Prevalence of Mitral Annulus Disjunction and Mitral Valve Prolapse in Patients With Idiopathic Ventricular Fibrillation

The Dutch Idiopathic Ventricular Fibrillation Registry: progress report on the quest to identify the unidentifiable

BACKGROUND

Idiopathic ventricular fibrillation (iVF) is a rare cause of sudden cardiac arrest and, by definition, a diagnosis of exclusion. Due to the rarity of the disease, previous and current studies are limited by their retrospective design and small patient numbers. Even though the incidence of iVF has declined owing to the identification of new disease entities, an important subgroup of patients remains.

AIM

To expand the existing Dutch iVF Registry into a large nationwide cohort of patients initially diagnosed with iVF, to reveal the underlying cause of iVF in these patients, and to improve arrhythmia management.

METHODS

The Dutch iVF Registry includes sudden cardiac arrest survivors with an initial diagnosis of iVF. Clinical data and outcomes are collected. Outcomes include subsequent detection of a diagnosis other than 'idiopathic', arrhythmia recurrence and death. Non-invasive electrocardiographic imaging is used to investigate electropathological substrates and triggers of VF.

RESULTS

To date, 432 patients have been included in the registry (median age at event 40 years (interquartile range 28-52)), 61% male. During a median follow-up of 6 (2-12) years, 38 patients (9%) received a diagnosis other than 'idiopathic'. Eleven iVF patients were characterised with electrocardiographic imaging.

CONCLUSION

The Dutch iVF Registry is currently the largest of its kind worldwide. In this heterogeneous population of index patients, we aim to identify common functional denominators associated with iVF. With the implementation of non-invasive electrocardiographic imaging and other diagnostic modalities (e.g. echocardiographic deformation, cardiac magnetic resonance), we advance the possibilities to reveal pro-fibrillatory substrates.

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.

Sudden Cardiac Arrest in a Youth with Multiple Arrhythmic Substrates

Background

Mitral valve prolapse (MVP) is a common condition with an estimated prevalence of 1-3%, in which there is systolic displacement of a morphologically redundant mitral valve towards the left atrium. Mitral annular disjunction (MAD) is a separation of the MV attachment with the left ventricle, with hypermobility of the leaflets, and with systolic "curling" of the basal LV (left ventricle) myocardium. It is frequently associated with MVP and may confer an increased arrhythmic risk. Case Description. A 28-year-old male had ventricular fibrillation leading to out-of-hospital cardiac arrest, which was successfully resuscitated. His coronary arteries were unobstructed on invasive coronary angiography. Transthoracic echocardiogram (TTE) demonstrated MAD, confirmed by cardiac magnetic resonance (CMR) imaging and transoesophageal echocardiogram (TOE). The LV was severely dilated with reduced EF (ejection fraction), and the QTc interval was also prolonged. His father had died suddenly aged 50 years.

Conclusions

This report describes the clinical dilemma of identifying and treating a patient with multiple potential causes of cardiac arrest. Despite being relatively common, the clinical significance of MAD is still uncertain and the extent to which it may be linked with complications such as ventricular arrhythmias and sudden cardiac death. MAD appears to confer an increased risk of ventricular arrhythmias, particularly when associated with MVP, particularly nonsustained VT.

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

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.

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: Risk Assessment and Management

Arrhythmic mitral valve prolapse (MVP) has gained great interest recently because of the increasing recognition of its potential role in unexplained cardiac arrest. Although evidence has accumulated to show the association of arrhythmic MVP (AMVP) with sudden cardiac death (SCD), risk stratification and management remain unclear. Physicians are faced with the challenges of screening for AMVP among MVP patients and the dilemma of when and how to intervene to prevent SCD in these patients. In addition, there is little guidance to help approach MVP patients who present with an otherwise unexplained cardiac arrest to know whether MVP was the primary cause of cardiac arrest or just an innocent bystander. Herein we review the epidemiology and definition of AMVP, the risk and mechanisms of SCD, and summarize the clinical evidence behind risk markers of SCD and therapeutic interventions that could potentially prevent it. We also propose an algorithm that provides guidance as to how to screen for AMVP and what therapeutic interventions to use. Last, we propose a diagnostic algorithm for approaching patients with otherwise unexplained cardiac arrest who are shown to have MVP.

