Mitral Annular Disjunction Research Articles

Substrate Characterization and Outcomes of Catheter Ablation of Ventricular Arrhythmias in Patients With Mitral Annular Disjunction.

Mitral annular disjunction (MAD) has recently been recognized as an arrhythmogenic entity. Data on the electrophysiological substrate as well as the outcomes of catheter ablation of ventricular arrhythmias in patients with MAD is limited. Forty patients with MAD (mean age 47±15 years; 70% female) underwent catheter ablation for ventricular arrhythmias. Detailed clinical, electrocardiographic, cardiac imaging, and procedural data were collected. Clinical outcomes were compared between patients who had substrate modification in the MAD area and those who did not. Twenty-three (57.5%) patients had ablation for premature ventricular contractions, 10 (25%) patients for sustained ventricular tachycardia, and 7 (17.5%) patients for premature ventricular contraction-triggered ventricular fibrillation. Mean end-systolic MAD length was 10.58±3.49 mm on transthoracic echocardiography. Seventeen (42.5%) patients had preprocedural cardiac magnetic resonance imaging, and 5 (29%) patients had late gadolinium enhancement. Among the 18 (45%) patients who had abnormal local electrograms (low voltage, long-duration, fractionated, isolated mid-diastolic potentials) during electroanatomical mapping, 10 (25%) patients had abnormal electrograms in the anterolateral mitral annulus and/or MAD area. Substrate modification was performed in 10 (25%) patients. Catheter ablation was acutely successful in 36 (90%) patients (elimination of premature ventricular contraction or noninducibility of ventricular tachycardia). After a median follow-up duration of 54.08 (interquartile range, 10.67-89.79) months, premature ventricular contraction burden decreased from a median of 9.75% (interquartile range, 3.25-14) before the ablation to a median of 4% (interquartile range, 1-7.75) after the ablation (P=0.03 [95% CI, 0.055-6.5]). Eight (20.5%) patients had repeat ablation for ventricular arrhythmias. Substrate modification of the MAD was associated with a trend toward lower rates of repeat ablation (0% versus 26.7%; P=0.16). Patients with MAD have a complex arrhythmogenic substrate, and catheter ablation is effective in reducing recurrence of ventricular arrhythmias. Substrate mapping and ablation may be considered in these patients.

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 Annulus Disjunction and Arrhythmic Mitral Valve Prolapse: Emerging Role of Cardiac Magnetic Resonance Imaging in the Workup.

Mitral valve prolapse is a commonly described entity with a highly variable and benign course. However, it is associated with ventricular arrhythmias and sudden cardiac death in a small subset of patients. Recent studies have yielded insight into myocardial mechanics and the causation of ventricular arrhythmias in these groups of patients. Mitral annular disjunction (MAD) characterized by detachment of mitral annulus from left ventricular myocardium is associated with morphological and functional remodeling of the left ventricular myocardium. Resultant fibrosis acts as a substrate of ventricular arrhythmia and sudden cardiac death. We present two such cases of arrhythmic mitral valve prolapse associated with MAD. Cardiac magnetic resonance imaging provides excellent morphological information and also helps in the assessment of fibrosis.

Transthoracic echocardiography for arrhythmic mitral valve prolapse: Phenotypic characterization as first step.

