventricle (LV) as a potential novel mechanism for functional regurgitation of the mitral valve (FMR).

METHODS AND RESULTS

We compared reference subjects and patients with LV dysfunction (LVD, ejection fraction EF < 50%) with and without FMR (regurgitant volume RVol>10 ml). Subjects without structural mitral valve pathology undergoing cardiac MRI were evaluated. Delayed enhancement, global LV remodeling parameters, systolic twist and torsion were measured (using manual and novel automated cardiac MRI tissue-tracking). The study included 117 subjects with mean ± SD age 50.4 ± 17.8 years, of which 30.8% were female. Compared to subjects with LVD without FMR (n = 31), those with FMR (n = 37) had similar clinical characteristics, diagnoses, delayed enhancement, EF, and longitudinal strain. Subjects with FMR had significantly larger left ventricles (EDVi:136.6 ± 41.8 vs 97.5 ± 26.2 ml/m, p < 0.0001) with wider separation between papillary muscles (21.1 ± 7.6 vs 17.2 ± 5.7 mm, p = 0.023). Notably, they had lower apical (p < 0.0001) but not basal rotation and lower peak systolic twist (3.1 ± 2.4° vs 5.5 ± 2.5°, p < 0.0001) and torsion (0.56 ± 0.38°/cm vs 0.88 ± 0.52°/cm, p = 0.004). In a multivariate model for RVol including age, gender, twist, LV end-diastolic volume, sphericity index and separation between papillary muscles, only gender, volume and twist were significant. Twist was the most powerful correlate (beta -2.23, CI -3.26 to -1.23 p < 0.001). In patients with FMR, peak systolic twist negatively correlates with RVol (r = -0.73, p < 0.0001).

CONCLUSION

Reduced rotational systolic LV motion is significantly and independently associated with RVol among patients with FMR, suggesting a novel pathophysiological mechanism and a potential therapeutic target.

Valvular regurgitation flow jet assessment using in vitro 4D flow MRI: Implication for mitral regurgitation

PURPOSE

The purpose of this study was to evaluate the accuracy of four-dimensional (4D) flow MRI for direct assessment of peak velocity, flow volume, and momentum of a mitral regurgitation (MR) flow jets using an in vitro pulsatile jet flow phantom. We systematically investigated the impact of spatial resolution and quantification location along the jet on flow quantities with Doppler ultrasound as a reference for peak velocity.

METHODS

Four-dimensional flow MRI data of a pulsatile jet through a circular, elliptical, and 3D-printed patient-specific MR orifice model was acquired with varying spatial resolution (1.5-5 mm isotropic voxel). Flow rate and momentum of the jet were quantified at various axial distances (x = 0-50 mm) and integrated over time to calculate Vol_jet and MTI_jet . In vivo assessment of Vol_jet and MTI_jet was performed on 3 MR patients.

RESULTS

Peak velocities were comparable to Doppler ultrasound (3% error, 1.5 mm voxel), but underestimated with decreasing spatial resolution (-40% error, 5 mm voxel). Vol_jet was similar to regurgitant volume (RVol) within 5 mm, and then increased linearly with the axial distance (19%/cm) because of flow entrainment. MTI_jet remained steady throughout the jet (2%/cm) as theoretically predicted. Four and 9 voxels across the jet were required to measure flow volume and momentum-time-integral within 10% error, respectively.

CONCLUSION

Four-dimensional flow MRI detected accurate peak velocity, flow rate, and momentum for in vitro MR-mimicking flow jets. Spatial resolution significantly impacted flow quantitation, which otherwise followed predictions of flow entrainment and momentum conservation. This study provides important preliminary information for accurate in vivo MR assessment using 4D flow MRI.

