Quantitation of mitral regurgitation with cardiac magnetic resonance imaging: a systematic review

Prospective Quantification of Tricuspid Regurgitation With Echocardiography vs 4D Flow Cardiac Magnetic Resonance

BACKGROUND

Cardiac magnetic resonance (CMR) is a valuable tool in the assessment of valvular disease. However, its utilization in tricuspid regurgitation (TR) evaluation has been limited.

OBJECTIVES

The authors sought to compare TR grading with 4D-CMR and transthoracic echocardiography (TTE).

METHODS

We prospectively recruited patients with ≥ moderate TR on TTE to undergo multiparametric CMR with integrated cardiac function and 4D flow assessments using a 1.5-T scanner (Siemens Somatom Aera). Patients with other severe valvulopathy, end-stage renal disease, or pacemakers were excluded. TR was graded severe on CMR when TR volume ≥45 mL and/or TR fraction ≥50%. The weighted kappa test was used to assess the agreement in overall TR grading on TTE and CMR.

RESULTS

Fifty-two patients were enrolled (mean age 78.5 ± 7.6 years, 53.8% men). The median interval between CMR and TTE was 2 days (Q1-Q3: 1-37 days). The agreement between TTE and CMR-derived TR volume was fair (kappa = 0.28, 95% CI: 0.13-0.45), with only 10 of 31 patients (32%) with ≥ severe TR on TTE meeting severe TR volume criterion on CMR (TR volume ≥45 mL). There was no agreement between TTE and CMR-derived TR fraction (kappa = 0.04, 95% CI: 0.13-0.46), with only 3 of 31 patients (13%) with ≥ severe TR on TTE meeting severe TR criterion on CMR (TR fraction ≥50%).

CONCLUSIONS

Grading of TR was frequently discordant between TTE and 4D magnetic resonance imaging. Further studies are needed to elucidate the clinical impact of concordant/discordant TR grading on multimodality imaging.

Incremental Effect of Mitral Regurgitation on Left Atrial Dysfunction and Atrioventricular Interaction in Hypertensive Patients by MRI

BACKGROUND

Mitral regurgitation may occur when hypertension causes left ventricular (LV) and left atrial (LA) remodeling. However, its role in LA function in hypertensive patients remains unclear.

PURPOSE

To explore how mitral regurgitation affects LA function in hypertension and to investigate atrioventricular interaction in hypertensive patients with mitral regurgitation.

STUDY TYPE

Retrospective.

POPULATION

A total of 193 hypertensive cases and 64 controls.

FIELD STRENGTH/SEQUENCE

A 3.0 T/balanced steady-state free precession.

ASSESSMENT

LA volume (LAV), LA strain (reservoir, conduit, and active), LA ejection fraction, and LV strain (global peak longitudinal [GLS], circumferential [GCS], and radial strain [GRS]) were evaluated and compared among groups. Regurgitant fraction (RF) was evaluated in regurgitation patients and used to subdivide patients into mild (RF: 0%-30%), moderate (RF: 30%-50%), and severe (RF: >50%) regurgitation categories.

STATISTICAL TESTS

One-way analysis of variance, Spearman and Pearson's correlation coefficients (r), and multivariable linear regression analysis. A P value <0.05 was considered statistically significant.

RESULTS

Hypertensive patients without mitral regurgitation showed significantly impaired LA reservoir and conduit functions and significantly decreased LV GLS but preserved pump function and LAV compared to controls (P = 0.193-1.0). Hypertensive cases with mild regurgitation (N = 22) had significantly enlarged LAV and further reduced LA reservoir function, while the group with moderate regurgitation (N = 20) showed significantly reduced LA pump function, further impaired conduit function, and significantly reduced LV strain. The severe regurgitation (N = 13) group demonstrated significantly more severely impaired LA and LV functions and LAV enlargement. Multivariable linear regression showed that regurgitation degree, GRS, GCS, and GLS were independently correlated with the LA reservoir, conduit, and active strain in hypertensive patients with mitral regurgitation.

DATA CONCLUSION

Mitral regurgitation may exacerbate LA and LV impairment in hypertension. Regurgitation degree, LV GRS, GCS, and GLS were independent determinants of the LA strain in hypertensive patients with mitral regurgitation, which demonstrated atrioventricular interaction.

EVIDENCE LEVEL

4.

TECHNICAL EFFICACY

Stage 3.

Mitral and Tricuspid Valve Disease in Athletes

Observing mitral or tricuspid valve disease in an athlete raises many considerations for the clinician. Initially, the etiology must be clarified, with causes differing depending on whether the athlete is young or a master. Notably, vigorous training in competitive athletes leads to a constellation of structural and functional adaptations involving cardiac chambers and atrioventricular valve systems. In addition, a proper evaluation of the athlete with valve disease is necessary to evaluate the eligibility for competitive sports and identify those requiring more follow-up. Indeed, some valve pathologies are associated with an increased risk of severe arrhythmias and potentially sudden cardiac death. Traditional and advanced imaging modalities help clarify clinical doubts, allowing essential information about the athlete's physiology and differentiating between primary valve diseases from those secondary to training-related cardiac adaptations. Remarkably, another application of multimodality imaging is evaluating athletes with valve diseases during exercise to reproduce the sport setting and better characterize the etiology and valve defect mechanism. This review aims to analyze the possible causes of atrioventricular valve diseases in athletes, focusing primarily on imaging applications in diagnosis and risk stratification.

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.

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.

Additive effects of mitral regurgitation on left ventricular strain in essential hypertensive patients as evaluated by cardiac magnetic resonance feature tracking

Objectives

Hypertension is one of the leading risk factors for cardiovascular disease. Mitral regurgitation (MR) is a heart valve disease commonly seen in hypertensive cases. This study aims to assess the effect of MR on left ventricle (LV) strain impairment among essential hypertensive cases and determine factors that independently impact the global peak strain of the LV.

Materials and methods

We enrolled 184 essential hypertensive patients, of which 53 were patients with MR [HTN (MR +) group] and 131 were without MR [HTN (MR−) group]. Another group of 61 age-and gender-matched controls was also included in the study. All participants had received cardiac magnetic resonance examination. The HTN (MR +) group was classified into three subsets based on regurgitation fraction, comprising mild MR (n = 22), moderate MR (n = 19), and severe MR (n = 12). We compared the LV function and strain parameters across different groups. Moreover, we performed multivariate linear regression to determine the independent factors affecting LV global radial peak strain (GRS), circumferential peak strain (GCS), and global longitudinal peak strain (GLS).