Mitral valve prolapse (MVP) is the most frequent valvulopathy with a prevalence of 1.2%-2.4% in general population and it is characterized by a benign course. Although it can be associated with some complications, ventricular arrhythmias (VA) and sudden cardiac death (SCD) as ultimate expressions, are the most worrying. The estimated risk of SCD in MVP is between 0.2% and 1.9% per year including both MVP patients with left ventricular (LV) dysfunction due to severe MR and MVP patients without significant MR. The latter ones constitute a particular phenotype called "malignant MVP" characterized by bileaflet myxomatous prolapse, ECG repolarization abnormalities and complex VAs (c-VAs) with polymorphic/right bundle branch block morphology (RBBB) and LV fibrosis of the papillary muscles (PMs) and inferobasal wall secondary to mechanical stretching visualized as late gadolinium enhancement (LGE) areas by cardiac magnetic resonance (CMR). In MVP, the first diagnostic approach is transthoracic echocardiography (TTE) that defines the presence of mitral annular disjunction (MAD) which seems to be associated with "arrhythmic MVP" (AMVP). From an ECG point of view, AMVP is characterized by frequent premature ventricular contractions (PVCs) arising from one or both PMs, fascicular tissue, and outflow tract, as well as by T-wave inversion in the inferolateral leads. The aim of the present paper is to describe TTE red flags that could identify MVP patients at high risk to develop complex arrhythmias as supported by the corresponding findings of LGE-CMR and anatomy studies. TTE could be a co-partner in phenotyping high-risk arrhythmic MVP patients.

Mitral annular disjunction: A case series and review of the literature.

Mitral annular disjunction (MAD) is an abnormal displacement of the mitral valve leaflet onto the left atrial wall and is commonly found in patients with mitral valve prolapse (MVP). The diagnosis is usually made by transthoracic echocardiography (TTE) although findings can be subtle and further cardiac imaging may be necessary. MAD has been associated with a risk of malignant ventricular arrhythmias and sudden cardiac death, therefore recognition of this diagnosis and risk stratification are highly important. In this review, we will discuss the diagnosis, clinical implications, risk stratification and management of MAD based upon currently available literature, as well as provide a series of cases showing the heterogeneity in presentation and our experience with management of this rare but potentially fatal entity.

EHRA expert consensus statement on arrhythmic mitral valve prolapse and mitral annular disjunction complex in collaboration with the ESC Council on valvular heart disease and the European Association of Cardiovascular Imaging endorsed cby the Heart Rhythm Society, by the Asia Pacific Heart Rhythm Society, and by the Latin American Heart Rhythm Society.

EHRA expert consensus statement on arrhythmic mitral valve prolapse and mitral annular disjunction complex in collaboration with the ESC Council on valvular heart disease and the European Association of Cardiovascular Imaging endorsed cby the Heart Rhythm Society, by the Asia Pacific Heart Rhythm Society, and by the Latin American Heart Rhythm Society.

The influence of chest wall conformation on myocardial strain parameters in a cohort of mitral valve prolapse patients with and without mitral annular disjunction.

To evaluate the possible influence of chest wall conformation on myocardial strain parameters in a cohort of mitral valve prolapse (MVP) patients with and without mitral annular disjunction (MAD). All consecutive middle-aged patients with MVP referred to our Outpatient Cardiology Clinic for performing two-dimensional (2D) transthoracic echocardiography (TTE) as part of work up for primary cardiovascular prevention between March 2018 and May 2022, were included into the study. All patients underwent clinic visit, physical examination, modified Haller index (MHI) assessment (the ratio of chest transverse diameter over the distance between sternum and spine) and conventional 2D-TTE implemented with speckle tracking analysis of left ventricular (LV) global longitudinal strain (GLS) and global circumferential strain (GCS). Independent predictors of MAD presence on 2D-TTE were assessed. A total of 93 MVP patients (54.2 ± 16.4 yrs, 50.5% females) were prospectively analyzed. On 2D-TTE, 34.4% of MVP patients had MAD (7.3 ± 2.0mm), whereas 65.6% did not. Compared to patients without MAD, those with MAD had: 1) significantly shorter antero-posterior (A-P) thoracic diameter (13.5 ± 1.2 vs 14.8 ± 1.3cm, p < 0.001); 2) significantly smaller cardiac chambers dimensions; 3) significantly increased prevalence of classic MVP (84.3 vs 44.3%, p < 0.001); 4) significantly impaired LV-GLS (-17.2 ± 1.4 vs -19.4 ± 3.0%, p < 0.001) and LV-GCS (-16.3 ± 4.1 vs -20.4 ± 4.9, p < 0.001), despite similar LV ejection fraction (63.7 ± 4.2 vs 63.0 ± 3.9%, p = 0.42). A-P thoracic diameter (OR 0.25, 95%CI 0.10-0.82), classic MVP (OR 3.90, 95%CI 1.32-11.5) and mitral annular end-systolic A-P diameter (OR 2.76, 95%CI 1.54-4.92) were the main independent predictors of MAD. An A-P thoracic diameter ≤ 13.5cm had 59% sensitivity and 84% specificity for predicting MAD presence (AUC = 0.81). In addition, MAD distance was strongly influenced by A-P thoracic diameter (r = - 0.96) and MHI (r = 0.87), but not by L-L thoracic diameter (r = 0.23). Finally, a strong inverse correlation between MHI and both LV-GLS and LV-GCS was demonstrated in MAD patients (r = - 0.94 and - 0.92, respectively), but not in those without (r = - 0.51 and - 0.50, respectively). A narrow A-P thoracic diameter is strongly associated with MAD presence and is a major determinant of the impairment in myocardial strain parameters in MAD patients, in both longitudinal and circumferential directions.