Accuracy of stroke volume measurement with phase-contrast cardiovascular magnetic resonance in patients with aortic stenosis

BACKGROUND

Phase contrast (PC) cardiovascular magnetic resonance (CMR) in the ascending aorta (AAo) is widely used to calculate left ventricular (LV) stroke volume (SV). The accuracy of PC CMR may be altered by turbulent flow. Measurement of SV at another site is suggested in the presence of aortic stenosis, but very few data validates the accuracy or inaccuracy of PC in that setting. Our objective is to compare flow measurements obtained in the AAo and LV outflow tract (LVOT) in patients with aortic stenosis.

METHODS

Retrospective analysis of patients with aortic stenosis who had CMR and echocardiography. Patients with mitral regurgitation were excluded. PC in the AAo and LVOT were acquired to derive SV. LV SV from end-systolic and end-diastolic tracings was used as the reference measure. A difference ≥ 10% between the volumetric method and PC derived SVs was considered discordant. Metrics of turbulence and jet eccentricity were assessed to explore the predictors of discordant measurements.

RESULTS

We included 88 patients, 41% with bicuspid aortic valve. LVOT SV was concordant with the volumetric method in 79 (90%) patients vs 52 (59%) patients for AAo SV (p = 0.015). In multivariate analysis, aortic stenosis flow jet angle was a strong predictor of discordant measurement in the AAo (p = 0.003). Mathematical correction for the jet angle improved the concordance from 59 to 91%. Concordance was comparable in patients with bicuspid and trileaflet valves (57% and 62% concordance respectively; p = 0.11). Accuracy of SV measured in the LVOT was not influenced by jet eccentricity. For aortic regurgitation quantification, PC in the AAo had better correlation to volumetric assessments than LVOT PC.

CONCLUSION

LVOT PC SV in patients with aortic stenosis and eccentric jet might be more accurate compared to the AAo SV. Mathematical correction for the jet angle in the AAo might be another alternative to improve accuracy.

Automatic Assessment of Mitral Regurgitation Severity Using the Mask R-CNN Algorithm with Color Doppler Echocardiography Images

Accurate assessment of mitral regurgitation (MR) severity is critical in clinical diagnosis and treatment. No single echocardiographic method has been recommended for MR quantification thus far. We sought to define the feasibility and accuracy of the mask regions with a convolutional neural network (Mask R-CNN) algorithm in the automatic qualitative evaluation of MR using color Doppler echocardiography images. The authors collected 1132 cases of MR from hospital A and 295 cases of MR from hospital B and divided them into the following four types according to the 2017 American Society of Echocardiography (ASE) guidelines: grade I (mild), grade II (moderate), grade III (moderate), and grade IV (severe). Both grade II and grade III are moderate. After image marking with the LabelMe software, a method using the Mask R-CNN algorithm based on deep learning (DL) was used to evaluate MR severity. We used the data from hospital A to build the artificial intelligence (AI) model and conduct internal verification, and we used the data from hospital B for external verification. According to severity, the accuracy of classification was 0.90, 0.89, and 0.91 for mild, moderate, and severe MR, respectively. The Macro F1 and Micro F1 coefficients were 0.91 and 0.92, respectively. According to grading, the accuracy of classification was 0.90, 0.87, 0.81, and 0.91 for grade I, grade II, grade III, and grade IV, respectively. The Macro F1 and Micro F1 coefficients were 0.89 and 0.89, respectively. Automatic assessment of MR severity is feasible with the Mask R-CNN algorithm and color Doppler electrocardiography images collected in accordance with the 2017 ASE guidelines, and the model demonstrates reasonable performance and provides reliable qualitative results for MR severity.

Advanced Cardiovascular Imaging in Clinical Heart Failure

Cardiovascular imaging is the cornerstone of the assessment of patients with heart failure. Although noninvasive volumetric estimation of the cardiac function is an essential and indisputably useful clinical tool, cardiac imaging has evolved and matured to offer detailed functional, hemodynamic, and tissue characterization. The adoption of a new framework to diagnose and phenotype heart failure that incorporates comprehensive imaging assessment has been lacking in clinical trials. The present review offers a general overview of available imaging strategies for patients with heart failure.