Results

HTN (MR−) cases exhibited markedly impaired GLS and peak diastolic strain rate (PDSR) but preserved LV ejection fraction (LVEF) compared to the controls. However, HTN (MR +) patients showed a decrease in LVEF and further deteriorated GRS, GCS, GLS, PDSR, and the peak systolic strain rate (PSSR) compared to the HTN (MR−) group and controls. With increasing degrees of regurgitation, the LV strain parameters were gradually reduced in HTN (MR +) patients. Even the mild MR group showed impaired GCS, GLS, PDSR, and PSSR compared to the HTN (MR−) group. Multiple regression analyses indicated that the degree of regurgitation was independently associated with GRS (β = -0.348), GCS (β = -0.339), and GLS (β = -0.344) in HTN (MR +) patients.

Conclusion

GLS was significantly impaired in HTN (MR−) patients. MR may further exacerbate the deterioration of LV strain among essential hypertensive cases. Besides, the degree of regurgitation was independently correlated with GRS, GCS, and GLS in HTN (MR +) patients.

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.

Atrioventricular coupling and left atrial abnormality in type 2 diabetes mellitus with functional mitral regurgitation patients verified by cardiac magnetic resonance imaging

BACKGROUND

Functional mitral regurgitation (FMR) in type 2 diabetes mellitus (T2DM) patients induced by left ventricular (LV) enlargement and mitral valve abnormality may aggravated the impairment in left atrial (LA) compliance. Thus, this study aimed to depict how FMR and LV dysfunction affect LA compliance in T2DM patients with FMR.

MATERIALS AND METHODS

A total of 148 patients with T2DM and 49 age- and sex-matched normal controls underwent cardiac magnetic resonance examination. LA longitudinal strain and LA and LV functional indices were compared among controls and different T2DM patients. The multivariate analysis was used to identify the independent indicators of LA longitudinal strain.

RESULTS

T2DM Patients without FMR had a lower total LA empty fraction (LAEF) compared with the controls (all P < 0.05). T2DM patients with mild and moderate FMR showed increased LA volume (LAV) and LV volume while decreased LAEF, LA strain, and LV ejection fraction (P < 0.05). T2DM patients with severe FMR showed markedly increased LAV and LV volume while decreased LAEF, LA strain, and LVEF (P < 0.05). In T2DM patients with FMR, reservoir strain (εs) was independently correlated with LV end-diastolic volume (LVEDV) (β = - 0.334) and regurgitation degree (β = - 0.256). The passive strain (εe) was independently correlated with regurgitation degree (β = - 0.297), whereas the active strain (εa) was independently correlated with LVESV (β = - 0.352) and glycated haemoglobin (β = - 0.279).

CONCLUSION

FMR may aggravate LA and LV dysfunction in T2DM patients. Regurgitation degree was an independent determinant of the εs and the εe, LVEDV was an independent determinant of the εs, and LVESV was an independent determinant of the εa in T2DM patients with FMR.

Pre-operative Considerations in Adult Mucopolysaccharidosis Patients Planned for Cardiac Intervention

Mucopolysaccharidoses (MPS) are rare lysosomal storage diseases characterized by multiorgan involvement and shortened longevity. Due to advances in therapies such as enzyme replacement therapy and haematopoietic stem cell therapy, life expectancy has increased posing newer challenges to patients and health professionals. One such challenge is cardiovascular manifestations of MPS, which can be life limiting and cause reduction in quality of life. Any cardiovascular intervention mandates comprehensive, multi-systemic work-up by specialist teams to optimize outcome. We highlight the importance of multidisciplinary evaluation of adult MPS patients requiring cardiovascular intervention. Clinical assessments and investigations are discussed, with a focus on the cardiac, anesthetic, airway, respiratory, radiological and psychosocial factors.

Effect of Mitral Regurgitation on Left Ventricular Deformation in Myocardial Infarction Patients: Evaluation by Cardiac Magnetic Resonance Imaging

BACKGROUND

Mitral regurgitation (MR) is a comorbidity of myocardial infarction (MI), which may promote the incidence of adverse cardiovascular clinical events. However, it is not yet completely understood how MR in MI patients is associated with impaired myocardial deformation.

PURPOSE

To determine the damaging myocardium effects of MR in MI patients in terms of the global peak strain (PS) and left ventricular (LV) function, and evaluate the independent risk factors impacting LV deformation after MI.

STUDY TYPE

Retrospective.

POPULATION

One hundred eighty-six MI patients (17.7% female) and 84 normal control subjects (27.4% female).

FIELD STRENGTH/SEQUENCE

3.0T; late gadolinium enhancement sequence, balanced steady-state free precession.

ASSESSMENT

LV function and LV global PS (global radial peak strain [GRPS]; global circumferential peak strain [GCPS]; and global longitudinal peak strain [GLPS]) were compared among normal controls, MI without MR (MR-) and MI with MR (MR+, mild, moderate, severe) patients.

STATISTICAL TESTS

One-way analysis of variance (ANOVA) test, Mann-Whitney U test, Kruskal-Wallis test, and multiple linear regressions were used. A P value <0.05 indicated statistically significant difference (two-tailed).

RESULTS

The MI (MR+) patients showed significantly lower LV global PS than both MI (MR-) and control groups in three directions (GRPS 16.66 ± 7.43%; GCPS -11.27 ± 4.27%; GLPS -7.75 ± 3.44%), and significantly higher LV end-systolic (128.85 [87.91, 188.01] mL) and end-diastolic volumes (210.29 [164.07, 264.00] mL) and significantly lower LV ejection fraction (38.23 ± 13.02%). Multiple regression analysis demonstrated that MR was independently associated with LV GCPS (β = -0.268) and GLPS (β = -0.320). LV infarct size was an independent indicator of LV GRPS (β = -0.215) and GCPS (β = -0.222). LV end-diastolic volume was an independent indicator of LV GRPS (β = -0.518), GCPS (β = -0.503), and GLPS (β = -0.331).

DATA CONCLUSION

MR may further exacerbate the reduction of LV global peak strains and function. The MR, infarct size, and LV end-diastolic volume can be used as independent association indicators for LV global PS in MI (MR+) patients.

LEVEL OF EVIDENCE

4 Technical Efficacy Stage: 2 TOC Category: Chest.

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.

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.