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

BackgroundIdiopathic ventricular fibrillation (IVF) is diagnosed in patients with ventricular fibrillation of which the origin is not identified after extensive evaluations. Recent studies suggest an association between mitral annulus disjunction (MAD), mitral valve prolapse (MVP), and ventricular arrhythmias. The prevalence of MAD and MVP in patients with IVF in this regard is not well established. We aimed to explore the prevalence of MAD and MVP in a consecutive cohort of patients with IVF compared with matched controls.Methods and ResultsIn this retrospective, multicenter cohort study, cardiac magnetic resonance images from patients with IVF (ie, negative for ischemia, cardiomyopathy, and channelopathies) and age‐ and sex‐matched control subjects were analyzed for the presence of MAD (≥2 mm) and MVP (>2 mm). In total, 72 patients (mean age 39±14 years, 42% women) and 72 control subjects (mean age 41±11 years, 42% women) were included. MAD in the inferolateral wall was more prevalent in patients with IVF versus healthy controls (7 [11%] versus 1 [1%], P=0.024). MVP was only seen in patients with IVF and not in controls (5 [7%] versus 0 [0%], P=0.016). MAD was observed in both patients with (n=4) and without (n=3) MVP.ConclusionsInferolateral MAD and MVP were significantly more prevalent in patients with IVF compared with healthy controls. The authors advocate that evaluation of the mitral valve region deserves extra attention in the extensive screening of patients with unexplained cardiac arrest. These findings support further exploration of the pathophysiological mechanisms underlying a subset of IVF that associates with MAD and MVP.

Mitral Annular Elasticity Determines Severity of Regurgitation in Barlow’s Mitral Valve Disease

Barlow's mitral valve disease with late systolic mitral regurgitation provides diagnostic and therapeutic challenges. The mechanisms of the regurgitation are still unclear. We hypothesized that the onset and the severity of late systolic regurgitation are determined by annulus dynamics and the mechanical stresses imposed by the left ventricle. Ten patients with Barlow's mitral valve disease and mitral annulus disjunction (MAD) were compared with 10 healthy controls. Resting blood pressure was measured, and transthoracic three-dimensional echocardiography was analyzed using a holographic display that allows tracking and measurements of mitral annulus surface area (ASA) throughout the cardiac cycle. A novel annulus elastance index (dASA/dP) was calculated between aortic valve opening and onset of mitral regurgitation. Severity of MAD was quantified as the disjunction index (mm × degree). Leaflet coaptation area was calculated using a finite element model. Peak systolic ASAs in controls and patients were 9.3±0.6 and 21.1±3.1cm², respectively (P&lt;.001). In patients, the ASA increased rapidly during left ventricular ejection, and onset of mitral regurgitation coincided closely with peak upslope of annulus area change (dASA/dt). The finite element model showed a close association between rapid annulus displacement and coaptation area deficit in Barlow's mitral valve disease. Systolic annulus elastance index (0.058±0.036cm²/mm Hg) correlated strongly with disjunction index (r=0.91, P&lt;.0001). Moreover, regurgitation volume showed a positive correlation with systolic blood pressure (r=0.80, P&lt;.01). The present pilot study supports the hypothesis that annulus dilatation may accentuate mitral valve regurgitation in patients with Barlow's mitral valve disease. A novel annulus elastance index may predict the severity of mitral valve regurgitation in selected patients.

