Myocardial extracellular volume by T1 mapping: a new marker of arrhythmia in mitral valve prolapse

Prevalence of Mitral Annular Disjunction at Cardiac MRI: Results from a Multicenter Registry

Purpose To determine the prevalence of mitral annular disjunction (MAD) in patients undergoing cardiac MRI for various clinical indications and to assess the association of MAD with arrhythmia, mitral valve prolapse (MVP), and myocardial alteration. Materials and Methods This study analyzed data from a retrospective observational registry of consecutive patients undergoing cardiac MRI for different clinical indications. Cardiac MRI examinations were performed from January 2019 to June 2019 at 13 Italian hospitals. Images underwent double reading by expert cardiac radiologists from the enrolling center and the core laboratory to assess the presence of MAD. Presence and maximum length of MAD and its association to MVP pattern, functional and structural myocardial alteration, and arrhythmia were evaluated using nonparametric and parametric tests. Logistic regression models were used to identify predictors of arrhythmia. Results Cardiac MRI studies from 2611 consecutive patients (1730, 66% male; median age, 53 years; IQR, 39-65 years) were evaluated. Prevalence of MAD was 5.44% (142 of 2611). MAD was an incidental finding in 74.6% (106 of 142) of patients. Patients with MAD had a higher prevalence of arrhythmias compared with patients without MAD (40% [57 of 142] vs 18% [444 of 2469]; P < .001). Patients with MAD and bileaflet MVP showed a longer MAD compared with patients with single-leaflet or absent MVP (median, 7 mm [IQR, 3-9.5 mm] vs 4 mm [IQR, 3-5 mm]; P < .001), a higher prevalence of systolic curling (75% [21 of 28] vs 30.7% [35 of 114]; P < .001), higher extracellular volume values (30% [IQR, 28%-32%] vs 27% [IQR, 25%-30%]; P = .04), and a higher prevalence of arrhythmia (64.2% [18 of 28] vs 34.2% [39 of 114]; P = .006). MAD length of at least 5 mm was an independent predictor of arrhythmia (odds ratio 3.96; 95% CI: 1.93, 8.15; P < .001). Conclusion MAD was a frequent incidental finding on cardiac MRI scans from a multicenter registry. MAD length of at least 5 mm and coexisting bileaflet MVP showed a higher risk of arrhythmia. Keywords: MR Imaging, Cardiac, Mitral Annular Disjunction Supplemental material is available for this article. ©RSNA, 2024.

Cardiovascular magnetic resonance imaging in mitral valve disease

This paper describes the role of cardiovascular magnetic resonance (CMR) imaging in assessing patients with mitral valve disease. Mitral regurgitation (MR) is one of the most prevalent valvular heart diseases. It often progresses without significant symptoms, leading to left ventricular overload, dysfunction, frequent decompensated heart failure episodes, and excess mortality. Cardiovascular magnetic resonance assessment is recommended for MR when routine ultrasound imaging information is insufficient or discordant. A well-planned CMR can provide an in-depth assessment of the mitral valve apparatus, leaflet morphology, and papillary muscles. In addition, it can precisely inform the impact of MR on left atrial and ventricular remodelling. The review aims to highlight established and emerging techniques for morphological assessment, flow assessment (including regurgitation and stenosis), myocardial assessment, and haemodynamic assessment of mitral valve disease by CMR. It also proposes a simplified clinical flow chart for CMR assessment of the mitral valve.

Assessment of Myocardial Fibrosis in Marfan Syndrome Using Cardiac Magnetic Resonance Imaging

BACKGROUND

Impaired myocardial function and arrhythmia are important manifestations of Marfan syndrome (MFS). Studies assessing myocardial fibrosis in relation to these manifestations are scarce.

METHODS

This cross-sectional, single-center study assessed ventricular volumes, ventricular function, and myocardial fibrosis by cardiac magnetic resonance imaging (CMR) in patients with MFS harboring a (likely) pathogenic FBN1 variant. The presence and extent of fibrosis were assessed by late gadolinium enhancement (LGE) and extracellular volume measurement (ECV). Data on 24-h Holter monitoring and clinical data were extracted from electronic patient records.

RESULTS

The study included 32 unselected patients with MFS (median age 38 years [range 10-69], 41% women). No focal myocardial fibrosis was detected. Six patients (21%) had diffuse fibrosis (ECV > 29%). No association was found between the presence of diffuse fibrosis and clinically relevant myocardial dysfunction. Five patients (16%) had reduced left ventricular ejection fraction (LVEF < 55%). While all of these exhibited mitral annular disjunction (MAD), only two had ECV > 29%. Patients with MAD had increased indexed LV volumes (median end-diastolic volume, 92 mL/m2 [IQR, 78-100] vs. 78 mL/m2 [IQR, 71-87]; median end-systolic volume, 31 mL/m2 [IQR, 23-46] vs. 22 mL/m2 [IQR, 21-28]), also after adjusting for the presence of mitral and aortic valve regurgitation. No differences in ECV were seen between patients with and without MAD.

