Prognostic Implications of Magnetic Resonance-Derived Quantification in Asymptomatic Patients With Organic Mitral Regurgitation: Comparison With Doppler Echocardiography-Derived Integrative Approach

Mitral Annular Disease at Cardiac MRI: What to Know and Look For

Accurate evaluation of the mitral valve (MV) apparatus is essential for understanding the mechanisms of MV disease across various clinical scenarios. The mitral annulus (MA) is a complex and crucial structure that supports MV function; however, conventional imaging techniques have limitations in fully capturing the entirety of the MA. Moreover, recognizing annular changes might aid in identifying patients who may benefit from advanced cardiac imaging and interventions. Multimodality cardiovascular imaging plays a major role in the diagnosis, prognosis, and management of MV disease. Transthoracic echocardiography is the first-line modality for evaluation of the MA, but it has limitations. Cardiac MRI (CMR) has emerged as a robust imaging modality for assessing annular changes, with distinct advantages over other imaging techniques, including accurate flow and volumetric quantification and assessment of variations in the measurements and shape of the MA during the cardiac cycle. Mitral annular disjunction (MAD) is defined as atrial displacement of the hinge point of the MV annulus away from the ventricular myocardium, a condition that is now more frequently diagnosed and studied owing to recent technical advances in cardiac imaging. However, several unresolved issues regarding MAD, such as the functional significance of pathologic disjunction and how this disjunction advances in the clinical course, require further investigation. The authors review the role of CMR in the assessment of MA disease, with a focus on MAD and its functional implications in MV prolapse and mitral regurgitation. ©RSNA, 2024 Supplemental material is available for this article. See the invited commentary by Stojanovska and Fujikura in this issue.

Mitral regurgitation assessment by cardiovascular magnetic resonance imaging during continuous in-scanner exercise: a feasibility study

PURPOSE

Exercise imaging using current modalities can be challenging. This was patient focused study to establish the feasibility and reproducibility of exercise-cardiovascular magnetic resonance imaging (EX-CMR) acquired during continuous in-scanner exercise in asymptomatic patients with primary mitral regurgitation (MR).

METHODS

This was a prospective, feasibility study. Biventricular volumes/function, aortic flow volume, MR volume (MR-Rvol) and regurgitant fraction (MR-RF) were assessed at rest and during low- (Low-EX) and moderate-intensity exercise (Mod-EX) in asymptomatic patients with primary MR.

RESULTS

Twenty-five patients completed EX-CMR without complications. Whilst there were no significant changes in the left ventricular (LV) volumes, there was a significant increase in the LVEF (rest 63 ± 5% vs. Mod-EX 68 ± 6%;p = 0.01). There was a significant reduction in the right ventricular (RV) end-systolic volume (rest 68 ml(60-75) vs. Mod-EX 46 ml(39-59);p < 0.001) and a significant increase in the RV ejection fraction (rest 55 ± 5% vs. Mod-EX 65 ± 8%;p < 0.001). Whilst overall, there were no significant group changes in the MR-Rvol and MR-RF, individual responses were variable, with MR-Rvol increasing by ≥ 15 ml in 4(16%) patients and decreasing by ≥ 15 ml in 9(36%) of patients. The intra- and inter-observer reproducibility of LV volumes and aortic flow measurements were excellent, including at Mod-EX.

CONCLUSION

EX-CMR is feasible and reproducible in patients with primary MR. During exercise, there is an increase in the LV and RV ejection fraction, reduction in the RV end-systolic volume and a variable response of MR-Rvol and MR-RF. Understanding the individual variability in MR-Rvol and MR-RF during physiological exercise may be clinically important.

Review and critical appraisal of the indications for cardiac magnetic resonance imaging in the ESC guidelines

Cardiac MRI has made significant advances in the past decade, becoming an important technique for the evaluation of various cardiac pathologies. The aim of this document is to review the current indications for performing cardiac MRI based on the current ESC guidelines for STEMI, NSTEMI, chronic coronary artery disease, heart failure, arrhythmias, sudden cardiac death, valvular heart disease, pericardial disease and congenital heart disease. The review discusses the diagnostic and prognostic value of cMR for numerous cardiac diseases, and its important value in assessing structural heart disease and predicting arrhythmia risk. Additionally, it reflects upon the appropriateness of the guidelines and points out areas where the indications should be revised in future editions, based on the author's personal opinion. It is suggested that guideline criteria for the use of cMR should be more explicit to promote its use and lead to more specific reimbursements. However, further studies are needed to even better document the value of cMR in the future.

