MITRAL VALVE PROLAPSE PHENOTYPES ASSOCIATED WITH SUDDEN CARDIAC DEATH

Description and prevalence of ventricular mitral annular disjunction: variation of normality or pathological variant?

INTRODUCTION AND OBJECTIVES

The aim of this study was to investigate a new variation of the atrial wall-mitral annulus-ventricular wall junction along the mural mitral leaflet and commissures: the ventricular mitral annular disjunction (v-MAD). This new variant is characterized by spatial displacement of the mitral leaflet hinge line by more than 2mm toward the left ventricle.

METHODS

We examined a cohort of autopsied human hearts (n=224, 21.9% females, 47.9±17.6 years) from patients without known cardiovascular disease to identify the presence of v-MAD.

RESULTS

More than half (57.1%) of the hearts showed no signs of MAD in the mural mitral leaflet or mitral commissures. However, v-MAD was found in 23.6% of cases, located within 20.1% of mural leaflets, 2.2% in superolateral commissures, and 1.3% in inferoseptal commissures. V-MAD was not uniformly distributed along the mitral annulus circumference, with the most frequent site being the P2 scallop (19.6% of hearts). The v-MAD height was significantly greater in mural leaflets than in commissures (4.4 mm±1.2 mm vs 2.1 mm±0.1 mm; P<.001). No specific variations in mitral valve morphology or anthropometrical features of donors were associated with the presence or distribution of v-MADs. Microscopic examinations revealed the overlap of the thin layer of atrial myocardium over ventricular myocardium in areas of v-MAD.

CONCLUSIONS

Our study is the first to present a detailed definition and morphometric description of v-MAD. Further studies should focus on the clinical significance of v-MAD to elucidate whether it represents a benign anatomical variant or a significant clinical anomaly.

Morphology of the mural and commissural atrioventricular junction of the mitral valve

OBJECTIVE

This study investigates mitral annular disjunctions (MAD) in the atrial wall-mitral annulus-ventricular wall junction along the mural mitral leaflet and commissures.

METHODS

We examined 224 adult human hearts (21.9% females, 47.9±17.6 years) devoid of cardiovascular diseases (especially mitral valve disease). These hearts were obtained during forensic medical autopsies conducted between January 2018 and June 2021. MAD was defined as a spatial displacement (≥2 mm) of the leaflet hinge line towards the left atrium. We provided a detailed morphometric analysis (disjunction height) and histological examination of MADs.

RESULTS

MADs were observed in 19.6% of all studied hearts. They appeared in 12.1% of mural leaflets. The P1 scallop was the primary site for disjunctions (8.9%), followed by the P2 scallop (5.4%) and P3 scallop (4.5%). MADs were found in 9.8% of all superolateral and 5.8% of all inferoseptal commissures. The average height for leaflet MADs was 3.0±0.6 mm, whereas that for commissural MADs was 2.1±0.5 mm (p<0.0001). The microscopical arrangement of MADs in both the mural leaflet and commissures revealed a disjunction shifted towards left atrial aspect, filled with connective tissue and covered by elongated valve annulus. The size of the MAD remained remarkably uniform and showed no correlation with other anthropometric factors (all p>0.05).

CONCLUSIONS

In the cohort of the patients with healthy hearts, MAD is present in about 20% of all studied hearts. The MADs identified tend to be localised, confined to a single scallop. Moreover, MADs in the commissures are notably smaller than those in the mural leaflet.

High-risk phenotypes of arrhythmic mitral valve prolapse: a systematic review and meta-analysis

BACKGROUND

Mitral valve prolapse (MVP) is associated with aggravated risk of ventricular tachycardia (VT), ventricular fibrillation (VF) and sudden cardiac death (SCD). There is a lack of specific guideline recommendation regarding risk stratification and management, despite multiple proposed high-risk phenotypes. We performed systematic review and meta-analysis to evaluate high-risk phenotypes for malignant arrhythmias in patients with MVP.