CONCLUSIONS

In this cohort of patients with MFS, focal myocardial fibrosis was not detected using CMR. Although diffuse fibrosis was observed in 21% of patients, no evident connection to clinically relevant myocardial dysfunction was found. Further studies should evaluate the impact of diffuse fibrosis on clinical outcome prediction.

Role of cardiac magnetic resonance in stratifying arrhythmogenic risk in mitral valve prolapse patients: a systematic review and meta-analysis

OBJECTIVES

To perform a systematic review and meta-analysis of studies investigating the diagnostic value of cardiac magnetic resonance (CMR) features for arrhythmic risk stratification in mitral valve prolapse (MVP) patients.

MATERIALS AND METHODS

EMBASE, PubMed/MEDLINE, and CENTRAL were searched for studies reporting MVP patients who underwent CMR with assessment of: left ventricular (LV) size and function, mitral regurgitation (MR), prolapse distance, mitral annular disjunction (MAD), curling, late gadolinium enhancement (LGE), and T1 mapping, and reported the association with arrhythmia. The primary endpoint was complex ventricular arrhythmias (co-VAs) as defined by any non-sustained ventricular tachycardia, sustained ventricular tachycardia, ventricular fibrillation, or aborted sudden cardiac death. Meta-analysis was performed when at least three studies investigated a CMR feature. PROSPERO registration number: CRD42023374185.

RESULTS

The meta-analysis included 11 studies with 1278 patients. MR severity, leaflet length/thickness, curling, MAD distance, and mapping techniques were not meta-analyzed as reported in < 3 studies. LV end-diastolic volume index, LV ejection fraction, and prolapse distance showed small non-significant effect sizes. LGE showed a strong and significant association with co-VA with a LogORs of 2.12 (95% confidence interval (CI): [1.00, 3.23]), for MAD the log odds-ratio was 0.95 (95% CI: [0.30, 1.60]). The predictive accuracy of LGE was substantial, with a hierarchical summary ROC AUC of 0.83 (95% CI: [0.69, 0.91]) and sensitivity and specificity rates of 0.70 (95% CI: [0.41, 0.89]) and 0.80 (95% CI: [0.67, 0.89]), respectively.

CONCLUSIONS

Our study highlights the role of LGE as the key CMR feature for arrhythmia risk stratification in MVP patients. MAD might complement arrhythmic risk stratification.

CLINICAL RELEVANCE STATEMENT

LGE is a key factor for arrhythmogenic risk in MVP patients, with additional contribution from MAD. Combining MRI findings with clinical characteristics is critical for evaluating and accurately stratifying arrhythmogenic risk in MVP patients.

KEY POINTS

MVP affects 2-3% of the population, with some facing increased risk for arrhythmia. LGE can assess arrhythmia risk, and MAD may further stratify patients. CMR is critical for MVP arrhythmia risk stratification, making it essential in a comprehensive evaluation.

Interstitial fibrosis and arrhythmic mitral valve prolapse: Unraveling sex-based differences

BACKGROUND

Interstitial fibrosis as quantified by cardiovascular magnetic resonance (CMR) has been demonstrated in arrhythmic mitral valve prolapse (AMVP), a condition with known female predominance. Prior studies of interstitial fibrosis in AMVP have only included cases with significant mitral regurgitation (MR) or mitral annular disjunction (MAD), limiting our understanding of alternative arrhythmic mechanisms in mitral valve prolapse (MVP). We sought to evaluate the association between interstitial fibrosis and AMVP, regardless of MAD and without severe MR, while also investigating the contribution of sex to this association.

METHODS

We performed research-based contrast CMR in consecutive individuals with MVP between 2019 and 2022. Extracellular volume fraction (ECV%), a surrogate marker for interstitial fibrosis, was quantified using T1 mapping in the basal and mid-left ventricular slices. Replacement fibrosis was assessed using late gadolinium enhancement (LGE). AMVP was defined as MVP with frequent premature ventricular contractions and/or non-sustained/sustained ventricular tachycardia (VT) or fibrillation (VF).

RESULTS

We identified 65 MVP cases without severe MR (30 [46%] women, 22 [34%] no/trace, 30 [44%] mild, and 13 [21%] moderate MR) and with adequate ECV% measurement. Among these, 38% were classified as AMVP, including two cases of aborted VF arrest, both in premenopausal females. Global ECV% was significantly higher in AMVP vs non-AMVP (31% [27-33] vs 27% [23-30], p = 0.002). In the AMVP group, higher segmental ECV% was not limited to the inferolateral/inferior walls, typically subject to myocardial traction by the prolapsing leaflets/MAD but was more diffuse and involved atypical segments such as the anterior/anterolateral walls (p < 0.05). The association between AMVP and global ECV% was driven by female sex (32% [30-34] vs 27% [25-30], p = 0.002 in females; 28% [23-32] vs 26% [23-30], p = 0.41 in males). ECV% remained independently associated with an increased risk of arrhythmic events, including VT/VF (p < 0.01), even after adjustment for cardiovascular risk factors, MAD, and LGE (p < 0.01).

CONCLUSION

In MVP without significant MR, interstitial fibrosis by CMR is associated with an increased risk of arrhythmic events, suggesting a primary myopathic process. The selective association between interstitial fibrosis and AMVP in females may explain why severe arrhythmic complications are more prevalent among women.