Degenerative mitral regurgitation

Degenerative mitral regurgitation is a major threat to public health and affects at least 24 million people worldwide, with an estimated 0.88 million disability-adjusted life years and 34,000 deaths in 2019. Improving access to diagnostic testing and to timely curative therapies such as surgical mitral valve repair will improve the outcomes of many individuals. Imaging such as echocardiography and cardiac magnetic resonance allow accurate diagnosis and have provided new insights for a better definition of the most appropriate timing for intervention. Advances in surgical techniques allow minimally invasive treatment with durable results that last for ≥20 years. Transcatheter therapies can provide good results in select patients who are considered high risk for surgery and have a suitable anatomy; the durability of such repairs is up to 5 years. Translational science has provided new knowledge on the pathophysiology of degenerative mitral regurgitation and may pave the road to the development of medical therapies that could be used to halt the progression of the disease.

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.

Machine Learning-Based Phenogrouping in MVP Identifies Profiles Associated With Myocardial Fibrosis and Cardiovascular Events

BACKGROUND

Structural changes and myocardial fibrosis quantification by cardiac imaging have become increasingly important to predict cardiovascular events in patients with mitral valve prolapse (MVP). In this setting, it is likely that an unsupervised approach using machine learning may improve their risk assessment.

OBJECTIVES

This study used machine learning to improve the risk assessment of patients with MVP by identifying echocardiographic phenotypes and their respective association with myocardial fibrosis and prognosis.

METHODS

Clusters were constructed using echocardiographic variables in a bicentric cohort of patients with MVP (n = 429, age 54 ± 15 years) and subsequently investigated for their association with myocardial fibrosis (assessed by cardiac magnetic resonance) and cardiovascular outcomes.

RESULTS

Mitral regurgitation (MR) was severe in 195 (45%) patients. Four clusters were identified: cluster 1 comprised no remodeling with mainly mild MR, cluster 2 was a transitional cluster, cluster 3 included significant left ventricular (LV) and left atrial (LA) remodeling with severe MR, and cluster 4 included remodeling with a drop in LV systolic strain. Clusters 3 and 4 featured more myocardial fibrosis than clusters 1 and 2 (P < 0.0001) and were associated with higher rates of cardiovascular events. Cluster analysis significantly improved diagnostic accuracy over conventional analysis. The decision tree identified the severity of MR along with LV systolic strain <21% and indexed LA volume >42 mL/m2 as the 3 most relevant variables to correctly classify participants into 1 of the echocardiographic profiles.

CONCLUSIONS

Clustering enabled the identification of 4 clusters with distinct echocardiographic LV and LA remodeling profiles associated with myocardial fibrosis and clinical outcomes. Our findings suggest that a simple algorithm based on only 3 key variables (severity of MR, LV systolic strain, and indexed LA volume) may help risk stratification and decision making in patients with MVP. (Genetic and Phenotypic Characteristics of Mitral Valve Prolapse, NCT03884426; Myocardial Characterization of Arrhythmogenic Mitral Valve Prolapse [MVP STAMP], NCT02879825).

Pitfalls of mitral regurgitation assessment in the presence of mitral valve prolapse

Adequate grading of mitral regurgitation (MR) in patients with mitral valve prolapse (MVP) in the presence of mid-late systolic jets can represent a major challenge. In this entity, jets are commonly overestimated by echocardiography. Correct quantification is crucial and highly relevant for the further management and prognosis of these oftentimes young patients. This case points out potential pitfalls and underlines the importance to systematically include qualitative, quantitative, and semi-quantitative parameters into the echocardiographic assessment.

Cardiac reverse remodeling in primary mitral regurgitation: mitral valve replacement vs. mitral valve repair

BACKGROUND

When feasible, guidelines recommend mitral valve repair (MVr) over mitral valve replacement (MVR) to treat primary mitral regurgitation (MR), based upon historic outcome studies and transthoracic echocardiography (TTE) reverse remodeling studies. Cardiovascular magnetic resonance (CMR) offers reference standard biventricular assessment with superior MR quantification compared to TTE. Using serial CMR in primary MR patients, we aimed to investigate cardiac reverse remodeling and residual MR post-MVr vs MVR with chordal preservation.

METHODS

83 patients with ≥ moderate-severe MR on TTE were prospectively recruited. 6-min walk tests (6MWT) and CMR imaging including cine imaging, aortic/pulmonary through-plane phase contrast imaging, T1 maps and late-gadolinium-enhanced (LGE) imaging were performed at baseline and 6 months after mitral surgery or watchful waiting (control group).