Outcomes in Dutch DPP6 risk haplotype for familial idiopathic ventricular fibrillation: a focused update

BACKGROUND

The genetic risk haplotype DPP6 has been linked to familial idiopathic ventricular fibrillation (IVF), but the associated long-term outcomes are unknown.

METHODS

DPP6 risk haplotype-positive family members (DPP6 cases) and their risk haplotype-negative relatives (DPP6 controls) were included. Clinical follow-up data were collected through March 2023. Implantable cardioverter-defibrillator (ICD) indication was divided in primary or secondary prevention. Cumulative survival and event rates were calculated.

RESULTS

We included 327 DPP6 cases and 315 DPP6 controls. Median follow-up time was 9 years (interquartile range: 4-12). Of the DPP6 cases, 129 (39%) reached the composite endpoint of appropriate ICD shock, sudden cardiac arrest or death, at a median age of 45 years (range: 15-97). Median overall survival was 83 years and 87 years for DPP6 cases and DPP6 controls, respectively (p < 0.001). In DPP6 cases, median overall survival was shorter for males (74 years) than females (85 years) (p < 0.001). Of the DPP6 cases, 97 (30%) died, at a median age of 50 years. With a prophylactic ICD implantation advise based on risk haplotype, sex and age, 137 (42%) of DPP6 cases received an ICD, for primary prevention (n = 109) or secondary prevention (n = 28). In the primary prevention subgroup, 10 patients experienced a total of 34 appropriate ICD shocks, and there were no deaths during follow-up. DPP6 cases with a secondary prevention ICD experienced a total of 231 appropriate ICD shocks.

CONCLUSION

Patients with the DPP6 risk haplotype, particularly males, are at an increased risk of IVF and sudden cardiac death. Using a risk stratification approach based on risk haplotype, sex and age, a substantial proportion of patients with a primary prevention ICD experienced appropriate ICD shocks, showing the benefit of prophylactic ICD implantation with this strategy.

Three-dimensional transoesophageal echocardiography: how to use and when to use-a clinical consensus statement from the European Association of Cardiovascular Imaging of the European Society of Cardiology

Three-dimensional transoesophageal echocardiography (3D TOE) has been rapidly developed in the last 15 years. Currently, 3D TOE is particularly useful as an additional imaging modality for the cardiac echocardiographers in the echo-lab, for cardiac interventionalists as a tool to guide complex catheter-based procedures cardiac, for surgeons to plan surgical strategies, and for cardiac anaesthesiologists and/or cardiologists, to assess intra-operative results. The authors of this document believe that acquiring 3D data set should become a 'standard part' of the TOE examination. This document provides (i) a basic understanding of the physic of 3D TOE technology which enables the echocardiographer to obtain new skills necessary to acquire, manipulate, and interpret 3D data sets, (ii) a description of valvular pathologies, and (iii) a description of non-valvular pathologies in which 3D TOE has shown to be a diagnostic tool particularly valuable. This document has a new format: instead of figures randomly positioned through the text, it has been organized in tables which include figures. We believe that this arrangement makes easier the lecture by clinical cardiologists and practising echocardiographers.

Sex Differences in Epidemiology, Morphology, Mechanisms, and Treatment of Mitral Valve Regurgitation

Sex-related disparities have been recognized in incidence, pathological findings, pathophysiological mechanisms, and diagnostic pathways of non-rheumatic mitral regurgitation. Furthermore, access to treatments and outcomes for surgical and interventional therapies among women and men appears to be different. Despite this, current European and US guidelines have identified common diagnostic and therapeutic pathways that do not consider patient sex in decision-making. The aim of this review is to summarize the current evidence on sex-related differences in non-rheumatic mitral regurgitation, particularly regarding incidence, imaging modalities, surgical-derived evidence, and outcomes of transcatheter edge-to-edge repair, with the goal of informing clinicians about sex-specific challenges to consider when making treatment decisions for patients with mitral regurgitation.

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.