Mitral Annular Disjunction in the Context of Mitral Valve Prolapse: Identifying the At-Risk Patient

Mitral annular disjunction (MAD), a separation between the left atrium/mitral valve annulus and the left ventricular myocardium, is frequently seen in patients with arrhythmic mitral valve prolapse. Although an association exists between MAD and ventricular arrhythmias, little is known regarding the identification of individuals at high risk. Multimodality imaging including echocardiography, computed tomography, cardiac magnetic resonance, and positron emission tomography can play an important role in both the diagnosis and risk stratification of MAD. Due to a paucity of data, clinical decision making in a patient with MAD is challenging and remains largely empirical. Although MAD itself can be corrected surgically, the prevention and treatment of associated arrhythmias may require medical therapy, catheter ablation, and an implantable cardioverter-defibrillator. Prospective data are required to define the role of implantable cardioverter-defibrillators, targeted catheter ablation, and surgical correction in selected, at-risk patients.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Imaging for the assessment of the arrhythmogenic potential of mitral valve prolapse

Mitral valve prolapse (MVP) is the most common valve disease in the western world and recently emerged as a possible substrate for sudden cardiac death (SCD). It is estimated an annual risk of sudden cardiac death of 0.2 to 1.9% mostly caused by complex ventricular arrhythmias (VA). Several mechanisms have been recognized as potentially responsible for arrhythmia onset in MVP, resulting from the combination of morpho-functional abnormality of the mitral valve, structural substrates (regional myocardial hypertrophy, fibrosis, Purkinje fibers activity, inflammation), and mechanical stretch. Echocardiography plays a central role in MVP diagnosis and assessment of severity of regurgitation. Several abnormalities detectable by echocardiography can be prognostic for the occurrence of VA, from morphological alteration including leaflet redundancy and thickness, mitral annular dilatation, and mitral annulus disjunction (MAD), to motion abnormalities detectable with "Pickelhaube" sign. Additionally, speckle-tracking echocardiography may identify MVP patients at higher risk for VA by detection of increased mechanical dispersion. On the other hand, cardiac magnetic resonance (CMR) has the capability to provide a comprehensive risk stratification combining the identification of morphological and motion alteration with the detection of myocardial replacement and interstitial fibrosis, making CMR an ideal method for arrhythmia risk stratification in patients with MVP. Finally, recent studies have suggested a potential role in risk stratification of new techniques such as hybrid PET-MR and late contrast enhancement CT. The purpose of this review is to provide an overview of the mitral valve prolapse syndrome with a focus on the role of imaging in arrhythmic risk stratification. CLINICAL RELEVANCE STATEMENT: Mitral valve prolapse is the most frequent valve condition potentially associated with arrhythmias. Imaging has a central role in the identification of anatomical, functional, mechanical, and structural alterations potentially associated with a higher risk of developing complex ventricular arrhythmia and sudden cardiac death. KEY POINTS: • Mitral valve prolapse is a common valve disease potentially associated with complex ventricular arrhythmia and sudden cardiac death. • The mechanism of arrhythmogenesis in mitral valve prolapse is complex and multifactorial, due to the interplay among multiple conditions including valve morphological alteration, mechanical stretch, myocardial structure remodeling with fibrosis, and inflammation. • Cardiac imaging, especially echocardiography and cardiac magnetic resonance, is crucial in the identification of several features associated with the potential risk of serious cardiac events. In particular, cardiac magnetic resonance has the advantage of being able to detect myocardial fibrosis which is currently the strongest prognosticator.

The Association Between Late Gadolinium Enhancement by Cardiac Magnetic Resonance and Ventricular Arrhythmia in Patients With Mitral Valve Prolapse: A Systematic Review and Meta-Analysis

INTRODUCTION

Malignant ventricular arrhythmia (VA) and sudden cardiac death (SCD) have been reported in patients with mitral valve prolapse (MVP); however, effective risk stratification methods are still lacking. Myocardial fibrosis is thought to play an important role in the development of VA; however, observational studies have produced contradictory findings regarding the relationship between VA and late gadolinium enhancement (LGE) in MVP patients. The aim of this meta-analysis and systematic review of observational studies was to investigate the association between left ventricular LGE and VA in patients with MVP.

METHODS

We searched the PubMed, Embase, and Web of Science databases from 1993 to 2023 to identify case-control, cross-sectional, and cohort studies that compared the incidence of VA in patients with MVP who had left ventricular LGE and those without left ventricular LGE.

RESULTS

A total of 1464 subjects with MVP from 12 observational studies met the eligibility criteria. Among them, VA episodes were reported in 221 individuals (15.1%). Meta-analysis demonstrated that the presence of left ventricular LGE was significantly associated with an increased risk of VA (pooled risk ratio 2.96, 95% CI: 2.26-3.88, p for heterogeneity = 0.07, I2 = 40%). However, a meta-regression analysis of the prevalence of mitral regurgitation (MR) showed that the severity of MR did not significantly affect the association between the occurrence of LGE and VA (p = 0.079).

CONCLUSION

The detection of LGE could be helpful for stratifying the risk of VA in patients with MVP.