RESULTS

72 patients completed follow-up (Controls = 20, MVr = 30 and MVR = 22). Surgical groups demonstrated comparable baseline cardiac indices and co-morbidities. At 6-months, MVr and MVR groups demonstrated comparable improvements in 6MWT distances (+ 57 ± 54 m vs + 64 ± 76 m respectively, p = 1), reduced indexed left ventricular end-diastolic volumes (LVEDVi; - 29 ± 21 ml/m2 vs - 37 ± 22 ml/m2 respectively, p = 0.584) and left atrial volumes (- 23 ± 30 ml/m2 and - 39 ± 26 ml/m2 respectively, p = 0.545). At 6-months, compared with controls, right ventricular ejection fraction was poorer post-MVr (47 ± 6.1% vs 53 ± 8.0% respectively, p = 0.01) compared to post-MVR (50 ± 5.7% vs 53 ± 8.0% respectively, p = 0.698). MVR resulted in lower residual MR-regurgitant fraction (RF) than MVr (12 ± 8.0% vs 21 ± 11% respectively, p = 0.022). Baseline and follow-up indices of diffuse and focal myocardial fibrosis (Native T1 relaxation times, extra-cellular volume and quantified LGE respectively) were comparable between groups. Stepwise multiple linear regression of indexed variables in the surgical groups demonstrated baseline indexed mitral regurgitant volume as the sole multivariate predictor of left ventricular (LV) end-diastolic reverse remodelling, baseline LVEDVi as the most significant independent multivariate predictor of follow-up LVEDVi, baseline indexed LV end-systolic volume as the sole multivariate predictor of follow-up LV ejection fraction and undergoing MVR (vs MVr) as the most significant (p < 0.001) baseline multivariate predictor of lower residual MR.

CONCLUSION

In primary MR, MVR with chordal preservation may offer comparable cardiac reverse remodeling and functional benefits at 6-months when compared to MVr. Larger, multicenter CMR studies are required, which if the findings are confirmed could impact future surgical practice.

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.

Quantification of primary mitral regurgitation by echocardiography: A practical appraisal

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

Effects of Mitral Valve Prolapse on Quantification of Mitral Regurgitation and Ejection Fraction Using Cardiac MRI

Purpose

To determine the impact of prolapsed volume on regurgitant volume (RegV), regurgitant fraction (RF), and left ventricular ejection fraction (LVEF) in patients with mitral valve prolapse (MVP) using cardiac MRI.

Materials and Methods

Patients with MVP and mitral regurgitation who underwent cardiac MRI from 2005 to 2020 were identified retrospectively from the electronic record. RegV is the difference between left ventricular stroke volume (LVSV) and aortic flow. Left ventricular end-systolic volume (LVESV) and LVSV were obtained from volumetric cine images, with prolapsed volume inclusion (LVESVp, LVSVp) and exclusion (LVESVa, LVSVa) providing two estimates of RegV (RegVp, RegVa), RF (RFp, RFa), and LVEF (LVEFa, LVEFp). Interobserver agreement for LVESVp was assessed using intraclass correlation coefficient (ICC). RegV was also calculated independently using measurements from mitral inflow and aortic net flow phase-contrast imaging as the reference standard (RegVg).

Results

The study included 19 patients (mean age, 28 years ± 16 [SD]; 10 male patients). Interobserver agreement for LVESVp was high (ICC, 0.98; 95% CI: 0.96, 0.99). Prolapsed volume inclusion resulted in higher LVESV (LVESVp: 95.4 mL ± 34.7 vs LVESVa: 82.4 mL ± 33.8; P < .001), lower LVSV (LVSVp: 100.5 mL ± 33.8 vs LVSVa: 113.5 mL ± 35.9; P < .001), and lower LVEF (LVEFp: 51.7% ± 5.7 vs LVEFa: 58.6% ± 6.3; P < .001). RegV was larger in magnitude when prolapsed volume was excluded (RegVa: 39.4 mL ± 21.0 vs RegVg: 25.8 mL ± 22.8; P = .02), with no evidence of a difference when including prolapsed volume (RegVp: 26.4 mL ± 16.4 vs RegVg: 25.8 mL ± 22.8; P > .99).

Conclusion

Measurements that included prolapsed volume most closely reflected mitral regurgitation severity, but inclusion of this volume resulted in a lower LVEF.Keywords: Cardiac, MRI© RSNA, 2023See also commentary by Lee and Markl in this issue.