Echocardiographic description and outcomes in a heterogeneous cohort of patients undergoing mitral valve surgery with and without mitral annular disjunction: a health service evaluation

BackgroundMitral annular disjunction (MAD) is a structural abnormality characterized by the distinct separation of the mitral valve annulus/left atrium wall and myocardium. Little is known about the significance of MAD in patients requiring mitral valve surgery. This evaluation evaluates the echocardiographic characteristics and patient outcomes for patients with and without MAD who require mitral valve surgery.MethodsAll patients who underwent mitral valve surgery and who had a pre-surgical transthoracic echocardiogram between 2013 and 2020 were included. Patient demographics and clinical outcomes were collected on review of patient electronic records.ResultsA total of 185 patients were included in the analysis of which 32.4% had MAD (average MAD length 8.4 mm). MAD was seen most commonly in patients with mitral valve prolapse and myxomatous mitral valves disease (90% and 60% respectively). In the patients with MAD prior to mitral valve surgery, only 3.9% had MAD post mitral valve surgery. There were no significant difference in the severity of post-operative mitral regurgitation, arrhythmic events or major adverse cardiovascular events in patients with and without MAD.ConclusionsMAD is common in patients who undergo mitral valve surgery. Current surgical techniques are able to correct the MAD abnormality in the vast majority of patients. MAD is not associated with an increased risk of adverse clinical outcomes post mitral valve surgery.

Disjunção do Anel Mitral: Modalidades Diagnósticas, Implicações Clínicas e Evolução Prognóstica

Mitral annulus disjunction (MAD) is an abnormal insertion of the flexion line of the mitral annulus into the atrial wall. The annulus presents a separation (disjunction) between the posterior leaflet–atrial wall junction and the left ventricular myocardial crest.1 MAD was first described more than 30 years ago in an autopsy study and is reportedly related to mitral valve prolapse (MVP) in 92% of cases.2 Since then, several studies have been conducted, and reports on the prevalence of MAD in patients with MVP have varied. Ultimately, it may or may not be associated with mitral regurgitation. Transthoracic echocardiography is part of initial MVP assessment, allowing its diagnosis and the assessment of related complications. As new diagnostic methods emerged, cardiac magnetic resonance imaging and transesophageal echocardiography improved the assessment of this pathology in terms of its diagnosis, extension, and location. However, the phenotypic characteristics of MVP that are more closely associated with MAD remain uncertain mainly due to the limited number of patients in classic studies on the subject. Patients with MAD may develop symptoms related to ventricular arrhythmias, configuring the MAD arrhythmic syndrome, which may progress to sudden death. The literature presents conflicting prognostic data among several studies on the subject from clear diagnostic criteria and best imaging method to be used to treatment and prognosis. This review describes MAD characteristics associated (or not) with valve prolapse to improve the diagnosis and management of this important pathology.