Left Ventricular Fibrosis by Cardiac Magnetic Resonance Tissue Characterization in Chronic Mitral Regurgitation Patients

Background: Left ventricular remodeling in chronic mitral regurgitation (MR) encompasses two types of myocardial fibrosis: replacement fibrosis, identified by late gadolinium enhancement (LGE), and diffuse interstitial fibrosis, assessed by pre- and postcontrast T1 mapping techniques. These may explain irreversible LV dysfunction after MR correction. We aimed to assess the presence of myocardial fibrosis in patients with moderate and severe MR with no criteria for surgery versus mild MR controls. Methods: We enrolled 137 patients with chronic primary MR and 130 controls; all underwent cardiac magnetic resonance, and were followed up in a median of 2.9 years to assess mortality and the need for mitral valve replacement. Results: Patients in the study group displayed significantly higher degrees of LGE (28.4% vs 7.69%, p < 0.05), higher native T1 values (1167 ± 58.5 versus 971 ± 51.4 (p < 0.05)), and higher extracellular volumes compared to controls (32.3% ± 3.5 versus 23.9 ± 2.2, (p < 0.05)). The composite outcome occurred in 28 patients in the study group (20.4%), and significantly higher with LGE+ (78.5%). Replacement fibrosis (HR = 1.83, 95% CI, p < 0.01) and interstitial fibrosis (HR = 1.61, 95% CI, p < 0.01) were independent predictors for the composite outcome. Conclusions: Patients with moderate and severe MR with no criteria for surgery still exhibit a significant degree of both replacement and interstitial fibrosis, with prognostic implications.

Arrhythmic Mitral Valve Prolapse Phenotype: An Unsupervised Machine Learning Analysis Using a Multicenter Cardiac MRI Registry

Purpose To use unsupervised machine learning to identify phenotypic clusters with increased risk of arrhythmic mitral valve prolapse (MVP). Materials and Methods This retrospective study included patients with MVP without hemodynamically significant mitral regurgitation or left ventricular (LV) dysfunction undergoing late gadolinium enhancement (LGE) cardiac MRI between October 2007 and June 2020 in 15 European tertiary centers. The study end point was a composite of sustained ventricular tachycardia, (aborted) sudden cardiac death, or unexplained syncope. Unsupervised data-driven hierarchical k-mean algorithm was utilized to identify phenotypic clusters. The association between clusters and the study end point was assessed by Cox proportional hazards model. Results A total of 474 patients (mean age, 47 years ± 16 [SD]; 244 female, 230 male) with two phenotypic clusters were identified. Patients in cluster 2 (199 of 474, 42%) had more severe mitral valve degeneration (ie, bileaflet MVP and leaflet displacement), left and right heart chamber remodeling, and myocardial fibrosis as assessed with LGE cardiac MRI than those in cluster 1. Demographic and clinical features (ie, symptoms, arrhythmias at Holter monitoring) had negligible contribution in differentiating the two clusters. Compared with cluster 1, the risk of developing the study end point over a median follow-up of 39 months was significantly higher in cluster 2 patients (hazard ratio: 3.79 [95% CI: 1.19, 12.12], P = .02) after adjustment for LGE extent. Conclusion Among patients with MVP without significant mitral regurgitation or LV dysfunction, unsupervised machine learning enabled the identification of two phenotypic clusters with distinct arrhythmic outcomes based primarily on cardiac MRI features. These results encourage the use of in-depth imaging-based phenotyping for implementing arrhythmic risk prediction in MVP. Keywords: MR Imaging, Cardiac, Cardiac MRI, Mitral Valve Prolapse, Cluster Analysis, Ventricular Arrhythmia, Sudden Cardiac Death, Unsupervised Machine Learning Supplemental material is available for this article. © RSNA, 2024.

Mitral annular disjunction in idiopathic ventricular fibrillation patients: just a bystander or a potential cause?

AIMS

Previously, we demonstrated that inferolateral mitral annular disjunction (MAD) is more prevalent in patients with idiopathic ventricular fibrillation (IVF) than in healthy controls. In the present study, we advanced the insights into the prevalence and ventricular arrhythmogenicity by inferolateral MAD in an even larger IVF cohort.

METHODS AND RESULTS

This retrospective multi-centre study included 185 IVF patients [median age 39 (27, 52) years, 40% female]. Cardiac magnetic resonance images were analyzed for mitral valve and annular abnormalities and late gadolinium enhancement. Clinical characteristics were compared between patients with and without MAD. MAD in any of the 4 locations was present in 112 (61%) IVF patients and inferolateral MAD was identified in 24 (13%) IVF patients. Mitral valve prolapse (MVP) was found in 13 (7%) IVF patients. MVP was more prevalent in patients with inferolateral MAD compared with patients without inferolateral MAD (42 vs. 2%, P < 0.001). Pro-arrhythmic characteristics in terms of a high burden of premature ventricular complexes (PVCs) and non-sustained ventricular tachycardia (VT) were more prevalent in patients with inferolateral MAD compared to patients without inferolateral MAD (67 vs. 23%, P < 0.001 and 63 vs. 41%, P = 0.046, respectively). Appropriate implantable cardioverter defibrillator therapy during follow-up was comparable for IVF patients with or without inferolateral MAD (13 vs. 18%, P = 0.579).