The evolving role of cardiovascular magnetic resonance in the assessment of mitral valve prolapse

Mitral valve prolapse (MVP), characterized by a displacement > 2 mm above the mitral annulus of one or both bileaflets, with or without leaflet thickening, is a common valvular heart disease, with a prevalence of approximately 2% in western countries. Although this population has a generally good overall prognosis, MVP can be associated with mitral regurgitation (MR), left ventricular (LV) remodeling leading to heart failure, ventricular arrhythmia, and, the most devastating complication, sudden cardiac death, especially in myxomatous bileaflet prolapse (Barlow's disease). Among several prognostic factors reported in the literature, LV fibrosis and mitral annular disjunction may act as an arrhythmogenic substrate in this population. Cardiac magnetic resonance (CMR) has emerged as a reliable tool for assessing MVP, MR severity, LV remodeling, and fibrosis. Indeed, CMR is the gold standard imaging modality to assess ventricular volume, function, and wall motion abnormalities; it allows accurate calculation of the regurgitant volume and regurgitant fraction in MR using a combination of LV volumetric measurement and aortic flow quantification, independent of regurgitant jet morphology and valid in cases of multiple valvulopathies. Moreover, CMR is a unique imaging modality that can assess non-invasively focal and diffuse fibrosis using late gadolinium enhancement sequences and, more recently, T1 mapping. This review describes the use of CMR in patients with MVP and its role in identifying patients at high risk of ventricular arrhythmia.

Valvular heart disease: shifting the focus to the myocardium

Adverse cardiac remodelling is the main determinant of patient prognosis in degenerative valvular heart disease (VHD). However, to give an indication for valvular intervention, current guidelines include parameters of cardiac chamber dilatation or function which are subject to variability, do not directly reflect myocardial structural changes, and, more importantly, seem to be not sensitive enough in depicting early signs of myocardial dysfunction before irreversible myocardial damage has occurred. To avoid irreversible myocardial dysfunction, novel biomarkers are advocated to help refining indications for intervention and risk stratification. Advanced echocardiographic modalities, including strain analysis, and magnetic resonance imaging have shown to be promising in providing new tools to depict the important switch from adaptive to maladaptive myocardial changes in response to severe VHD. This review, therefore, summarizes the current available evidence on the role of these new imaging biomarkers in degenerative VHD, aiming at shifting the clinical perspective from a valve-centred to a myocardium-focused approach for patient management and therapeutic decision-making.

An Integrative, Multiparametric Approach to Mitral Regurgitation Evaluation

Echocardiography is the first-line modality for assessing mitral regurgitation (MR). In addition to evaluation of the MR jet characteristics, echocardiography can provide quantitative parameters of MR severity. This case series illustrates the importance of integrating multiple parameters in the evaluation of MR and the role of multimodality imaging. (Level of Difficulty: Advanced.)

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.

Mitral regurgitation management: a systematic review of clinical practice guidelines and recommendations

Multiple guidelines exist for the diagnosis and management of mitral regurgitation (MR), the second most common valvular heart disease in high-income countries, with recommendations that do not always match. We systematically reviewed guidelines on diagnosis and management of MR, highlighting similarities and differences to guide clinical decision-making. We searched national and international guidelines in MEDLINE and EMBASE (1 June 2010 to 1 September 2021), the Guidelines International Network, National Guideline Clearinghouse, National Library for Health Guidelines Finder, Canadian Medical Association Clinical Practice Guidelines Infobase, and websites of relevant organizations. Two reviewers independently screened the abstracts and identified articles of interest. Guidelines that were rigorously developed (as assessed with the Appraisal of Guidelines for Research and Evaluation II instrument) were retained for analysis. Five guidelines were retained. There was consensus on a multidisciplinary approach from the heart team and for the definition and grading of severe primary MR. There was general agreement on the thresholds for intervention in symptomatic and asymptomatic primary MR; however, discrepancies were present. There was agreement on optimization of medical therapy in severe secondary MR and intervention in patients symptomatic despite optimal medical therapy, but no consensus on the choice of intervention (surgical repair/replacement vs. transcatheter approach). Cut-offs for high-risk intervention in MR, risk stratification of progressive MR, and guidance on mixed valvular disease were sparse.

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.

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.

Malignant Mitral Valve Prolapse: Risk and Prevention of Sudden Cardiac Death

Purpose of review

The purpose of this review is to explore the prevalence and risk factors for a malignant phenotype in mitral valve prolapse (MVP) characterized by life-threatening ventricular arrhythmias and sudden cardiac arrest and death (SCD), including mechanistic and pathophysiologic findings and mechanism-based potential therapies.