Quantification of regurgitation in mitral valve prolapse with four-dimensional flow cardiovascular magnetic resonance

BACKGROUND

Four-dimensional cardiovascular magnetic resonance (CMR) flow assessment (4D flow) allows to derive volumetric quantitative parameters in mitral regurgitation (MR) using retrospective valve tracking. However, prior studies have been conducted in functional MR or in patients with congenital heart disease, thus, data regarding the usefulness of 4D flow CMR in case of a valve pathology like mitral valve prolapse (MVP) are scarce. This study aimed to evaluate the clinical utility of cine-guided valve segmentation of 4D flow CMR in assessment of MR in MVP when compared to standardized routine CMR and transthoracic echocardiography (TTE).

METHODS

Six healthy subjects and 54 patients (55 ± 16 years; 47 men) with MVP were studied. TTE severity grading used a multiparametric approach resulting in mild/mild-moderate (n = 12), moderate-severe (n = 12), and severe MR (n = 30). Regurgitant volume (RVol) and regurgitant fraction (RF) were also derived using standard volumetric CMR and 4D flow CMR datasets with direct measurement of regurgitant flow (4DFdirect) and indirect calculation using the formula: mitral valve forward flow - left ventricular outflow tract stroke volume (4DFindirect).

RESULTS

There was moderate to strong correlation between methods (r = 0.59-0.84, p < 0.001), but TTE proximal isovelocity surface area (PISA) method showed higher RVol as compared with CMR techniques (PISA vs. CMR, mean difference of 15.8 ml [95% CI 9.9-21.6]; PISA vs. 4DFindirect, 17.2 ml [8.4-25.9]; PISA vs. 4DFdirect, 27.9 ml [19.1-36.8]; p < 0.001). Only indirect CMR methods (CMR vs. 4DFindirect) showed moderate to substantial agreement (Lin's coefficient 0.92-0.97) without significant bias (mean bias 1.05 ± 26 ml [- 50 to 52], p = 0.757). Intra- and inter-observer reliability were good to excellent for all methods (ICC 0.87-0.99), but with numerically lower coefficient of variation for indirect CMR methods (2.5 to 12%).

CONCLUSIONS

In the assessment of patients with MR and MVP, cine-guided valve segmentation 4D flow CMR is feasible and comparable to standard CMR, but with lower RVol when TTE is used as reference. 4DFindirect quantification has higher intra- and inter-technique agreement than 4DFdirect quantification and might be used as an adjunctive technique for cross-checking MR quantification in MVP.

The current diagnosis and treatment of high-risk patients with chronic primary and secondary mitral valve regurgitation

Mitral valve regurgitation (MR) is due primarily to either primary degeneration of the mitral valve with Barlow's or fibroelastic disease or is secondary to ischemic or nonischemic cardiomyopathies. Echocardiography is essential to assess MR etiology and severity, the remodeling of cardiac chambers and to characterize longitudinal chamber changes to determine optimal therapies. Surgery is recommended for severe primary MR if persistent symptoms are present or if left ventricle dysfunction is present with an EF <60% or a left ventricle end-systolic diameter ≥40 mm. For secondary MR, therapy of heart failure with vasodilators and diuretics improves forward cardiac output. Coronary artery bypass grafts (CABG) or percutaneous coronary intervention (PCI) should be considered for severe MR due to ischemia. This review summarizes the pathophysiology, the characteristics, the management and the different interventions for high risk patients with chronic primary and secondary MR.