METHODS

We comprehensively searched the databases of MEDLINE, SCOPUS, and EMBASE from inception to April 2023. Included studies were cohort and case-control comparing between MVP patients with and without VT, VF, cardiac arrest, ICD placement, or SCD. Data from each study were combined using the random-effects. Pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated.

RESULTS

Nine studies from 1985 to 2023 were included involving 2,279 patients with MVP. We found that T-wave inversion (OR 2.52; 95% CI: 1.90-3.33; p < 0.001), bileaflet involvement (OR 2.28; 95% CI: 1.69-3.09; p < 0.001), late gadolinium enhancement (OR 17.05; 95% CI: 3.41-85.22; p < 0.001), mitral annular disjunction (OR 3.71; 95% CI: 1.63-8.41; p < 0.002), and history of syncope (OR 6.96; 95% CI: 1.05-46.01; p = 0.044), but not female (OR 0.96; 95% CI: 0.46-2.01; p = 0.911), redundant leaflets (OR 4.30; 95% CI: 0.81-22.84; p = 0.087), or moderate-to-severe mitral regurgitation (OR 1.24; 95% CI: 0.65-2.37; p = 0.505), were associated with those events.

CONCLUSION

Bileaflet prolapse, T-wave inversion, mitral annular disjunction, late gadolinium enhancement, and history of syncope are high-risk phenotypes among population with MVP. Further research is needed to validate the risk stratification model and justify the role of primary prophylaxis against malignant arrhythmias.

Mitral Annular Disjunction: Associated Pathologies and Clinical Consequences

PURPOSE OF REVIEW

To provide an overview of mitral annular disjunction (MAD) and to discuss important challenges in diagnosis and management of MAD.

RECENT FINDINGS

MAD has regained interest in the context of sudden cardiac death (SCD) in patients with mitral valve prolapse (MVP), coined as the "arrhythmic" MVP syndrome. In addition, MAD in isolation was recently suggested to be associated with severe arrhythmia and SCD. There is a lack of consensus on the definition of MAD and the imaging modality to be used for diagnosing MAD, and the therapeutic implications of MAD remain uncertain. Furthermore, the exact mechanism underlying the association of MAD with SCD remains largely unexplored.

Prevalence and extent of mitral annular disjunction in structurally normal hearts: comprehensive 3D analysis using cardiac computed tomography

AIMS

Mitral annular disjunction is fibrous separation between the attachment of the posterior mitral leaflet and the basal left ventricular myocardium initially described in dissected hearts. Currently, it is commonly evaluated by echocardiography, and potential relationships with mitral valve prolapse and ventricular arrhythmia have been suggested. However, controversy remains as its prevalence and extent have not been fully elucidated in normal living subjects.

METHODS AND RESULTS

Systolic datasets of cardiac computed tomography obtained from 98 patients (mean age, 69.1 ± 12.6 years; 81% men) with structurally normal hearts were assessed retrospectively. Circumferential extent of both mitral leaflets and disjunction was determined by rotating orthogonal multiplanar reconstruction images around the central axis of the mitral valvar orifice. Distribution angle within the circumference of the mitral valvar attachment and maximal height of disjunction were quantified. In total, 96.0% of patients demonstrated disjunction. Average distribution angles of the anterior and posterior mitral leaflets were 91.3 ± 9.4° and 269.8 ± 9.7°, respectively. Average distribution angle of the disjunction was 105.1 ± 49.2°, corresponding to 39.0 ± 18.2% of the entire posterior mitral valvar attachment. Median value of the maximal height of disjunction was 3.0 (1.5-7.0) mm. Distribution prevalence map of the disjunction revealed characteristic double peaks, with frequent sites of the disjunction located at the anterior to antero-lateral and inferior to infero-septal regions.

CONCLUSION

Mitral annular disjunction is a rather common finding in the normal adult heart with bimodal distribution predominantly observed involving the P1 and P3 scallops of the posterior mitral leaflet.