Recent findings

A malignant phenotype in MVP characterized by life-threatening arrhythmias has long been recognized, although MVP is often benign. Efforts to identify this malignant phenotype have revealed potential risk factors for SCD that include elongated, myxomatous leaflets, ECG changes and complex ventricular ectopy. More recently, malignant MVP has been associated with myocardial fibrosis in the papillary muscles and inferobasal left ventricular wall. This localization suggests a central role of prolapse-induced mechanical forces on the myocardium in creating an arrhythmogenic substrate and triggering life-threatening arrhythmias. This mechanism for fibrosis is also consistent with imaging evidence of prolapse-induced mechanical changes in the papillary muscles and inferobasal left ventricular wall. Currently, no therapy to prevent SCD in malignant MVP has been established and limited clinical data are available. Mechanistic information and prospective study have the potential to identify patients at risk of SCD and preventive strategies.

Summary

Malignant MVP relates to unique properties and mechanical abnormalities in the mitral valve apparatus and adjacent myocardium. Increased understanding of disease mechanisms and determinants of arrhythmias is needed to establish effective therapies.

Characterization of Primary Mitral Regurgitation With Flail Leaflet and/or Wall-Impinging Flow

BACKGROUND

Echocardiography guidelines note that a flail leaflet is a specific criterion for severe mitral regurgitation (MR) and that regurgitant severity is underestimated in wall-impinging jets (Coandă effect). Both findings are often considered to be pathognomonic of severe MR.

OBJECTIVES

In this study, the authors sought to determine the association of flail leaflet and Coandă effect with MR severity quantified by means of cardiac magnetic resonance (CMR).

METHODS

The authors enrolled 158 consecutive patients with primary MR according to echocardiography and CMR. The presence of a flail leaflet or Coandă was determined for each patient. CMR regurgitant volume (RV) and regurgitant fraction (RF) were quantified for all patients.

RESULTS

There were 55 patients (35%) with a flail leaflet, 52 (33%) with Coandă, and 22 (14%) with a flail leaflet and Coandă. The mean CMR mitral RV and RF progressively increased in patients without a Coandă or flail, a Coandă, a flail, or a Coandă and a flail (RV: 28 ± 21 mL vs 43 ± 23 mL vs 58 ± 29 mL vs 64 ± 25 mL [P < 0.001]; RF: 25% ± 16% vs 34% ± 14% vs 41% ± 12% vs 45% ± 12% [P < 0.001]). With the use of CMR RV, 35%, 46%, and 59% of patients had severe MR with the presence of a Coandă, flail leaflet, or both, respectively. With the use of CMR RF, 25%, 31%, and 40% of patients had severe MR with the presence of a Coandă, flail leaflet, or both, respectively.

CONCLUSIONS

While the presence of a flail leaflet and Coandă effect on echocardiography are associated with higher regurgitant volumes and fractions, they are frequently not associated with severe MR as assessed by means of CMR. (Comparison Study of Echocardiography and Cardiovascular Magnetic Resonance Imaging in the Assessment of Mitral and Aortic Regurgitation; NCT04038879).

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.

Comprehensive mitral valve prolapse assessment by cardiovascular MRI

Mitral valve (MV) prolapse (MVP) is a not fully understood common MV disorder. The development of sophisticated cardiovascular magnetic resonance imaging (CMRI) sequences over the last decades has allowed a more detailed assessment and provided better understanding of the pathophysiology of MVP to guide management, interventions, and risk stratification of patients affected. This review provides an overview of the most recent insights about this multifaceted pathology, particularly regarding the emerging concepts of mitral annular disjunction (MAD), and risk of arrhythmia and sudden death associated with myocardial fibrosis. We describe the emerging role of CMRI in both diagnosis and, more importantly, risk assessment of this disease, aiming to provide a comprehensive protocol for the assessment of MVP, which could represent a practical guide to clinicians and MRI practitioners working in the field.

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.

