363 TRICUSPID ANNULUS DISJUNCTION: THE MISSING PIECE IN THE ARRHYTHMIC MITRAL VALVE PROLAPSE?


 
 
 Arrhythmic mitral valve prolapse (MVP) is characterized by left ventricular (LV) fibrosis, due to an excessive myocardial stretch on the LV basal-mid inferolateral wall. Mitral annulus disjunction (MAD) and curling are common findings in arrhythmic MVP patients, thus representing the excessive traction of mitral apparatus on myocardium. Cardiac magnetic resonance (CMR) demonstrated to clearly identify these typical morpho-functional alterations, as well as LV fibrosis, in MVP patients. The involvement of right-sided annulus disease recently emerged as an interesting missing piece in the natural history of MVP patients. However, its role in a population of arrhythmic MVP patients in absence of significant mitral regurgitation (MR) has not been evaluated.
 
 
 
 The primary aim of the study was to evaluate the prevalence and the role of tricuspid annulus disjunction (TAD) in the arrhythmic MVP patients. Secondly, we evaluated the role of TAD in the prevalence and severity of the common morpho-functional alterations of MVP, MAD and curling.
 
 
 
 Consecutive MVP patients with normal systolic function and without significant MR, referred for palpitations, were enrolled. Morpho-biventricular evaluations, including MAD and curling assessment, as well as LV fibrosis were evaluated using CMR.
 
 
 
 66 patients met the inclusion criteria (29% male, median age 44 years). TAD was identified in 22 MVP patients (27% male, median age 52 years). No differences for ventricular arrhythmias (p: 0.459) between MVP patients without (n: 44) and with TAD (n: 22) were identified. MVP patients with TAD were older (52 vs 42 years, p: 0.009) and presented reduced biventricular end-diastolic volumes, despite normal, in comparison with those without TAD (left ventricle: 80.5 vs 93.5 ml/m2, p: 0.002; right ventricle: 72.5 vs 85.5 ml/m2, p: 0.018). MAD and curling were more common in patients without TAD (respectively, 25 vs 19, p:0.014 and 24 vs 20, p: 0.002) than in those with TAD. Conversely, MAD and curling are more severe in patients with TAD (respectively, 5.9 vs 4.7 mm and 4 vs 3 mm, both p: 0.034) than in those without TAD. No differences for LGE distribution were identified in the two groups (p: 0.062).
 
 
 
 In arrhythmic MVP patients, presence of TAD was associated with a great severity of MAD and curling. So, despite uncommon, the contextual presence of TAD and MAD in arrhythmic MVP patients suggests a more severe biannular disease, characterized by an increased biventricular myocardial stretch. Conversely to MAD, TAD wasn't associated with ventricular arrhythmias. Thus, its role in ventricular arrhythmogenesis in MVP patients appeared limited.