CONCLUSION

A high prevalence of inferolateral MAD and MVP is a consistent finding in this large IVF cohort. The presence of inferolateral MAD is associated with a higher PVC burden and non-sustained VTs. Further research is needed to explain this potential interplay.

Multiparametric Mapping via Cardiovascular Magnetic Resonance in the Risk Stratification of Ventricular Arrhythmias and Sudden Cardiac Death

Risk stratification for malignant ventricular arrhythmias and sudden cardiac death is a daunting task for physicians in daily practice. Multiparametric mapping sequences obtained via cardiovascular magnetic resonance imaging can improve the risk stratification for malignant ventricular arrhythmias by unveiling the presence of pathophysiological pro-arrhythmogenic processes. However, their employment in clinical practice is still restricted. The present review explores the current evidence supporting the association between mapping abnormalities and the risk of ventricular arrhythmias in several cardiovascular diseases. The key message is that further clinical studies are needed to test the additional value of mapping techniques beyond conventional cardiovascular magnetic resonance imaging for selecting patients eligible for an implantable cardioverter defibrillator.

Interstitial Fibrosis and Arrhythmic Mitral Valve Prolapse: Unravelling Sex-Based Differences

Background

Interstitial fibrosis as quantified by cardiac magnetic resonance (CMR) has been demonstrated in arrhythmic mitral valve prolapse (MVP), a condition with known female predominance. However, prior studies included only MVP cases with significant mitral regurgitation (MR) or mitral annular disjunction (MAD). We sought to evaluate the association between interstitial fibrosis and complex ventricular ectopy (ComVE) in MVPs unselected for MAD or severe MR, and to investigate the contribution of sex to this association.

Methods

We performed contrast CMR in consecutive individuals with MVP between 2020 and 2022. Extracellular volume fraction (ECV%), a surrogate marker for interstitial fibrosis, was quantified using T 1 mapping. Replacement fibrosis was assessed using late gadolinium enhancement (LGE). ComVE, defined as frequent premature ventricular contractions and/or non-sustained/sustained ventricular tachycardia (VT), was detected using ambulatory ECG monitoring.

Results

We identified 59 MVP cases without severe MR (49% women, 80% with mild or less MR) and available ECV% measurement. Among these, 23 (39%) had ComVE, including a case of aborted ventricular fibrillation (VF) and one with sudden arrhythmic death, both females. Global ECV% was significantly greater in ComVE versus non-ComVE (31%[27-33] vs 27%[23-30], p=0.002). In MVP-ComVE, higher segmental ECV% was not limited to the inferolateral/inferior LV wall, but was also demonstrated in atypical segments including the anterior/anterolateral wall (p<0.05). The association between ComVE and ECV% was driven by female sex (32%[30-33] vs 28%[26-30], p=0.003 in females; 31%[25-33] vs 26%[23-30], p=0.22 in males). ECV% remained independently associated with an increased risk of ComVE, including VT/VF, after adjustment for cardiovascular risk factors, MAD, and LGE (p<0.01).

Conclusion

In MVP without significant MR, interstitial fibrosis by CMR is associated with an increased risk of ComVE, suggesting a primary myopathic process. The stronger association between interstitial fibrosis and ComVE in females may explain why severe arrhythmic complications are more prevalent among women.

Abstract Figure

Mitral Annular Disjunction: Review of an Increasingly Recognized Mitral Valve Entity

Mitral annular disjunction (MAD) refers to atrial displacement of the hinge point of the mitral valve annulus from the ventricular myocardium. MAD leads to paradoxical expansion of the annulus in systole and may often be associated with mitral valve prolapse (MVP), leaflet degeneration, myocardial and papillary muscle fibrosis, and, potentially, malignant cardiac arrhythmias. Patients with MAD and MVP may present similarly, and MAD is potentially the missing link in explaining why some patients with MVP experience adverse outcomes. Patients with a 5 mm or longer MAD distance have an elevated risk of malignant cardiac arrhythmia compared with those with a shorter MAD distance. Evaluation for MAD is an important component of cardiac imaging, especially in patients with MVP and unexplained cardiac arrhythmias. Cardiac MRI is an important diagnostic tool that aids in recognizing and quantifying MAD, MVP, and fibrosis in the papillary muscle and myocardium, which may predict and help improve outcomes following electrophysiology procedures and mitral valve surgery. This article reviews the history, pathophysiology, controversy, prevalence, clinical implications, and imaging considerations of MAD, focusing on cardiac MRI. Keywords: MR-Dynamic Contrast Enhanced, Cardiac, Mitral Valve, Mitral Annular Disjunction, Mitral Valve Prolapse, Floppy Mitral Valve, Cardiac MRI, Arrhythmia, Sudden Cardiac Death, Barlow Valve © RSNA, 2023.