Gender differences in primary mitral regurgitant volumes at specific regurgitant fractions as assessed by magnetic resonance imaging

Guidelines suggest using a regurgitant fraction of 50% and regurgitant volume of 60 ml for determination of severe mitral insufficiency. Recent MRI data has suggested that a regurgitant fraction of 40% defines severe primary mitral insufficiency. We sought to determine whether there were gender differences in primary mitral regurgitant volumes for regurgitant fractions of 40% and 50%. A database search identified 394 patients that had MRI with a mitral regurgitant volume ≥ 10 ml or a study indication of mitral insufficiency. Chart review identified 97 patients with primary mitral insufficiency. Of these patients, 53 (54%) were women. Men had significantly larger left ventricular volumes, myocardial mass, stroke volumes and mitral regurgitant volumes (37 ± 25 ml vs. 24 ± 12 ml). The difference in regurgitant fraction between genders was not significant (27 ± 14% vs. 24 ± 11%; p-value = 0.24). Regurgitant fraction and regurgitant volume had a strong linear correlation in both men (r = .95) and women (r = .92). Despite similar linear correlations, the slope-intercept equations differed significantly between men and women (p < .001). A regurgitant fraction of 40% correlated with a regurgitant volume of 59 ml in men and 39.5 ml in women, while a regurgitant fraction of 50% correlated with a regurgitant volume of 76.2 ml in men and 49.6 ml in women. Regurgitant fraction, determined by cardiac MRI, provides a gender independent assessment of primary mitral insufficiency, and suggests that regurgitant volume thresholds for severe primary mitral insufficiency may be lower in women.

Comparison of mitral regurgitation severity assessments based on magnetic resonance imaging and echocardiography in patients with hypertrophic cardiomyopathy

Mitral regurgitation (MR), which is one of the factors responsible for heart failure symptoms and the development of atrial fibrillation, is an important feature of hypertrophic cardiomyopathy (HCM), and its presence affects which treatment options are chosen. Although cardiac magnetic resonance imaging (MRI) is considered the reference standard for assessing the regurgitant volume (RV) and fraction (RF), echocardiography is the most common method for assessing MR severity. Accordingly, the aim of this study was to compare the results of echocardiography and cardiac MRI for assessing MR severity in a cohort of patients with HCM. MR severity was assessed in 53 patients using cardiac MRI by determining the mitral RV (MRV) and mitral RF (MRF). The results were graded according to thresholds recommended in current guidelines. MR severity assessed by echocardiography was graded by integrating indices of severity. Greater than mild MR, as assessed using echocardiography, was present in 22 patients (41.5%) with HCM and in none of the control patients (p = 0.001). In all, 31 patients (58.5%) had no more than mild MR. When MR severity was assessed using different methods, either moderate (kappa = 0.44, 95% confidence interval = 0.21–0.67), poor or no agreement was found between MRI-derived and echocardiography-derived grades. HCM patients with echocardiography-derived moderate and severe MR had similar median MRVs and MRFs (p = 0.59 and p = 0.11, respectively). In HCM patients, cardiac MRI and echocardiography were at most in modest agreement in assessing MR severity. Importantly, echocardiography-derived moderate and severe MR were not distinguishable by either MRV or MRF.

Appropriate use criteria for cardiovascular MRI: SIC - SIRM position paper Part 2 (myocarditis, pericardial disease, cardiomyopathies and valvular heart disease)

Cardiovascular magnetic resonance (CMR) has emerged as an accurate diagnostic technique for the evaluation of patients with cardiac disease in the majority of clinical settings, thanks to an established additional diagnostic and prognostic value. This document has been developed by a joined group of experts of the Italian Society of Cardiology (SIC) and Italian Society of Radiology (SIRM) to provide a summary about the current state of technology and clinical applications of CMR, to improve the clinical diagnostic pathways and to promote its inclusion in clinical practice. The writing committee consisted of members and experts of both societies in order to develop a more integrated approach in the field of cardiac imaging. This section 2 will cover myocarditis, pericardial disease, cardiomyopathies and valvular heart disease.

Computational Analysis of Virtual Echocardiographic Assessment of Functional Mitral Regurgitation for Validation of Proximal Isovelocity Surface Area Methods

BACKGROUND

Mitral regurgitation (MR) quantification by the proximal isovelocity surface area (PISA) method remains challenging. Using computer models, the authors evaluated the accuracy of different PISA methods and quantified their errors.

METHODS

Five functional MR computer models of different geometric and tethering abnormalities were created, validated, and treated as phantom models, from which the reference values were directly obtained. Virtual two-dimensional (2D) PISA and three-dimensional (3D) PISA (both peak and integrated values) were performed on these phantom models. By comparing virtual PISA results with reference values, the accuracy of different PISA methods was evaluated, and their sources of errors were quantified.