The mitral regurgitation effects of cardiac structure and function in left ventricular noncompaction

This study evaluated the effects of mitral regurgitation (MR) on cardiac structure and function in left ventricular noncompaction (LVNC) patients. The clinical and cardiovascular magnetic resonance (CMR) data for 182 patients with noncompaction or hypertrabeculation from three institutes were retrospectively included. We analyzed the difference in left ventricular geometry, cardiac function between LVNC patients with and without MR. The results showed that patients with MR had a worse New York Heart Association (NYHA) class and a higher incidence of arrhythmia (P < 0.05). MR occurred in 48.2% of LVNC patients. Compared to LVNC patients without MR, the two-dimensional sphericity index, maximum/minimum end-diastolic ratio and longitudinal shortening in LVNC patients with MR were lower (P < 0.05), and the peak longitudinal strain (PLS) of the global and segmental myocardium were obviously reduced (P < 0.05). No significant difference was found in strain in LVNC patients with different degree of MR; end diastolic volume, end systolic volume, and global PLS were statistically associated with MR and NYHA class (P < 0.05), but the non-compacted to compacted myocardium ratio had no significant correlation with them. In conclusion, the presence of MR is common in LVNC patients. LVNC patients with MR feature more severe morphological and functional changes. Hypertrabeculation is not an important factor affecting structure and function at the heart failure stage.

Importance of Myocardial Fibrosis in Functional Mitral Regurgitation: From Outcomes to Decision-Making

Functional mitral regurgitation (FMR) is a common and complex valve disease, in which severity and risk stratification is still a conundrum. Although risk increases with FMR severity, it is modulated by subjacent left ventricular (LV) disease. The extent of LV remodeling and dysfunction is traditionally evaluated by echocardiography, but a growing body of evidence shows that myocardial fibrosis (MF) assessment by cardiac magnetic resonance (CMR) may complement risk stratification and inform treatment decisions. This review summarizes the current knowledge on the comprehensive evaluation that CMR can provide for patients with FMR, in particular for the assessment of MF and its potential impact in clinical decision-making.

Standard and emerging CMR methods for mitral regurgitation quantification

BACKGROUND

There are several methods to quantify mitral regurgitation (MR) by cardiovascular magnetic resonance (CMR). The interoperability of these methods and their reproducibility remains undetermined.

OBJECTIVE

To determine the agreement and reproducibility of different MR quantification methods by CMR across all aetiologies.

METHODS

Thirty-five patients with MR were recruited (primary MR = 12, secondary MR = 10 and MVR = 13). Patients underwent CMR, including cines and four-dimensional flow (4D flow). Four methods were evaluated: MR_Standard (left ventricular stroke volume - aortic forward flow by phase contrast), MR_LVRV (left ventricular stroke volume - right ventricular stroke volume), MR_Jet (direct jet quantification by 4D flow) and MR_MVAV (mitral forward flow by 4D flow - aortic forward flow by 4D flow). For all cases and MR types, 520 MR volumes were recorded by these 4 methods for intra-/inter-observer tests.

RESULTS

In primary MR, MR_MVAV and MR_LVRV were comparable to MR_Standard (P > 0.05). MR_Jet resulted in significantly higher MR volumes when compared to MR_Standard (P < 0.05) In secondary MR and MVR cases, all methods were comparable. In intra-observer tests, MR_MVAV demonstrated least bias with best limits of agreement (bias = -0.1 ml, -8 ml to 7.8 ml, P = 0.9) and best concordance correlation coefficient (CCC = 0.96, P < 0.01). In inter-observer tests, for primary MR and MVR, least bias and highest CCC were observed for MR_MVAV. For secondary MR, bias was lowest for MR_Jet (-0.1 ml, PNS).

CONCLUSION

CMR methods of MR quantification demonstrate agreement in secondary MR and MVR. In primary MR, this was not observed. Across all types of MR, MR_MVAV quantification demonstrated the highest reproducibility and consistency.