Prevalence and prognostic impact of mitral annular disjunction in patients with STEMI – A cardiac magnetic resonance study

BackgroundMitral annular disjunction (MAD) represents the detachment of the mitral leaflet hinge-point from the ventricular myocardium. Its role in patients with ST-segment-elevation myocardial infarction (STEMI) is unknown. This study aims to investigate the prevalence of MAD by cardiac magnetic resonance imaging (CMR) in STEMI-patients and its association with serious adverse events. MethodsSTEMI-patients (n = 621) underwent CMR 4 days [interquartile range (IQR) 2–5] after percutaneous coronary intervention. Presence and longitudinal extent of MAD were obtained in long-axis cine-images, infarct characteristics in late gadolinium enhancement-images. During a median follow-up time of 366 days (IQR 136–454), patients were observed for the occurrence of major adverse cardiac events (MACE), comprising death, myocardial reinfarction, and congestive heart failure. ResultsOverall, 307 patients (49 %) had MAD. Longitudinal MAD-distance was 4.6 ± 1.7 mm and the P3-segment was affected most frequently (n = 262, 85 % of MAD-patients). MAD-patients had a significantly smaller infarct size, lower prevalence of microvascular obstruction, and intramyocardial hemorrhage as well as a higher ejection fraction (all p < 0.03). During follow-up period, MACE occurred in 52 patients (8 %) and did not show significant difference between patients with and without MAD (7 % vs. 9 %, p = 0.424). Cardiovascular death occurred significantly more often in patients without MAD (n = 10, 3.2 % vs. n = 2, 0.7 %, p = 0.021). ConclusionMAD is a rather common finding in patients presenting with STEMI. Patients with MAD had less severe infarct characteristics, however, they were not more commonly affected by MACE. Further confirmation and longer follow-up intervals are necessary to define the exact role of MAD in STEMI patients.

P101 ARRHYTHMIC MITRAL VALVE PROLAPSE: COULD ELECTROANATOMICAL MAPPING AND CARDIAC MAGNETIC RESONANCE BE GOOD FRIENDS?

Abstract Background There is an increasing awareness of the association between mitral valve prolapse (MVP) and sudden cardiac death (SCD), but risk stratification is still challenging. Mitral annular disjunction (MAD) is a recognized risk factor for arrhythmic complications. A multimodality imaging strategy, including advanced echocardiography, magnetic resonance (CMR) and electromechanical mapping, could improve risk stratification and management by combining anatomical and functional information. Case Review We report a case of a 50–year–old woman without cardiovascular risk factors, complaining for worsening palpitations in the last months. Echocardiogram documented bileaflet MVP with moderate regurgitation, MAD (12 mm in inferolateral wall) and normal ventricular systolic function. 24–hour Holter monitoring revealed a high (13%) premature ventricular complexes burden with ventricular bigeminy and non–sustained ventricular tachycardia. Stress test showed a reduction of the arrhythmias during exercise. CMR confirmed MAD but no late gadolinium enhancement areas were detected. The patient underwent electrophysiological study with electroanatomic mapping (CARTO). The latter revealed multifocal fragmented and delayed low voltage potentials close to the posterior papillary muscle and the posterior anular mitral area, respectively. Both locations were the targets of endoventricular radiofrequency ablation. However, due to her high arrhythmic risk profile the patient implanted a cardioverter defibrillator. Discussion In arrhythmic risk stratification of MVP with MAD, CMR could have technical limitations due to diffuse fibrosis patterns or irregular cardiac rhythm that could undermine a detailed and complete evaluation. Thus, electroanatomical mapping during electrophysiological testing could offer additional and complementary information that could improve risk stratification and further management.

Echocardiographic Assessment of Mitral Annular Disjunction With Cross-Correlation by Computed Tomography and Magnetic Resonance Imaging: A Case Series

Mitral valve (MV) pathology, along with its associated peripheral anatomy, is one of the most common categories of heart disease. Two-dimensional (2D) transthoracic echocardiography (TTE) plays a prominent role in the detection and management of various types MV disease, specifically mitral annular disjunction (MAD). MAD is defined as a structural abnormality of the mitral annulus fibrosus, causing a noticeable gap between the atrial wall-mitral valve junction and the basilar portion of the left ventricular free wall (LV). The integral role that cardiac sonographers play in identifying MAD cannot be underscored, as well as the risk of easily overlooking this unique abnormality. Often associated with mitral valve prolapse (MVP), accurate documentation of MAD amid an echocardiographic study can have positive implications on patient prognosis. This case series highlights the echocardiographic characteristics of MAD, to raise awareness of this often forgotten feature of myxomatous mitral valves, which can indeed cause adverse patient outcomes. It is important to demonstrate correlational features with additional imaging techniques such as magnetic resonance imaging (MRI) and computed tomography (CT).