Arrhythmic mitral valve prolapse and mitral annular disjunction: pathophysiology, risk stratification, and management

Mitral valve prolapse (MVP) is the most frequent valve condition but remains a conundrum in many aspects, particularly in regard to the existence and frequency of an arrhythmic form (AMVP) and its link to sudden cardiac death. Furthermore, the presence, frequency, and significance of the anatomic functional feature called mitral annular disjunction (MAD) have remained widely disputed. Recent case series and cohorts have shattered the concept that MVP is most generally benign and have emphasized the various phenotypes associated with clinically significant ventricular arrhythmias, including AMVP. The definition, evaluation, follow-up, and management of AMVP represent the focus of the present review, strengthened by recent coherent studies defining an arrhythmic MVP phenotypic that would affect a small subset of patients with MVP at concentrated high risk. The role of MAD in this context is of particular importance, and this review highlights the characteristics of AMVP phenotypes and MAD, their clinical, multimodality imaging, and rhythmic evaluation. These seminal facts lead to proposing a risk stratification clinical pathway with consideration of medical, rhythmologic, and surgical management and have been objects of recent expert consensus statements and of proposals for new research directions.

The Role of Cardiovascular Magnetic Resonance Imaging in Patients with Cardiac Arrhythmias

Cardiac arrhythmias are associated with significant morbidity, mortality and poor quality of life. Cardiovascular magnetic resonance (CMR) imaging, with its unsurpassed capability of non-invasive tissue characterisation, high accuracy, and reproducibility of measurements, plays an integral role in determining the underlying aetiology of cardiac arrhytmias. CMR can reliably diagnose previous myocardial infarction, non-ischemic cardiomyopathy, characterise congenital heart disease and valvular pathologies, and also detect the underlying substrate concealed on conventional investigations in a significant proportion of patients with arrhythmias. Determining the underlying substrate of arrhythmia is of paramount importance for treatment planning and prognosis. However, CMR imaging in patients with irregular heart rates can be problematic. Understanding the different ways to overcome the limitations of CMR in arrhythmia is essential for providing high-quality imaging, comprehensive information, and definitive answers in this diverse group of patients.

Arrhythmic Mitral Valve Prolapse With Only Mild or Moderate Mitral Regurgitation: Characterization of Myocardial Substrate

BACKGROUND

Sustained ventricular tachycardia and sudden cardiac death due to degenerative mitral valve prolapse (MVP) can occur in the absence of severe mitral regurgitation (MR). A significant percentage of patients with MVP-related sudden death do not have any evidence of replacement fibrosis, suggesting other unrecognized proarrhythmic factors may place these patients at risk.

OBJECTIVES

This study aims to characterize myocardial fibrosis/inflammation and ventricular arrhythmia complexity in patients with MVP and only mild or moderate MR.

METHODS

Prospective observational study of patients with MVP and only mild or moderate MR underwent ventricular arrhythmia characterization and hybrid positron emission tomography (PET)/magnetic resonance imaging (MRI). Coregistered hybrid 18F-fluorodeoxyglucose (18F-FDG)-PET and MRI late gadolinium enhancement images were assessed and categorized. Recruitment occurred in the cardiac electrophysiology clinic.

RESULTS

In 12 patients with degenerative MVP with only mild or moderate MR, of which a majority had complex ventricular ectopy (n = 10, 83%), focal (or focal-on-diffuse) uptake of 18F-FDG (PET-positive) was detected in 83% (n = 10) of patients. Three-quarters of the patients (n = 9, 75%) had FDG uptake that coexisted with areas of late gadolinium enhancement (PET/MRI-positive). Abnormal T1, T2 and extracellular volume (ECV) values were observed in 58% (n = 7), 25% (n = 3), and 16% (n = 2), respectively.

CONCLUSIONS

Most patients with degenerative MVP, ventricular ectopy, and mild or moderate MR show myocardial inflammation that is concordant with myocardial scar. Further study is needed to determine whether these findings contribute to the observation that most MVP-related sudden deaths occur in patients with less than severe MR.

Predictors of Ventricular Arrhythmias in Patients With Mitral Valve Prolapse: A Meta-analysis

Mitral valve prolapse (MVP) has an estimated prevalence of 2-3% in the general population. Patients with MVP have an increased risk of ventricular arrhythmic events. The aim of this meta-analysis was to identify easily obtained markers that can be used for the arrhythmic risk stratification of MVP patients. This meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA Statement). The search strategy identified 23 studies that were finally included in the study. The quantitative synthesis showed that late gadolinium enhancement (LGE) [RR 6.40 (2.11-19.39), I2 77%, P = 0.001], longer QTc interval [mean difference: 14.2 (8.92-19.49) I2 0%, P < 0.001], T-wave inversion in inferior leads [RR 1.60 (1.39-1.86), I2 0%, P < 0.001], mitral annular disjunction (MAD) [RR 1.77 (1.29-2.44), I2 37%, P = 0.0005], lower left ventricular ejection fraction (LVEF) [mean difference: -0.77 (-1.48, -0.07) I2 0%, P = 0.03], bileaflet MVP [RR 1.32 (1.16-1.49), I2 0%, P < 0.001], increased anterior [mean difference: 0.45 (0.28, 0.61), I2 0%, P < 0.001] and posterior [mean difference: 0.39 (0.26, 0.52), I2 0%, P < 0.001] mitral leaflet thickness were significantly associated with ventricular arrhythmias in MVP patients. On the other hand, gender, QRS duration, anterior, and posterior mitral leaflet length were not associated with increased risk of arrhythmias. In conclusion, inferior T-wave inversions, QTc interval, LGE, LVEF, MAD, bileaflet MVP, anterior, and posterior mitral leaflet thickness are easily obtained markers that can be used for the risk stratification of patients with MVP. Prospective studies should be designed for the better stratification of this population.