Selection of the Optimal Candidate to MitraClip for Secondary Mitral Regurgitation: Beyond Mitral Valve Morphology

Secondary mitral regurgitation (MR) occurs despite structurally normal valve apparatus due to an underlying disease of the myocardium leading to disruption of the balance between tethering and closing forces with ensuing failure of leaflet coaptation. In patients with heart failure (HF) and left ventricular dysfunction, secondary MR is independently associated with poor outcome, yet prognostic benefits related to the correction of MR have remained elusive. Surgery is not recommended for the correction of secondary MR outside coronary artery bypass grafting. Percutaneous mitral valve repair (PMVR) with MitraClip implantation has recently evolved as a new transcatheter treatment option of inoperable or high-risk patients with severe MR, with promising results supporting the extension of guideline recommendations. MitraClip is highly effective in reducing secondary MR in HF patients. However, the derived clinical benefit is still controversial as two randomized trials directly comparing PMVR vs. optimal medical therapy in severe secondary MR yielded virtually opposite conclusions. We reviewed current evidence to identify predictors of PMVR-related outcomes in secondary MR useful to improve the timing and the selection of patients who would derive maximal benefit from MitraClip intervention. Beyond mitral valve anatomy, optimal candidate selection should rely on a comprehensive diagnostic workup and a fine-tuned risk stratification process aimed at (i) recognizing the substantial heterogeneity of secondary MR and its complex interaction with the myocardium, (ii) foreseeing hemodynamic consequences of PMVR, (iii) anticipating futility and (iv) improving symptoms, quality of life and overall survival.

Cardiovascular Magnetic Resonance in Valvular Heart Disease-Related Heart Failure

Patients with valvular heart disease-related heart failure are unable to pump enough blood to meet the body's needs. Magnetic resonance imaging (MRI) can play an important role by identifying these patients and distinguishing them from patients whose valvular disease is not the cause of their heart failure. Heart failure is a major public health problem, with a prevalence of 5.8 million people in the United States and more than 223 million people worldwide. This article focuses on the diagnostic and prognostic value of MRI patients with valvular causes of heart failure.

Intracardiac and Vascular Hemodynamics with Cardiovascular Magnetic Resonance in Heart Failure

In heart failure (HF), the impaired heart loses its ability to competently eject blood during systole or fill with blood during diastole, manifesting in multifaceted abnormal intracardiac or intravascular flow dynamics. Conventional imaging techniques are limited in their ability to evaluate multidirectional multidimensional flow alterations in HF. Four-dimensional (4-D) flow magnetic resonance imaging (MRI) has emerged as a promising technique to comprehensively visualize and quantify changes in 3-dimensional blood flow dynamics in complex cardiovascular diseases. This article reviews emerging applications of 4-D flow MRI hemodynamic markers in HF and etiologies at risk of progressing to HF.

Thoracic Manifestations of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is one of the most common chronic systemic inflammatory diseases and the most common chronic inflammatory arthritis. Classically a progressive symmetric polyarthritis, RA is characterized by inflammation, erosions, bone loss, and joint destruction. Up to half of patients with RA exhibit extra-articular manifestations (EAMs), which may precede articular disease and are more common in patients with seropositive RA (patients with detectable serum levels of rheumatoid factor and/or anticitrullinated peptide antibodies). Cardiovascular and pulmonary EAMs are the largest contributors to morbidity and mortality in RA and may be especially devastating. Imaging has a significant role in diagnosing these EAMs and assessing response to treatment. Although treatment with disease-modifying antirheumatic drugs has redefined the natural history of RA and helped many patients achieve low disease activity, patients are at risk for treatment-related complications, as well as infections. The clinical features of drug-induced lung disease and infection can overlap considerably with those of EAMs, presenting a diagnostic challenge. Radiologists, by recognizing the imaging characteristics and evolution of these various processes, are essential in diagnosing and distinguishing among EAMs, treatment-related complications, and unrelated processes and formulating an appropriate differential diagnosis. Moreover, recognizing these disease processes at imaging and contextualizing imaging findings with clinical information and laboratory and pathologic findings can facilitate definitive diagnosis and proper treatment. The authors review the articular and extra-articular thoracic imaging manifestations of RA, including cardiovascular, respiratory, and pleural diseases, as well as treatment-related complications and common infections. ^©RSNA, 2021.