Arrhythmogenic Mitral Valve Prolapse.

Mitral valve prolapse (MVP) is a common condition present in 1–3% of the population. There has been evidence that a subset of MVP patients is at higher risk of sudden cardiac death. The arrhythmogenic mechanism is related to fibrotic changes in the papillary muscles caused by the prolapsing valve. ECG features include ST-segment depression, T wave inversion or biphasic T waves in inferior leads, and premature ventricular contractions arising from the papillary muscles and the fascicular system. Echocardiography can identify MVP and mitral annular disjunction, a feature that has significant negative prognostic value in MVP. Cardiac MRI is indicated for identifying fibrosis. Patients with high-risk features should be referred for further evaluation. Catheter ablation and mitral valve repair might reduce the risk of malignant arrhythmia. MVP patients with high-risk features and clinically documented ventricular arrhythmia may also be considered for an ICD.

Mitral Annular Disjunction: Pathophysiology, Pro-Arrhythmic Profile and Repair Pearls.

Mitral annular disjunction (MAD) is a structural abnormality defined by a distinct separation of the mitral valve annulus-left atrial wall continuum and the basal aspect of the posterolateral left ventricle. This anomaly is often observed in patients with myxomatous mitral valve prolapse. Importantly, MAD has been strongly associated with serious ventricular arrhythmias and predisposes to sudden cardiac death. Therefore, we have to emphasize the need to diagnose this morphologic and functional abnormality in routine practice in order to facilitate optimal mitral valve repair and minimize patient risks. Nevertheless, clinical knowledge regarding MAD still remains limited. In the present review, we aim to shed light on several aspects of MAD, including distinct anatomical and pathophysiological characteristics, imaging modalities, association with ventricular arrhythmias, and current methods of treatment.

Comparison of Mitral Regurgitant Volume Assessment between Proximal Flow Convergence and Volumetric Methods in Patients with Significant Primary Mitral Regurgitation: An Echocardiographic and Cardiac Magnetic Resonance Imaging Study

Discrepancies have been observed between transthoracic echocardiography (TTE) and cardiac magnetic resonance imaging (CMR) severity grading in primary mitral regurgitation (MR). We sought to compare mitral regurgitant volume (RVol) determined by the TTE proximal flow convergence (proximal isovelocity surface area [PISA]) method and by volumetric methods (TTE and CMR) and to study the relationship between left ventricle (LV) size and RVol obtained by either the PISA or volumetric methods. Two centers prospectively recruited 188 patients with at least moderate to severe primary MR due to prolapse in sinus rhythm who underwent TTE and CMR examinations. Regurgitant volume was estimated by either PISA (PISA-RVol) or volumetric methods (LV total stroke volume-systolic aortic forward outflow volume) using either CMR (CMR-RVol) or TTE (TTE-RVol). The PISA-RVol was weakly correlated with CMR-RVol and TTE-RVol (r=0.29 and 0.30, respectively; P<.001 for both). On multivariable analysis, smaller CMR-left ventricular end-diastolic volume (LVEDV) and absence of mitral annular disjunction independently correlated with increased magnitude of RVol difference between PISA and volumetric methods. While PISA-RVol and LVEDV were unrelated, CMR-RVol and TTE-RVol moderately correlated with LVEDV (r=0.66 and 0.68, respectively; P<.001 for both). In contrast, LVEDV and regurgitant fraction (RVol/LVtotal stroke volume), assessed with either TTE or CMR, were poorly correlated (r=0.17, P=.02; and r=0.12, P=.10, respectively). Mitral RVol values estimated by PISA and volumetric methods are not directly comparable. The expected proportional relationship between volumetric RVol and LV size, which was not observed with PISA-RVol, suggests that PISA-RVol would be inaccurate. Given that RVol assessed with volumetric methods depends on LV size, determination of a unique RVol threshold for severe MR is challenging. In contrast to RVol, calculating regurgitant fraction by volumetric methods allows the quantification of MR severity independently from LV size.