Additional value of cardiac magnetic resonance feature tracking parameters for the evaluation of the arrhythmic risk in patients with mitral valve prolapse

OBJECTIVES

The identification of patients with mitral valve prolapse (MVP) presenting high arrhythmic risk remains challenging. Cardiovascular Magnetic Resonance (CMR) feature tracking (FT) may improve risk stratification. We analyzed the role of CMR-FT parameters in relation to the incidence of complex ventricular arrhythmias (cVA) in patients with MVP and mitral annular disjunction (MAD).

METHODS

42 patients with MVP and MAD who underwent 1.5 T CMR were classified as MAD-cVA (n = 23, 55%) in case of cVA diagnosed on a 24-h Holter monitoring and as MAD-noVA in the absence of cVA (n = 19, 45%). MAD length, late gadolinium enhancement (LGE), basal segments myocardial extracellular volume (ECV) and CMR-FT were assessed.

RESULTS

LGE was more frequent in the MAD-cVA group in comparison with the MAD-noVA group (78% vs 42%, p = 0.002) while no difference was observed in terms of basal ECV. Global longitudinal strain (GLS) was reduced in MAD-cVA compared to MAD-noVA (- 18.2% ± 4.6% vs - 25.1% ± 3.1%, p = 0.004) as well as global circumferential strain (GCS) at the mid-ventricular level (- 17.5% ± 4.7% vs - 21.6% ± 3.1%, p = 0.041). Univariate analysis identified as predictors of the incidence of cVA: GCS, circumferential strain (CS) in the basal and mid infero-lateral wall, GLS, regional longitudinal strain (LS) in the basal and mid-ventricular inferolateral wall. Reduced GLS [Odd ratio (OR):1.56 (confidence interval (CI) 95%: 1.45-2.47; p < 0.001)] and regional LS in the basal inferolateral wall [OR: 1.62 (CI 95%: 1.22-2.13; p < 0.001)] remained independent prognostic factors in multivariate analysis.

CONCLUSION

In patients with MVP and MAD, CMR-FT parameters are correlated with the incidence of cVA and may be of interest in arrhythmic risk stratification.

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.

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.

Mitral Valve Prolapse and Sudden Cardiac Death in Athletes at High Risk

Mitral valve prolapse (MVP) is the most frequent valvulopathy in the general population, with usually a favourable prognosis. Although it can be associated with some complications, ventricular arrhythmias (VA) and sudden cardiac death (SCD) are the most worrying. The estimated risk of SCD in MVP is between 0.2% to 1.9% per year, including MVP patients with and without severe mitral regurgitation (MR). The association between SCD and MVP is expressed by a phenotype called "malignant MVP" characterized by transthoracic echocardiography (TTE) findings such as bileaflet myxomatous prolapse and mitral annulus disjunction (MAD), ECG findings such as repolarization abnormalities, complex ventricular arrhythmias (c-VAs) and LV fibrosis of papillary muscles (PMs) and inferobasal wall visualized by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR). Therefore, attention is raised for patients with "arrhythmic MVP" characterized from an ECG point of view by frequent premature ventricular contractions (PVCs) arising from one or both PMs as well as by T-wave inversion in the inferolateral leads. In athletes, SCD is the most frequent medical cause of death and in young subjects (< 35 years) usually is due to electrical mechanism affecting who has a silent cardiovascular disease and are not considered per se a cause of increased mortality. In MVP, SCD was reported to happen during sports activity or immediately after and valve prolapse was the only pathological aspect detected. The aim of the present paper is to explore the association between SCD and MVP in athletes, focusing attention on ECG, TTE in particular, and CMR findings that could help to identify subjects at high risk for complex arrhythmias and eventually SCD. In addition, it is also examined if sports activity might predispose patients with MVP to develop major arrhythmias.

Imaging Considerations and Clinical Implications of Mitral Annular Disjunction

Mitral annular disjunction is increasingly recognized as an important anatomic feature of mitral valve disease. The presence of mitral annular disjunction, defined as separation between the left atrial wall at the point of mitral valve insertion and the left ventricular free wall, has been associated with increased degeneration of the mitral valve and increased incidence of sudden cardiac death. The clinical importance of this entity necessitates standard reporting on cardiovascular imaging reports if patients are to receive adequate risk stratification and management. We provide a narrative review of the literature pertaining to mitral annular disjunction, its clinical implications, and areas needing further research.