Imaging the mitral valve: a primer for the interventional surgeon

Transcatheter mitral valve interventions (TMVI) have evolved over the past decade as alternatives to open surgical repair for the therapeutic management of patients with severe mitral regurgitation (MR). Concurrent with the development of these technologies, quality multi-modality cardiac imaging has become essential in patient selection and procedural guidance. The former involves assessments of the pathophysiologic mechanisms of regurgitation, valvular anatomy and morphology, as well as objective quantification of the severity of MR. Both transthoracic and transesophageal echocardiography (TEE) are crucial and serve as the gateway to diagnosis and management of mitral valvular disease. Along with multi-detector computed tomography (CT) and cardiac magnetic resonance imaging (CMR), echocardiography plays an important role for preprocedural planning and evaluation of the spatial relationships of the mitral valvular complex with the coronary sinus, circumflex coronary artery and left ventricular (LV) outflow tract. Procedures that target mitral leaflets (e.g., MitraClip, PASCAL) or annulus (e.g., Cardioband, Carillon), or provide chordal (e.g., NeoChord, Harpoon) or valvular replacement, tend to be guided by TEE and assisted by fluoroscopy. As newer devices become available and outcomes of TMVI improve, cardiac imaging will undoubtedly continue to play an essential role in the success of percutaneous mitral valve repair (MVr) and replacement. The interventional surgeon of the future must therefore have a thorough understanding of the various imaging modalities while synthesizing and integrating novel concepts (e.g., neo-LV outflow tract) as applicable to assessing valvular function and pathology.

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.

Cardiac magnetic resonance systematically overestimates mitral regurgitations by the indirect method

Objective

Cardiac MRI is quickly emerging as the gold standard for assessment of mitral regurgitation, most commonly with the indirect method subtracting forward flow in aorta from volumetric segmentation of the left ventricle. We aimed to investigate how aortic flow measurements with increasing distance from the aortic valve affect calculated mitral regurgitations and whether measurements were influenced by breath-hold regimen.

Methods

Free-breathing and breath-hold phase contrast flows were measured in aorta at valve level, sinotubular (ST) junction, mid-ascending aorta and in the pulmonary trunk. Flow measurements were pairwise compared, and subsequently, after exclusion of patients with visible mitral and tricuspid regurgitations for left-sided and right-sided comparisons, respectively, flow-measured stroke volumes were compared with ventricular volumetric segmentations.

Results

Thirty-nine participants without arrhythmias or structural abnormalities of the large vessels were included. Stroke volumes measured with free-breathing and breath-hold flow decreased equally with increasing distance to the aortic valves (breath-hold flow: aortic valve 105.6±20.8 mL, ST junction 101.5±20.7 mL, mid-ascending aorta 98.1±21.5 mL). After exclusion of atrioventricular regurgitations, stroke volumes determined by volumetric measurements were higher compared with values determined by flow measurements, corresponding to ‘false’ atrioventricular regurgitations of 8.0%±5.8% with flow measured at valve level, 11.6%±5.2% at the ST junction and 15.3%±5.0% at the mid-ascending aorta.

Conclusions

Stroke volumes determined by flow decrease throughout the proximal aorta and are systematically lower than volumetrically measured stroke volumes. The indirect method systematically overestimates mitral regurgitations, especially with increasing distance from the aortic valves.

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.

SCMR Position Paper (2020) on clinical indications for cardiovascular magnetic resonance

The Society for Cardiovascular Magnetic Resonance (SCMR) last published its comprehensive expert panel report of clinical indications for CMR in 2004. This new Consensus Panel report brings those indications up to date for 2020 and includes the very substantial increase in scanning techniques, clinical applicability and adoption of CMR worldwide. We have used a nearly identical grading system for indications as in 2004 to ensure comparability with the previous report but have added the presence of randomized controlled trials as evidence for level 1 indications. In addition to the text, tables of the consensus indication levels are included for rapid assimilation and illustrative figures of some key techniques are provided.