7-Tesla Functional Cardiovascular MR Using Vectorcardiographic Triggering-Overcoming the Magnetohydrodynamic Effect

Objective: Ultra-high-field B0 ≥ 7 tesla (7T) cardiovascular magnetic resonance (CMR) offers increased resolution. However, electrocardiogram (ECG) gating is impacted by the magneto-hydrodynamic effect distorting the ECG trace. We explored the technical feasibility of a 7T magnetic resonance scanner using an ECG trigger learning algorithm to quantitatively assess cardiac volumes and vascular flow. Methods: 7T scans were performed on 10 healthy volunteers on a whole-body research MRI MR scanner (Siemens Healthineers, Erlangen, Germany) with 8 channel Tx/32 channels Rx cardiac coils (MRI Tools GmbH, Berlin, Germany). Vectorcardiogram ECG was performed using a learning phase outside of the magnetic field, with a trigger algorithm overcoming severe ECG signal distortions. Vectorcardiograms were quantitatively analyzed for false negative and false positive events. Cine CMR was performed after 3rd-order B₀ shimming using a high-resolution breath-held ECG-retro-gated segmented spoiled gradient echo, and 2D phase contrast flow imaging. Artefacts were assessed using a semi-quantitative scale. Results: 7T CMR scans were acquired in all patients (100%) using the vectorcardiogram learning method. 3,142 R-waves were quantitatively analyzed, yielding sensitivity of 97.6% and specificity of 98.7%. Mean image quality score was 0.9, sufficient to quantitate both cardiac volumes, ejection fraction, and aortic and pulmonary blood flow. Mean left ventricular ejection fraction was 56.4%, right ventricular ejection fraction was 51.4%. Conclusion: Reliable cardiac ECG triggering is feasible in healthy volunteers at 7T utilizing a state-of-the-art three-lead trigger device despite signal distortion from the magnetohydrodynamic effect. This provides sufficient image quality for quantitative analysis. Other ultra-high-field imaging applications such as human brain functional MRI with physiologic noise correction may benefit from this method of ECG triggering.

Aggravation of functional mitral regurgitation on left ventricle stiffness in type 2 diabetes mellitus patients evaluated by CMR tissue tracking

BACKGROUND

Functional mitral regurgitation (FMR) is one of the most common heart valve diseases in diabetes and may increase left ventricular (LV) preload and aggravate myocardial stiffness. This study aimed to investigate the aggravation of FMR on the deterioration of LV strain in type 2 diabetes mellitus (T2DM) patients and explore the independent indicators of LV peak strain (PS).

MATERIALS AND METHODS

In total, 157 T2DM patients (59 patients with and 98 without FMR) and 52 age- and sex-matched healthy control volunteers were included and underwent cardiac magnetic resonance examination. T2DM with FMR patients were divided into T2DM patients with mild (n = 21), moderate (n = 19) and severe (n = 19) regurgitation. LV function and global strain parameters were compared among groups. Multivariate analysis was used to identify the independent indicators of LV PS.

RESULTS

The T2DM with FMR had lower LV strain parameters in radial, circumferential and longitudinal direction than both the normal and the T2DM without FMR (all P < 0.05). The mild had mainly decreased peak diastolic strain rate (PDSR) compared to the normal. The moderate had decreased peak systolic strain rate (PSSR) compared to the normal and PDSR compared to the mild and the normal. The severe FMR group had decreased PDSR and PSSR compared to the mild and the normal (all P < 0.05). Multiple linear regression showed that the regurgitation degree was independent associated with radial (β = - 0.272), circumferential (β = - 0.412) and longitudinal (β = - 0.347) PS; the months with diabetes was independently associated with radial (β = - 0.299) and longitudinal (β = - 0.347) PS in T2DM with FMR.

CONCLUSION

FMR may aggravate the deterioration of LV stiffness in T2DM patients, resulting in decline of LV strain and function. The regurgitation degree and months with diabetes were independently correlated with LV global PS in T2DM with FMR.

Guide to functional mitral regurgitation: a contemporary review

Functional mitral regurgitation (FMR) occurs in the absence of organic mitral valve (MV) disease and is a result of LV dysfunction due to ischemic vs. non ischemic etiologies. The prevalence of FMR is increasing, as 2.0-2.5 million people in the USA were diagnosed with FMR in 2000-and this number is expected to double to 4 million by 2030. FMR tends to develop in a significant number of patients after myocardial infarction (MI) and many develop heart failure (HF) subsequently with mortality rates ranging from 15-40% at 1 year. Therefore, there has been much interest and effort to develop optimized methods for quantifying and classifying the severity of FMR, as well as developing effective therapeutic interventions to improve outcomes in patients with significant FMR. Echocardiogram is typically the primary diagnostic method of assessment, however, there have been various technological advances including cardiac CT and cardiac MRI that can better guide quantification and management of this disease. Management of this disease is mostly aimed at optimizing left ventricular (LV) remodeling with surgical and transcatheter management gaining more popularity with recent times. The purpose of this paper is to provide a comprehensive review of the current evaluation methods and interventional strategies for FMR.

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.

Impact of Myocardial Scar on Prognostic Implication of Secondary Mitral Regurgitation in Heart Failure

OBJECTIVES

The objective of the present study was to use cardiovascular magnetic resonance (CMR) to examine the natural history of secondary MR severity and the implication of left ventricular (LV) scar on its prognostic significance.

BACKGROUND

There is a need for further understanding of the prognostic implication of secondary mitral regurgitation (MR) given the heterogeneous findings of the 2 recent randomized trials on percutaneous mitral intervention in patients with secondary MR.

METHODS

Patients with heart failure were enrolled into a prospective observational registry between 2008 and 2019. Outcomes were a composite of all-cause death, heart transplantation, or LV assist device implantation at follow-up. CMR was used to quantify the mitral regurgitation volume and mitral regurgitation fraction (MRF) along with scar burden utilizing late gadolinium enhancement. Patients were categorized into 4 subgroups based on presence and tertiles of scar extent: no scar, limited scar (scar burden 1% to 4%), intermediate scar (scar burden 5% to 20%), and extensive scar (scar burden >20%).

RESULTS

Among patients (n = 441) included in the study (age 59 ± 14 years, 43% with ischemic etiology), 85 (19%) experienced an adverse event. MRF ≥30% was associated with increased risk of events among the study group (hazard ratio: 1.74; 95% confidence interval: 1.10 to 2.76; p = 0.02). When stratified by presence or absence of scar, MRF ≥30% was associated with events only among patients with scar (hazard ratio: 1.67; 95% confidence interval: 1.02 to 2.76; p = 0.04) but not among patients without scar. On further classification of patients with scar, the prognostic significance of secondary MR was observed primarily among patients with intermediate scar burden.

CONCLUSIONS

The natural history of secondary MR is complex, and outcomes are affected by severity of MR and vary depending upon the extent of scar. (DeBakey Cardiovascular Magnetic Resonance Study [DEBAKEY-CMR]; NCT04281823).

Cardiovascular imaging modalities in the diagnosis and management of rheumatic heart disease

Rheumatic heart disease (RHD) is prevalent in sub-Saharan Africa, where the capacity for diagnosis and evaluation of disease severity and complications is not always optimal. While the medical history and physical examination are important in the assessment of patients suspected to have RHD, cardiovascular imaging techniques are useful for confirmation of the diagnosis. Echocardiography is the workhorse modality for initial evaluation and diagnosis of RHD. Cardiovascular magnetic resonance is complementary and may provide additive information, including tissue characteristics, where echocardiography is inadequate or non-diagnostic. There is emerging evidence on the role of computed tomography, particularly following valve replacement surgery, in the monitoring and management of RHD. This article summarises the techniques used in imaging RHD patients, considers the evidence base for their utility, discusses their limitations and recognises the clinical contexts in which indications and imaging with various modalities are expanding.