Mitral Valve Prolapse and Mitral Annular Disjunction Arrhythmic Syndromes: Diagnosis, Risk Stratification and Management

Although mitral valve prolapse (MVP) is usually considered a benign clinical condition, it has been linked with ventricular arrhythmias and sudden cardiac death in patients with a certain "arrhythmic" phenotype, raising awareness and mandating a specific risk stratification protocol. Mitral annular disjunction (MAD) is considered a "red flag" in malignant MVP syndrome along with bileaflet myxomatous prolapse, female gender, negative or biphasic T waves in the inferior leads, fibrosis in the papillary muscles or inferobasal wall detected by cardiac magnetic resonance imaging and complex arrhythmias of right bundle branch morphology. MAD seems to play a critical role in the chain of morphofunctional abnormalities which lead to increased mechanical stretch and subsequent fibrosis mainly in the papillary muscles, forming the vulnerable anatomic substrate prone to arrhythmogenesis, and associated with long-term severe ventricular arrhythmias. Arrhythmogenesis in MVP/MAD patients is not fully understood but a combination between a substrate and a trigger has been established with premature ventricular contraction triggered ventricular fibrillation being the main mechanism of sudden cardiac death (SCD). Certain characteristics mostly recognized by non-invasive imaging modalities serve as risk factors and can be used to diagnose and identify high risk patients with MAD, while treatment options include catheter ablation, device therapy and surgical intervention. This review focuses on the clinical presentation, the arrhythmogenic substrate, and the incidence of ventricular arrhythmias and SCD in MAD population. The current risk stratification tools in MAD arrhythmogenic entity are discussed.

State-of-the-Art Multimodality Imaging in Sudden Cardiac Arrest with Focus on Idiopathic Ventricular Fibrillation: A Review

Idiopathic ventricular fibrillation is a rare cause of sudden cardiac arrest and a diagnosis by exclusion. Unraveling the mechanism of ventricular fibrillation is important for targeted management, and potentially for initiating family screening. Sudden cardiac arrest survivors undergo extensive clinical testing, with a growing role for multimodality imaging, before diagnosing "idiopathic" ventricular fibrillation. Multimodality imaging, considered as using multiple imaging modalities as diagnostics, is important for revealing structural myocardial abnormalities in patients with cardiac arrest. This review focuses on combining imaging modalities (echocardiography, cardiac magnetic resonance and computed tomography) and the electrocardiographic characterization of sudden cardiac arrest survivors and discusses the surplus value of multimodality imaging in the diagnostic routing of these patients. We focus on novel insights obtained through electrostructural and/or electromechanical imaging in apparently idiopathic ventricular fibrillation patients, with special attention to non-invasive electrocardiographic imaging.

Arrhythmic Mitral Valve Prolapse and Mitral Annular Disjunction: Clinical Features, Pathophysiology, Risk Stratification, and Management

Mitral valve prolapse (MVP) is a common cause of valvular heart disease. Although many patients with MVP have a benign course, there is increasing recognition of an arrhythmic phenotype associated with ventricular arrhythmias and sudden cardiac death (SCD). Pathophysiologic mechanisms associated with arrhythmias include cardiac fibrosis, mechanical stress induced changes in ventricular refractory periods, as well as electrophysiologic changes in Purkinje fibers. Clinically, a variety of risk factors including demographic, electrocardiographic, and imaging characteristics help to identify patients with MVP at the highest at risk of SCD and arrhythmias. Once identified, recent advances in treatment including device therapy, catheter ablation, and surgical interventions show promising outcomes. In this review, we will summarize the incidence of ventricular arrhythmias and SCD in patients with MVP, the association with mitral annular disjunction, mechanisms of arrhythmogenesis, methods for arrhythmic and SCD risk stratification including findings with multimodality imaging, and treatments for the primary and secondary prevention of SCD.

Diagnosis of Mitral Valve Prolapse: Much More than Simple Prolapse. Multimodality Approach to Risk Stratification and Therapeutic Management

Mitral valve prolapse (MVP) is the most common valvular disease with a prevalence of 2%. It has generally a benign course; however, recent findings suggested an association between MVP and complex arrhythmias and eventually cardiac arrest and for this reason, it is also called arrhythmogenic MVP. Subjects who experience this complication are in general young women, with thickened mitral leaflets or bileaflet prolapse not necessarily associated with severe mitral regurgitation (MR). The nature of the relation between MVP and cardiac arrest is not clearly understood. Actually, the challenging task is to find the cluster of prognostic factors including T-wave inversion, polymorphic premature ventricular contractions, bileaflet prolapse, MR severity, but most importantly, those parameters of hypercontractility, mitral annulus disjunction (MAD), and myocardial fibrosis using a multimodality approach. Transthoracic echocardiography is the first-line imaging modality for the diagnosis of MVP, but also for detecting MAD and hypercontractility, followed by cardiac magnetic resonance for tissue characterization and detection of myocardial and papillary muscle fibrosis, using either late gadolinium enhancement (at the basal segment of the inferolateral wall and papillary muscles) (macro-fibrosis), or diffuse fibrosis by T1 mapping (native and post contrast T1). Moreover, there are also preliminary data on positron emission tomography utilizing 18F-fluorodeoxyglucose as a tool for providing evidence of early myocardial inflammation. The objective of this review article is to provide the clinician with an overview and a practical clinical approach to MVP for risk stratification and treatment guidance.