Mitral valve prolapse and mitral annulus disjunction: be aware of a potential arrhythmogenic substrate

Mitral valve prolapse is a relatively common disease with a good overall prognosis. However, in specific clinical and instrumental contexts, patients at high risk of ventricular arrhythmias and sudden cardiac death can be identified. Female sex, history of palpitations or syncope, bi-leaflet myxomatous valve, ECG repolarization abnormalities in the inferior leads, complex ventricular arrhythmias, left ventricular fibrosis detected by cardiac magnetic resonance correlate with a higher risk clinical profile. Additionally, morpho-functional abnormalities of the mitral valve annulus, particularly mitral annulus disjunction, may cause a mechanical stretch at the inferior basal ventricular wall and posterior papillary muscles, predisposing to myocardial fibrosis and arrhythmias. A risk stratification strategy is needed to identify patients with mitral valve prolapse and/or mitral annulus disjunction at high risk of arrhythmias; however, few data are available. Further prospective multicenter studies are warranted, focusing on medical therapy, the role of implantable cardioverter-defibrillators for primary prevention, efficacy of targeted catheter ablation or mitral valve surgery.

MITRAL ANNULAR DISJUNCTION: HOW ACCURATE ARE WE?

MITRAL ANNULAR DISJUNCTION: HOW ACCURATE ARE WE?

Developing a Mechanistic Approach to Sudden Death Prevention in Mitral Valve Prolapse.

Sudden cardiac death (SCD) from ventricular fibrillation (VF) can occur in mitral valve prolapse (MVP) in the absence of other comorbidities including mitral regurgitation, heart failure or coronary disease. Although only a small proportion with MVP are at risk, it can affect young, otherwise healthy adults, most commonly premenopausal women, often as the first presentation of MVP. In this review, we discuss arrhythmic mechanisms in MVP and mechanistic approaches for sudden death risk assessment and prevention. We define arrhythmogenic or arrhythmic MVP (AMVP) as MVP associated with complex and frequent ventricular ectopy, and malignant MVP (MMVP) as MVP with high risk of SCD. Factors predisposing to AMVP are myxomatous, bileaflet MVP and mitral annular disjunction (MAD). Data from autopsy, cardiac imaging and electrophysiological studies suggest that ectopy in AMVP is due to inflammation, fibrosis and scarring within the left ventricular (LV) base, LV papillary muscles and Purkinje tissue. Postulated mechanisms include repetitive injury to these regions from systolic papillary muscle stretch and abrupt mitral annular dysmotility (excursion and curling) and diastolic endocardial interaction of redundant mitral leaflets and chordae. Whereas AMVP is seen relatively commonly (up to 30%) in those with MVP, MVP-related SCD is rare (2–4%). However, the proportion at risk (i.e., with MMVP) is unknown. The clustering of cardiac morphological and electrophysiological characteristics similar to AMVP in otherwise idiopathic SCD suggests that MMVP arises when specific arrhythmia modulators allow for VF initiation and perpetuation through action potential prolongation, repolarization heterogeneity and Purkinje triggering. Adequately powered prospective studies are needed to assess strategies for identifying MMVP and the primary prevention of SCD, including ICD implantation, sympathetic modulation and early surgical mitral valve repair. Given the low event rate, a collaborative multicenter approach is essential.