Proportionate or disproportionate secondary mitral regurgitation: how to untangle the Gordian knot?

Recent randomised percutaneous mitral intervention trials in patients with heart failure with secondary mitral regurgitation (SMR) have yielded contrasting results. A 'relative load' or 'proportionality' conceptual framework for SMR has been proposed to partly explain the disparate results. The rationale behind the framework is that SMR depends on the left ventricular dimension and not vice versa. In this review, we provide an in-depth analysis of the proportionality parameters used in this framework and also discuss the regurgitant fraction. We also consider haemodynamic observations in SMR that may affect the interpretation and comparisons among proportionality parameters. The conclusion is that the proportionality concept remains hypothetical and requires prospective validation before envisaging its use at individual patient level for risk stratification or therapeutic decision-making.

Direct measurement of atrioventricular valve regurgitant jets using 4D flow cardiovascular magnetic resonance is accurate and reliable for children with congenital heart disease: a retrospective cohort study

BACKGROUND

3D-time resolved flow (4DF) cardiovascular magnetic resonance (CMR) with retrospective analysis of atrioventricular valve regurgitation (AVVR) allows for internal validation by multiple direct and indirect methods. Limited data exist on direct measurement of AVVR by 4DF CMR in pediatric congenital heart disease (CHD). We aimed to validate direct measurement of the AVVR jet as accurate and reliable compared to the volumetric method (clinical standard by 2D CMR) and as a superior method of internal validation than the annular inflow method.

METHODS

We identified 44 consecutive patients with diverse CHD referred for evaluation of AVVR by CMR. 1.5 T or 3 T scanners, intravenous contrast, and a combination of parallel imaging and compressed sensing were used. Four methods of measuring AVVR volume (RVol) were used: volumetric method (VOL; the clinical standard) = stroke volume by 2D balanced steady-state free precession - semilunar valve forward flow (SLFF); annular inflow method (AIM) = atrioventricular valve forward flow [AVFF] - semilunar valve net flow (SLNF); and direct measurement (JET). AVFF was measured using static and retrospective valve tracking planes. SLFF, SLNF, AVFF, and JET were measured by 4DF phase contrast. Regurgitant fraction was calculated as [RVol/(RVol+SLNF)]× 100. Statistical methods included Spearman, Wilcoxon rank sum test/Student paired t-test, Bland Altman analysis, and intra-class coefficient (ICC), where appropriate.

RESULTS

Regurgitant fraction by JET strongly correlated with the indirect methods (VOL and AIM) (ρ = 0.73-0.80, p < 0.001) and was similar to VOL with a median difference (interquartile range) of - 1.5% (- 8.3-7.2%; p = 0.624). VOL had weaker correlations with AIM and JET (ρ = 0.69-0.73, p < 0.001). AIM underestimated RF by 3.6-6.9% compared to VOL and JET, p < 0.03. Intra- and inter- observer reliability were excellent for all methods (ICC 0.94-0.99). The mean (±standard deviation) inter-observer difference for VOL was 2.4% (±5.1%), p < 0.05.

CONCLUSIONS

In a diverse cohort of pediatric CHD, measurement of AVVR using JET is accurate and reliable to VOL and is a superior method of internal validation compared to AIM. This study supports use of 4DF CMR for measurement of AVVR, obviating need for expert prospective prescription during image acquisition by 2D CMR.

A Comprehensive Engineering Analysis of Left Heart Dynamics After MitraClip in a Functional Mitral Regurgitation Patient

Percutaneous edge-to-edge mitral valve (MV) repair using MitraClip has been recently established as a treatment option for patients with heart failure and functional mitral regurgitation (MR), which significantly expands the number of patients that can be treated with this device. This study aimed to quantify the morphologic, hemodynamic and structural changes, and evaluate the biomechanical interaction between the MitraClip and the left heart (LH) complex of a heart failure patient with functional MR using a fluid-structure interaction (FSI) modeling framework. MitraClip implantation using lateral, central and double clip positions, as well as combined annuloplasty procedures were simulated in a patient-specific LH model that integrates detailed anatomic structures, incorporates age- and gender-matched non-linear elastic material properties, and accounts for mitral chordae tethering. Our results showed that antero-posterior distance, mitral annulus spherecity index, anatomic regurgitant orifice area, and anatomic opening orifice area decreased by up to 28, 39, 52, and 71%, respectively, when compared to the pre-clip model. MitraClip implantation immediately decreased the MR severity and improved the hemodynamic profile, but imposed a non-physiologic configuration and loading on the mitral apparatus, with anterior and posterior leaflet stress significantly increasing up to 210 and 145% during diastole, respectively. For this patient case, while implanting a combined central clip and ring resulted in the highest reduction in the regurgitant volume (46%), this configuration also led to mitral stenosis. Patient-specific computer simulations as used here can be a powerful tool to examine the complex device-host biomechanical interaction, and may be useful to guide device positioning for potential favorable clinical outcomes.

The Impact of Self-Expandable Transcatheter Aortic Valve Replacement on Concomitant Functional Mitral Regurgitation: A Comprehensive Engineering Analysis

Background

Mitral regurgitation (MR) is present in a large proportion of patients who undergo transcatheter aortic valve replacement (TAVR). However, existing clinical data on the impact of TAVR on early post-procedural MR severity are contradictory. Using a comprehensive computational engineering methodology, this study aimed to evaluate quantitatively the structural and hemodynamic impact of TAVR on aortic-mitral continuity and MR severity in a rigorously developed and validated patient-specific left heart (LH) computer model with aortic stenosis and concomitant functional MR.

Methods

TAVR procedure was virtually simulated using a self-expandable valve (SEV) at three implantation heights. Pre- and post-TAVR LH dynamics as well as intra-operative biomechanics were analyzed.

Results

No significant differences in early MR improvement (<10%) were noted at the three implantation depths when compared to the pre-TAVR state. The high deployment model resulted in the highest stress in the native aortic leaflets, lowest stent-tissue contact force, highest aortic-mitral angle, and highest MR reduction for this patient case. When comparing SEV vs. balloon-expandable valve (BEV) performance at an optimal implantation height, the SEV gave a higher regurgitant volume ⋅ than the pre-TAVR model (40.49 vs 37.59 ml), while the BEV model gave the lowest regurgitant volume (33.84 vs 37.59 ml).

Conclusions

Contact force, aortic-mitral angle, and valve annuli compression were identified as possible mechanistic parameters that may suggest avenues for acute MR improvement. Albeit a single patient parametric study, it is our hope that such detailed engineering analysis could shed some light into the underlying biomechanical mechanisms of TAVR impact on MR.