RESULTS

Compared with reference values of regurgitant flow rate, excellent correlations were found for true PISA (r = 0.99, bias = 32.3 ± 35.3 mL/sec), 3D PISA (r = 0.97, bias = -24.4 ± 55.5 mL/sec), followed by multiplane 2D hemicylindrical PISA (r = 0.88, bias = -24.1 ± 85.4 mL/sec) and hemiellipsoidal PISA (r = 0.91, bias = -55.7 ± 96.6 mL/sec). Weaker correlations were found for single-plane 2D hemispherical PISA (parasternal long-axis: r = 0.71, bias = -77.6 ± 124.5 mL/sec; apical two-chamber: r = 0.69, bias = -52.0 ± 122.0 mL/sec; apical four-chamber: r = 0.82, bias = -65.5 ± 107.3 mL/sec). For regurgitant volume quantification, integrated PISA was more accurate than peak PISA. The bias of 3D PISA improved from -12.7 ± 7.8 mL (peak PISA) to -2.1 ± 5.3 mL (integrated PISA).

CONCLUSIONS

For functional MR quantification, 2D hemispherical PISA had significant underestimation, multiplane 2D hemiellipsoidal and hemicylindrical PISA showed improved accuracy, and 3D PISA was the most accurate. The PISA method is subject to both systematic underestimation due to the Doppler angle effect and systematic overestimation when regurgitant flow is not perpendicular to PISA contour. Integrated PISA is able to capture dynamic MR and is therefore more accurate than peak PISA. The sum of regurgitant flow rates is the most feasible way to perform integrated PISA.

Multimodality imaging in valvular heart disease: how to use state-of-the-art technology in daily practice

Our understanding of the complexities of valvular heart disease (VHD) has evolved in recent years, primarily because of the increased use of multimodality imaging (MMI). Whilst echocardiography remains the primary imaging technique, the contemporary evaluation of patients with VHD requires comprehensive analysis of the mechanism of valvular dysfunction, accurate quantification of severity, and active exclusion extravalvular consequences. Furthermore, advances in surgical and percutaneous therapies have driven the need for meticulous multimodality imaging to aid in patient and procedural selection. Fundamental decision-making regarding whom, when, and how to treat patients with VHD has become more complex. There has been rapid technological advancement in MMI; many techniques are now available in routine clinical practice, and their integration into has the potential to truly individualize management strategies. This review provides an overview of the current evidence for the use of MMI in VHD, and how various techniques within each modality can be used practically to answer clinical conundrums.

Quantitative assessment of tricuspid regurgitation using right and left ventricular stroke volumes obtained from tomographic equilibrium radionuclide ventriculography

BACKGROUND

Quantitative assessment of valve regurgitation using volumetric method by comparing right and left ventricular stroke volumes is still under investigations.

AIMS

To investigate the accuracy of tomographic equilibrium radionuclide ventriculography (t-ERV) for the quantification of tricuspid regurgitation (TR).

METHODS AND RESULTS

Sixty-one patients (44 men; mean age 59 ± 12 years) who underwent both t-ERV and transthoracic echocardiography (TTE) studies within 2 weeks for right ventricular systolic function assessment were eligible for inclusion. A sub-group of 22 patients underwent both t-ERV and CMR. Patients with mitral/aortic regurgitation by TTE were excluded of the study. TR regurgitant volume (RVol) was calculated using the proximal isovelocity surface area (PISA) method from TTE and the volumetric method (right ventricular stroke volume minus left ventricular stroke volume) from t-ERV. There was a significant correlation between RVol as assess by ERV and by TTE (R = 0.95, P < 0.0001). Intraclass correlation coefficient between TTE and ERV for TR quantification was 0.95 (P < 0.0001). Among patients who underwent CMR, the correlation between RVol obtained by TTE and by t-ERV and CMR were R = 0.81 and R = 0.75, respectively (all P < 0.0001).

CONCLUSION

TR assessment using the t-ERV correlates well with PISA from TTE in patients referred for right ventricular systolic function assessment.

Review: application of current imaging modalities in the management of left-sided valvular heart disease

In terms of valvular heart disease (VHD) imaging, transthoracic echocardiography (TTE) is the preferred first choice because of its widespread availability. Other modalities, such as transesophageal echocardiography, computed tomography and magnetic resonance imaging, have played a supplementary role in diagnosis for severity, deciding the timing/type of treatment, detection of post procedural complications, and prognostic predictions. However, there are few consensuses on how to employ these modalities, as the evidence is not extensive as that for TTE. On the other hand, these imaging modalities also have their own unique strengths. If employed properly, these modalities have the potential to play a more prominent role in clinical decision making. In this review, we focus on the potential, limitations and application of current imaging modalities in the management of left-sided VHD.