Cardiac magnetic resonance imaging with standard imaging planes for mitral valve scallop pathology: interrater agreement and comparison with echocardiography

Magnetic resonance imaging (CMR) is applied in mitral valve regurgitation (MR) to quantify regurgitation volume/fraction and cardiac volumes, but individual scallop pathology is evaluated by echocardiography. To evaluate CMR for determination of individual scallop pathology, interrater variability on evaluation of scallop pathology from echocardiography and a standard clinical CMR protocol including a transversal stack was compared. 318 mitral scallops from 53 patients with primary MR were evaluated by two cardiologists evaluating echocardiography scans and two other cardiologists evaluating CMR scans (blinded). Inter-rater variability was determined with percentage agreement and Cohen's kappa. In evaluable scallops, interrater agreement on the diagnosis of a prolapsing and/or flail scallop was 77-87% and kappa values of 0.27-0.67, irrespective of physician or modality. Important differences between modalities were primarily related to CMR-evaluators judging the A3 and the P3 to be normal when echocardiography demonstrated prolapsing or even flail scallops; poor imaging of calcification; and flailed scallops occasionally being undetected with CMR since the flow-voids may mask the scallop. Inter-rater agreement for scallop pathology in primary MR is comparable for echocardiography and standard magnetic resonance imaging scans, but CMR has important pitfalls relating to evaluation of A3 and P3 scallops, and suffers from poor visualization of calcification and lower spatial resolution than echo. CMR with standard planes cannot replace CMR with longitudinal planes or echo for the evaluation of specific scallop pathology in severe primary MR.

Timing of intervention in asymptomatic patients with valvular heart disease

Current management of valvular heart disease (VHD) seeks to optimize long-term outcome by timely intervention. Recommendations for treatment of patients with symptoms due to severe valvular disease are based on a foundation of solid evidence. However, when to intervene in asymptomatic patients remains controversial and decision requires careful individual weighing of the potential benefits against the risk of intervention and its long-term consequences. The primary rationale for earlier intervention is prevention of irreversible left ventricular (LV) myocardial changes that might result in later clinical symptoms and adverse cardiac events. A number of outcome predictors have been identified that facilitate decision-making. This review summarizes current recommendations and discusses recently published data that challenge them suggesting even earlier intervention. In adults with asymptomatic aortic stenosis (AS), emerging risk markers include very severe valve obstruction, elevated serum natriuretic peptide levels, and imaging evidence of myocardial fibrosis or increased extracellular myocardial volume. Currently, transcatheter aortic valve implantation (TAVI) is not recommended for treatment of asymptomatic severe AS although this may change in the future. In patients with aortic regurgitation (AR), the potential benefit of early intervention in preventing LV dilation and dysfunction must be balanced against the long-term risk of a prosthetic valve, a particular concern because severe AR often occurs in younger patients with a congenital bicuspid valve. In patients with mitral stenosis, the option of transcatheter mitral balloon valvotomy tilts the balance towards earlier intervention to prevent atrial fibrillation, embolic events, and pulmonary hypertension. When chronic severe mitral regurgitation is due to mitral valve prolapse, anatomic features consistent with a high likelihood of a successful and durable valve repair favour early intervention. The optimal timing of intervention in adults with VHD is a constantly changing threshold that depends not only on the severity of valve disease but also on the safety, efficacy, and long-term durability of our treatment options.

Cardiac Magnetic Resonance in Valvular Heart Disease: Assessment of Severity and Myocardial Remodeling

Cardiac magnetic resonance (CMR) has emerged as the gold standard in assessing ventricular mass, volume, and systolic function. Due to these and other strengths, CMR has increasingly been used to study valvular heart disease (VHD) and resultant cardiac remodeling. By using CMR to assess flow, limitations in echocardiographic assessment of VHD can be overcome, particularly in regurgitant lesions. The following article reviews the current role of CMR imaging in studying disease severity and myocardial remodeling in patients with VHD.