4D flow vs. 2D cardiac MRI for the evaluation of pulmonary regurgitation and ventricular volume in repaired tetralogy of Fallot: a retrospective case control study

Lengthy exams and breath-holding limit the use of pediatric cardiac MRI (CMR). 3D time-resolved flow MRI (4DF) is a free-breathing, single-sequence exam that obtains magnitude (anatomic) and phase contrast (PC) data. We compare the accuracy of gadobenate dimeglumine-enhanced 4DF on a 1.5 T magnet to 2D CMR in children with repaired tetralogy of Fallot (rTOF) to measure pulmonary net flow (PNF) as a reflection of pulmonary regurgitation, forward flow (FF) and ventricular volumetry. Thirty-four consecutive cases were included. 2D PCs were obtained at the valve level. Using 4DF, we measured PNF at the valve and at the main and branch pulmonary arteries. PNF measured at the valve by 4DF demonstrated the strongest correlation (r = 0.87, p < 0.001) and lowest mean difference (3.5 ± 9.4 mL/beat) to aortic net flow (ANF). Semilunar FF and stroke volume of the respective ventricle demonstrated moderate-strong correlation by 4DF (r = 0.66-0.81, p < 0.001) and strong correlation by 2D (r = 0.81-0.84, p < 0.001) with similar correlations and mean differences between techniques (p > 0.05). Ventricular volumes correlated strongly between 2D and 4DF (r = 0.75-0.96, p < 0.001), though 4DF overestimated right ventricle volumes by 11.8-19.2 mL/beat. Inter-rater reliability was excellent for 2D and 4DF volumetry (ICC = 0.91-0.99). Ejection fraction moderately correlated (r = 0.60-0.75, p < 0.001) with better reliability by 4DF (ICC: 0.80-0.85) than 2D (ICC: 0.69-0.89). 4DF exams were shorter than 2D (9 vs. 71 min, p < 0.001). 4DF provides highly reproducible and accurate measurements of flow with slight overestimation of RV volumes compared to 2D in pediatric rTOF. 4DF offers important advantages in this population with long-term monitoring needs.

Prognostic Impact of Ischemic Mitral Regurgitation Severity and Myocardial Infarct Quantification by Cardiovascular Magnetic Resonance

OBJECTIVES

This study sought to evaluate the role of cardiac magnetic resonance (CMR) for the quantification of ischemic mitral regurgitation (IMR) and myocardial infarct size (MIS) in patients with ischemic cardiomyopathy (ICM). This study also sought to explore the interaction between IMR severity and MIS and its association with outcomes in patients with ICM.

BACKGROUND

IMR occurs secondary to a disease of the left ventricle and is associated with poor outcomes. The role of CMR for the evaluation and risk stratification of patients with ICM and IMR remains uncertain.

METHODS

Consecutive patients with ICM who underwent baseline CMR were included. MIS was quantified on late gadolinium enhancement imaging as the proportion of left ventricular mass. IMR was quantified with CMR by calculating the mitral regurgitant fraction (MRFraction). Cox proportional hazards models were built to assess the association of IMR and MIS quantification with the combined endpoint of all-cause death or heart transplant.

RESULTS

We evaluated 578 patients (mean age: 62 ± 11 years, 76% males). The mean left ventricular ejection fraction was 25 ± 11%, with an MIS of 24 ± 16% and MRFraction of 18 ± 17%. Over a median follow-up time of 4.9 years, 198 (34%) patients experienced death or cardiac transplant. On multivariable analysis, after comprehensive medical risk score, subsequent revascularization, implantable cardioverter-defibrillator insertion, and surgical mitral valve intervention were controlled for, the interaction of IMR severity and MIS emerged as a powerful predictor of adverse outcomes (p = 0.008). For patients with significant IMR (MRFraction: ≥35%), the hazard ratio comparing moderate MIS (15% to 29%) versus small MIS (<15%) was 1.51 (0.57 to 3.98), and the hazard ratio comparing large MIS (≥30%) versus small MIS was 5.41 (2.34 to 12.7).

CONCLUSIONS

Risk associated with IMR is more comprehensively described as an interaction between IMR severity and MIS. Further studies in patients IMR using comprehensive CMR evaluation are needed to verify whether this approach can improve patient selection and procedural outcomes to address IMR.

The Average Pixel Intensity Method and Outcome of Mitral Regurgitation in Mitral Valve Prolapse

BACKGROUND

Mitral regurgitation (MR) is a frequent consequence of mitral valve prolapse (MVP). However, the echocardiographic grading of MR is challenging, and the recommended grading parameters have several limitations. The authors developed a novel echocardiographic parameter to grade MR, the average pixel intensity (API) method, on the basis of pixel intensity analysis of the continuous-wave Doppler signal.

METHODS

Transthoracic echocardiography was performed prospectively in consecutive patients with MVP (N = 149). MR was quantitatively assessed using the API method, vena contracta width, effective regurgitant orifice area, and regurgitant volume. The primary clinical events were cardiovascular mortality, mitral valve surgery, percutaneous mitral intervention, and heart failure hospitalization.

RESULTS

The API method was feasible in 90% of all patients with MVP, which was significantly higher than vena contracta width, effective regurgitant orifice area, and regurgitant volume. During a median follow-up period of 17 months, 44 patients (32%) had major adverse cardiac events, and the majority of events occurred in the holosystolic MVP subgroup. The degree of MR severity by the API method was highly significant for the prediction of events. An API cutoff of 111 arbitrary units was defined as "severe" MR due to MVP, with overall superior sensitivity and specificity compared with cutoffs for established MR grading parameters. In patients who did not have major adverse cardiac events during the follow-up period (n = 92), no significant changes in measures of MR severity were found on follow-up echocardiography.

CONCLUSIONS

The API method is predictive of clinical events and outcomes in MR due to MVP. Therefore, the API method may be considered for grading the severity of MR due to MVP in clinical practice.

The impact of balloon-expandable transcatheter aortic valve replacement on concomitant mitral regurgitation: a comprehensive computational analysis

The aortic and mitral valves function in a reciprocal interdependent fashion. However, the impact of transcatheter aortic valve replacement (TAVR) on the aortic-mitral continuity and severity of mitral regurgitation (MR) are poorly understood. In this study, a comprehensive engineering analysis was performed to investigate the impact of TAVR on MR severity and left heart dynamics in a retrospective patient case who harbours bicuspid aortic valve stenosis and concomitant functional MR. The TAVR procedure was computer simulated using a balloon-expandable valve, and the impact of three implantation heights on aortic-mitral coupling, MR severity and device performance were analysed. The accuracy and predictability of the computer modelling framework were validated with pre- and post-operative echo data. The highest deployment model resulted in higher stresses in the native leaflets, contact radial force and stent recoil, while the midway implantation model gave better haemodynamic performance and MR reduction in this patient case. Although the regurgitant volume decreased (less than 10%) for the three deployment configurations, no significant differences in MR severity improvement and mitral leaflet tethering were found. Acute improvement in MR was (i) due to the mechanical compression of the stent against the aortic-mitral curtain, (ii) due to an immediate drop in the ventricular pressure and transmitral pressure gradient. Albeit a single real clinical case, it is our hope that such detailed engineering computational analysis could shed light on the underlying biomechanical mechanisms of TAVR impact on MR.