Cardiovascular Magnetic Resonance Imaging and Heart Failure

Purpose of Review

The purpose of this review is to summarize the application of cardiac magnetic resonance (CMR) in the diagnostic and prognostic evaluation of patients with heart failure (HF).

Recent Findings

CMR is an important non-invasive imaging modality in the assessment of ventricular volumes and function and in the analysis of myocardial tissue characteristics. The information derived from CMR provides a comprehensive evaluation of HF. Its unique ability of tissue characterization not only helps to reveal the underlying etiologies of HF but also offers incremental prognostic information.

Summary

CMR is a useful non-invasive tool for the diagnosis and assessment of prognosis in patients suffering from heart failure.

Aortic and mitral flow quantification using dynamic valve tracking and machine learning: Prospective study assessing static and dynamic plane repeatability, variability and agreement

Background

Blood flow is a crucial measurement in the assessment of heart valve disease. Time-resolved flow using magnetic resonance imaging (4 D flow MRI) can provide a comprehensive assessment of heart valve hemodynamics but it relies in manual plane analysis. In this study, we aimed to demonstrate the feasibility of automate the detection and tracking of aortic and mitral valve planes to assess blood flow from 4 D flow MRI.

Methods

In this prospective study, a total of n = 106 subjects were enrolled: 19 patients with mitral disease, 65 aortic disease patients and 22 healthy controls. Machine learning was employed to detect aortic and mitral location and motion in a cine three-chamber plane and a perpendicular projection was co-registered to the 4 D flow MRI dataset to quantify flow volume, regurgitant fraction, and a peak velocity. Static and dynamic plane association and agreement were evaluated. Intra- and inter-observer, and scan-rescan reproducibility were also assessed.

Results

Aortic regurgitant fraction was elevated in aortic valve disease patients as compared with controls and mitral valve disease patients (p < 0.05). Similarly, mitral regurgitant fraction was higher in mitral valve patients (p < 0.05). Both aortic and mitral total flow were high in aortic patients. Static and dynamic were good (r > 0.6, p < 0.005) for aortic total flow and peak velocity, and mitral peak velocity and regurgitant fraction. All measurements showed good inter- and intra-observer, and scan-rescan reproducibility.

Conclusion

We demonstrated that aortic and mitral hemodynamics can efficiently be quantified from 4 D flow MRI using assisted valve detection with machine learning.

Quantification of regurgitation in mitral valve prolapse with automated real time echocardiographic 3D proximal isovelocity surface area: multimodality consistency and role of eccentricity index

Three-dimensional transthoracic echocardiography (3D-TTE) provides a semi-automated proximal isovelocity surface area method (3D-PISA) to obtain quantitative parameters. Data assessing regurgitation severity in mitral valve prolapse (MVP) are scarce, so we assessed the 3D-PISA method compared with 2D-PISA and cardiovascular magnetic resonance (CMR) and the role of an eccentricity index. We evaluated the 3D-PISA method for assessing MR in 54 patients with MVP (57 ± 14 years; 42 men; 12 mild/mild-moderate; 12 moderate-severe; and 30 severe MR). Role of an asymmetric (i.e. eccentricity index ≥ 1.25) flow convergence region (FCR) and inter-modality consistency were then assessed. 3D-PISA derived regurgitant volume (RVol) showed a good correlation with 2D-PISA and CMR derived parameters (r = 0.86 and r = 0.81, respectively). The small mean differences with 2D-PISA derived RVol did not reach statistical significance in overall population (5.7 ± 23 ml, 95% CI - 0.6 to 12; p = 0.08) but differed in those with asymmetric 3D-FCR (n = 21; 2D-PISA: 72 ± 36 ml vs. 3D-PISA: 93 ± 47 ml; p = 0.001). RVol mean values were higher using PISA methods (CMR 57 ± 33 ml; 2D-PISA 73 ± 39 ml; and 3D-PISA 79 ± 45 ml) and an overestimation was observed when CMR was used as reference (2D-PISA vs. CMR: mean difference: 15.8 ml [95% CI 10-22, p < 0.001]; and 3D-PISA vs. CMR: 21.5 ml [95% CI 14-29, p < 0.001]). Intra- and inter-observer reliability was excellent (ICC 0.91-0.99), but with numerically lower coefficient of variation for 3D-PISA (8%-10% vs. 2D-PISA: 12%-16%). 3D-PISA method for assessing regurgitation in MVP may enable analogous evaluation compared to standard 2D-PISA, but with overestimation in case of asymmetric FCR or when CMR is used as reference method.

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.

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.