Increased levels of sST2 in patients with mitral annulus disjunction and ventricular arrhythmias

Objective

Displacement of the mitral valve, mitral annulus disjunction (MAD), is described as a possible aetiology of sudden cardiac death. Stress-induced fibrosis in the mitral valve apparatus has been suggested as the underlying mechanism. We aimed to explore the association between stretch-related and fibrosis-related biomarkers and ventricular arrhythmias in MAD. We hypothesised that soluble suppression of tumourigenicity-2 (sST2) and transforming growth factor-β1 (TGFβ1) are markers of ventricular arrhythmias in patients with MAD.

Methods

We included patients with ≥1 mm MAD on cardiac MRI. We assessed left ventricular ejection fraction (LVEF) and fibrosis by late gadolinium enhancement (LGE). The occurrence of ventricular arrhythmia, defined as aborted cardiac arrest, sustained or non-sustained ventricular tachycardia, was retrospectively assessed. We assessed circulating sST2 and TGFβ1 levels.

Results

We included 72 patients with MAD, of which 22 (31%) had ventricular arrhythmias. Patients with ventricular arrhythmias had lower LVEF (60 % (±6) vs 63% (±6), p = 0.04), more frequently papillary muscle fibrosis (14 (64%) vs 10 (20%), p < 0.001) and higher sST2 levels (31.6 ± 10.1 ng/mL vs 25.3 ± 9.2 ng/mL, p = 0.01) compared with those without, while TGFβ1 levels did not differ (p = 0.29). Combining sST2 level, LVEF and papillary muscle fibrosis optimally detected individuals with arrhythmia (area under the curve 0.82, 95% CI 0.73 to 0.92) and improved the risk model (p < 0.05) compared with single parameters.

Conclusion

Circulating sST2 levels were higher in patients with MAD and ventricular arrhythmias compared with arrhythmia-free patients. Combining sST2, LVEF and LGE assessment improved risk stratification in patients with MAD.

4D flow MRI quantification of mitral and tricuspid regurgitation: Reproducibility and consistency relative to conventional MRI

BACKGROUND

In patients with mitral or tricuspid valve regurgitation, evaluation of regurgitant severity is essential for determining the need for surgery. While transthoracic echocardiography is widely accessible, it has limited reproducibility for grading inlet valve regurgitation. Multiplanar cardiac MRI is the quantitative standard but requires specialized local expertise, and is thus not widely available. Volumetric 4D flow MRI has potential for quantitatively grading the severity of inlet valve regurgitation in adult patients.

PURPOSE

To evaluate the accuracy and reproducibility of volumetric 4D flow MRI for quantification of inlet valvular regurgitation compared to conventional multiplanar MRI, which may simplify and improve accessibility of cardiac MRI.

STUDY TYPE

This retrospective, HIPAA-compliant imaging-based comparison study was conducted at a single institution.

SUBJECTS

Twenty-one patients who underwent concurrent multiplanar and 4D flow cardiac MRI between April 2015 and January 2017.

FIELD STRENGTH/SEQUENCES

3T; steady-state free-precession (SSFP), 2D phase contrast (2D-PC), and postcontrast 4D flow.

ASSESSMENT

We evaluated the intertechnique (4D flow vs. 2D-PC), intermethod (direct vs. indirect measurement), interobserver and intraobserver reproducibility of measurements of regurgitant flow volume (RFV), fraction (RF), and volume (RVol).

STATISTICAL TESTS

Statistical analysis included Pearson correlation, Bland-Altman statistics, and intraclass correlation coefficients.

RESULTS

There was high concordance between 4D flow and multiplanar MRI, whether using direct or indirect methods of quantifying regurgitation (r = 0.813-0.985). Direct interrogation of the regurgitant jet with 4D flow showed high intraobserver consistency (r = 0.976-0.999) and interobserver consistency (r = 0.861-0.992), and correlated well with traditional indirect measurements obtained as the difference between stroke volume and forward outlet valve flow.

DATA CONCLUSION

4D flow MRI provides highly reproducible measurements of mitral and tricuspid regurgitant volume, and may be used in place of conventional multiplanar MRI.

LEVEL OF EVIDENCE

4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:1147-1158.

CMR quantitation of change in mitral regurgitation following transcatheter aortic valve replacement (TAVR): impact on left ventricular reverse remodeling and outcome

Current echocardiographic data reporting the impact of concomitant mitral regurgitation (MR) on outcome in patients who undergo transcatheter aortic valve replacement (TAVR) are conflicting. Using cardiovascular magnetic resonance (CMR) imaging, this study aimed to assess the impact of MR severity on cardiac reverse remodeling and patient outcome. 85 patients undergoing TAVR with CMR pre- and 6 m post-TAVR were evaluated. The CMR protocol included cines for left (LV) and right ventricular (RV) volumes, flow assessment, and myocardial scar assessment by late gadolinium enhancement (LGE). Patients were dichotomised according to CMR severity of MR fraction at baseline (‘non-significant’ vs ‘significant’) and followed up for a median duration of 3 years. Forty-two (49%) patients had ‘significant MR’ at baseline; they had similar LV and RV size and function compared to the ‘non-significant MR’ group but had greater LV mass at baseline. In those with significant MR at baseline, 77% (n = 32) had a reduction in MR post-TAVR, moving them into the ‘non-significant’ category at 6-months, with an overall reduction in MR fraction from 34 to 17% (p < 0.001). Improvement in MR was not associated with more favourable cardiac reverse remodeling when compared with the ‘non-improvers’. Significant MR at baseline was not associated with increased mortality at follow-up. Significant MR is common in patients undergoing TAVR and improves in the majority post-procedure. Improvement in MR was not associated with more favourable LV reverse remodeling and baseline MR severity was not associated with mortality.

Multimodality Imaging of the Tricuspid Valve for Assessment and Guidance of Transcatheter Repair

The tricuspid valve is a highly complex structure, with variability in the number of leaflets and scallops. The mechanism of regurgitation is multifactorial in etiology, a mix of functional and degenerative tricuspid regurgitation. Iatrogenic tricuspid regurgitation is becoming more common secondary to pacemaker wire impingement of leaflet function and coaptation. Echocardiographic imaging of the tricuspid valve is particularly challenging given its anatomic location and other interfering structures, including pacemaker wires. Preprocedural planning and intraprocedural guidance for transcatheter intervention relies on a comprehensive understanding of tricuspid anatomy and the use of 3-dimensional transesophageal echocardiography. The incorporation of computed tomography and cardiac magnetic resonance imaging likely will provide increasing accuracy and optimization of procedural success.

Multimodality imaging for the quantitative assessment of mitral regurgitation

The natural history of mitral regurgitation (MR) results in significant morbidity and mortality. Innovations in non-invasive imaging have provided new insights into the pathophysiology and quantification of MR, in addition to early detection of left ventricular (LV) dysfunction and prognostic assessment in asymptomatic patients. Transthoracic (TTE) and transesophageal (TOE) echocardiography are the mainstay for diagnosis, assessment and serial surveillance. However, the advance from 2D to 3D imaging leads to improved assessment and characterization of mitral valve (MV) disease. Cardiovascular magnetic resonance (CMR) is increasingly used for MR quantitation and can provide an alternative imaging method if echocardiography is suboptimal or inconclusive. Other techniques such as exercise echocardiography, tissue Doppler imaging and speckle-tracking echocardiography can further offer complementary information on prognosis. This review summarises the current evidence for state-of-the-art cardiovascular imaging for the investigation of MR. Whilst advanced echocardiographic techniques are superior in the evaluation of complex MV anatomy, CMR appears the most accurate technique for the quantification of MR severity. Integration of multimodality imaging for the assessment of MR utilises the advantages of each imaging technique and offers the most comprehensive assessment of MR.

Secondary mitral regurgitation (part 2): deliberations on mitral surgery and transcatheter repair

Secondary mitral regurgitation (MR) develops as a consequence of postinfarction remodelling of the ventricle or other causes of left ventricular (LV) dilatation and dysfunction. The presence of MR amplifies the poor prognosis of the failing ventricle, but it has not been established whether the adverse outcomes stem from the MR or whether the MR is simply a marker of progressive LV dysfunction. In this article, an attempt will be made to clarify the clinical impact of mitral surgery and transcatheter repair in patients with secondary MR. Observational studies indicate symptomatic improvement, but the results of randomised trials are mixed. Furthermore, neither mitral surgery nor transcatheter repair consistently leads to reversal of the adverse LV remodelling. There is, however, general agreement that these procedures do not have a salutary effect on survival. Certainly mitral surgery and transcatheter repair can substantially reduce the mitral regurgitant flow, but inconsistencies and uncertainties regarding clinical outcomes persist in the published literature. Some such problems could be resolved by utilisation of more accurate and reproducible imaging modalities in randomised studies of patients who are most likely to benefit from a reduction in the regurgitant volume—namely those with the most severe MR.

Quantification of mitral regurgitation in patients with hypertrophic cardiomyopathy using aortic and pulmonary flow data: impacts of left ventricular outflow tract obstruction and different left ventricular segmentation methods

BACKGROUND

Cardiovascular magnetic resonance (CMR) imaging in patients with hypertrophic cardiomyopathy (HCM) enables the assessment of not only left ventricular (LV) hypertrophy and scarring but also the severity of mitral regurgitation. CMR assessment of mitral regurgitation is primarily based on the difference between LV stroke volume (LVSV) and aortic forward flow (Ao) measured using the phase-contrast (PC) technique. However, LV outflow tract (LVOT) obstruction causing turbulent, non-laminar flow in the ascending aorta may impact the accuracy of aortic flow quantification, leading to false conclusions regarding mitral regurgitation severity. Thus, we decided to quantify mitral regurgitation in patients with HCM using Ao or, alternatively, main pulmonary artery forward flow (MPA) for mitral regurgitation volume (MRvol) calculations.

METHODS

The analysis included 143 prospectively recruited subjects with HCM and 15 controls. MRvol was calculated as the difference between LVSV computed with either the inclusion (LVSVincl) or exclusion (LVSVexcl) of papillary muscles and trabeculations from the blood pool and either Ao (MRvolAoi or MRvolAoe) or MPA (MRvolMPAi or MRvolMPAe). The presence or absence of LVOT obstruction was determined based on Doppler echocardiography findings.

RESULTS

MRvolAoi was higher than MRvolMPAi in HCM patients with LVOT obstruction [47.0 ml, interquartile range (IQR) = 31.5-60.0 vs. 35.5 ml, IQR = 26.0-51.0; p < 0.0001] but not in non-obstructive HCM patients (23.0 ml, IQR = 16.0-32.0 vs. 24.0 ml, IQR = 15.3-32.0; p = 0.26) or controls (18.0 ml, IQR = 14.3-21.8 vs. 20.0 ml, IQR = 14.3-22.0; p = 0.89). In contrast to controls and HCM patients without LVOT obstruction, in HCM patients with LVOT obstruction, aortic flow-based MRvol (MRvolAoi) was higher than pulmonary-based findings (MRvolMPAi) (bias = 9.5 ml; limits of agreement: -11.7-30.7 with a difference of 47 ml in the extreme case). The differences between aortic-based and pulmonary-based MRvol values calculated using LVSVexcl mirrored those derived using LVSVincl. However, MRvol values calculated using LVSVexcl were lower in all the groups analyzed (HCM with LVOT obstruction, HCM without LVOT obstruction, and controls) and with all methods of MRvol quantification used (p ≤ 0.0001 for all comparisons).

CONCLUSIONS

In HCM patients, LVOT obstruction significantly affects the estimation of aortic flow, leading to its underestimation and, consequently, to higher MRvol values than those obtained with MPA-based MRvol calculations.

Assessment of mitral regurgitation by 3-dimensional proximal flow convergence using magnetic resonance imaging: comparison with echo-Doppler

To test the feasibility of assessing mitral regurgitation (MR) severity using cardiac magnetic resonance (CMR) 4D velocity vectors to quantify regurgitant volume (RVol) by analysis of the proximal flow convergence, compared to Doppler based proximal isovelocity surface area (PISA) and CMR volume-based methods. In a prospectively designed study, 27 patients with various grades of MR underwent CMR and echo-Doppler on the same day. By CMR, multiple slices were obtained parallel to the mitral valve by phase-contrast imaging, using 3D velocity vectors, as well as short-axis cine images for left and right ventricular volume measurements. Using dedicated software developed in our laboratory, the perimeter of the proximal flow convergence region was semi-automatically measured for each temporal phase, and for each short-axis slice. The CMR-PISA RVol was calculated as the sum of PISA perimeters throughout systole, multiplied by slice width. For comparison, CMR-volumetric RVol was calculated by 2 methods: Volumetric (difference between left and right ventricular stroke volumes) and Flow-based (stroke volume -aortic flow). Echo-PISA RVol was calculated by echo-Doppler based PISA method. RVol by CMR-PISA correlated highly with echo-PISA (r = 0.87) and with CMR-volumetric (r = 0.86) and CMR-flow (r = 0.72). For comparison Doppler-RVol and CMR-volume-based RVol had r = 0.83. On average CMR-PISA was 16 ± 25 ml less than echo-PISA, but 12 ± 22 ml larger than CMR-volumetric RVol. The observed 3D shape of the PISA envelope by 4D-CMR resembled a hemiellipsoid rather than a hemisphere. This feasibility study suggests that CMR-based 4D-PISA may be able to assess MR severity quantitatively without any geometric assumptions.

Imaging of Cardiovascular Disease in Pregnancy and the Peripartum Period

OPINION STATEMENT

Cardiovascular disease is an important cause of morbidity and mortality during pregnancy and the postpartum period. During pregnancy, the cardiovascular system undergoes extensive hemodynamic, hormonal, and microstructural changes which may exacerbate a preexisting underlying cardiovascular condition or predispose to cardiovascular complications not typically seen in young healthy women. Such conditions include spontaneous coronary artery dissection, atherosclerotic coronary artery disease, and peripartum cardiomyopathy. When evaluating this patient population, the diagnostic strategy should be tailored to specifically assess this distinct disease spectrum. The choice of imaging techniques must also consider potential risks to both the mother and child; a unique challenge of diagnostic imaging during pregnancy. The risk of radiation from radiography, computed tomography, and nuclear medicine imaging; iodinated and gadolinium-based contrast media for computed tomography and magnetic resonance imaging respectively; and heat deposition from sonography are of special importance during pregnancy. A thorough understanding of pregnancy-specific cardiovascular complications and the capabilities and risks of available diagnostic imaging modalities is crucial to appropriately manage the pregnant patient.

Multi-Modality Imaging in the Evaluation and Treatment of Mitral Regurgitation

OPINION STATEMENT

Mitral regurgitation (MR) is frequent and associated with increased mortality and morbidity when severe. It may be caused by intrinsic valvular disease (primary MR) or ventricular deformation (secondary MR). Imaging has a critical role to document the severity, mechanism, and impact of MR on heart function as selected patients with MR may benefit from surgery whereas other will not. In patients planned for a surgical intervention, imaging is also important to select candidates for mitral valve (MV) repair over replacement and to predict surgical success. Although standard transthoracic echocardiography is the first-line modality to evaluate MR, newer imaging modalities like three-dimensional (3D) transesophageal echocardiography, stress echocardiography, cardiac magnetic resonance (CMR), and computed tomography (CT) are emerging and complementary tools for MR assessment. While some of these modalities can provide insight into MR severity, others will help to determine its mechanism. Understanding the advantages and limitations of each imaging modality is important to appreciate their respective role for MR assessment and help to resolve eventual discrepancies between different diagnostic methods. With the increasing use of transcatheter mitral procedures (repair or replacement) for high-surgical-risk patients, multimodality imaging has now become even more important to determine eligibility, preinterventional planning, and periprocedural guidance.

Secondary mitral regurgitation (part 1): volumetric quantification and analysis

Secondary mitral regurgitation (MR) develops as a consequence of left ventricular (LV) dilatation and dysfunction, which complicates its evaluation and management. The goal of this article is to review the assessment of secondary MR with special emphasis on quantification and analysis of LV volume data. At the present time, the optimal method for making these measurements appears to be cardiac MRI. In severe MR (both primary and secondary), the regurgitant fraction (RF) exceeds 50%, and as a result, the LV end diastolic volume (EDV) is increased. In secondary MR, the ejection fraction is depressed (generally <40%) and despite an RF >50%, the regurgitant volume (RegV) rarely meets the current published criteria for severe MR (>60 mL). The ratio of the RegV to EDV, which is very low in secondary MR, reflects the effect of the RegV on the ventricle and it may be predictive of the fractional change in LV size that can be expected after correction of MR. Accurate measurement of the volumetric parameters is essential to proper management of patients with secondary MR.

An easy-to-use scoring index to determine severity of mitral regurgitation by 2D echocardiography in clinical practice

PURPOSE

Mitral regurgitation (MR) grading by two-dimensional transthoracic echocardiography is challenging, but important to determine the best treatment strategy in patients with MR. Current guidelines advocate an integrative approach, although no recommendation is provided on how to do so. An easy-to-use index will be helpful for standardized and reproducible MR grading.

METHODS

Eleven echocardiographic parameters were retrospectively evaluated in 145 patients with moderate or severe MR. Parameters were scored positive or negative for severe MR, where expert panel consensus reading was considered as the reference standard. Logistic regression was performed, and adjusted coefficients were used to create a risk score for severe MR per patient (ROSE-index). The best cutoff with corresponding predictive values was determined.

RESULTS

Eighty-two percent of all parameters could be determined. Multivariable analysis revealed five parameters that remained significant predictors for severe MR: morphology, jet characteristics, vena contracta, systolic reversal, and left ventricular dimensions. With different weighing, a total score of 8 could be obtained. Median total ROSE-index score for moderate (2.0) and severe MR (5.0) did significantly differ. The cutoff score (≥4) revealed sensitivity 0.84 and specificity 0.83 to diagnose severe MR. Negative predictive value was 100% for score 0 and 1; score 6-8 showed a 100% positive predictive value. Inter- and intra-observer agreements were excellent (K-values >0.80).

CONCLUSION

Here, we propose an easy-to-use tool for integrated analysis of guideline parameters to assess MR severity. Using this so-called ROSE-index revealed reliable and reproducible assessment of severe MR (cutoff≥4) that may be helpful for clinical decision making.

Utility of cardiac magnetic resonance for evaluation of mitral regurgitation prior to mitral valve surgery

Mitral regurgitation (MR) is a common cause of morbidity worldwide and an accepted indication for interventional therapies which aim to reduce or resolve adverse clinical outcomes associated with MR. Cardiac magnetic resonance (CMR) provides highly accurate means of assessing MR, including a variety of approaches that can measure MR based on quantitative flow. Additionally, CMR is widely accepted as a reference standard for cardiac chamber quantification, enabling reliable detection of subtle changes in cardiac chamber size and function so as to guide decision-making regarding timing of mitral valve directed therapies. Beyond geometric imaging, CMR enables tissue characterization of ischemia and infarction in the left ventricular (LV) myocardium as well as within the mitral valve apparatus, thus enabling identification of structural substrates for MR. This review provides an overview of established and emerging CMR approaches to measure valvular regurgitation, including relative utility of different approaches for patients with primary or secondary MR. Clinical outcomes studies are discussed with focus on data demonstrating advantages of CMR for guiding diagnosis, risk stratification, and management of patients with known or suspected MR. Comparative data is reviewed with focus on diagnostic performance of CMR in comparison to conventional assessment via echocardiography (echo). Emerging literature is reviewed concerning potential new approaches that utilize CMR tissue characterization to guide clinical decision-making in order to improve therapeutic outcomes and clinical prognosis for patients with MR.