Morphofunctional Abnormalities of Mitral Annulus and Arrhythmic Mitral Valve Prolapse

Circ Cardiovasc Imaging. 2016 Aug;9(8):e005030. doi: 10.1161/CIRCIMAGING.116.005030.

Abstract

Background: Arrhythmic mitral valve prolapse (MVP) is characterized by myxomatous leaflets and left ventricular (LV) fibrosis of papillary muscles and inferobasal wall. We searched for morphofunctional abnormalities of the mitral valve that could explain a regional mechanical myocardial stretch.

Methods and results: Thirty-six (27 female patients; median age: 44 years) arrhythmic MVP patients with LV late gadolinium enhancement on cardiac magnetic resonance and no or trivial mitral regurgitation, and 16 (6 female patients; median age: 40 years) MVP patients without LV late gadolinium enhancement were investigated by morphofunctional cardiac magnetic resonance. Mitral annulus disjunction (median: 4.8 versus 1.8 mm; P<0.001), end-systolic mitral annular diameters (median: 41.2 versus 31.5; P=0.004) and end-diastolic mitral annular diameters (median: 35.5 versus 31.5; P=0.042), prevalence of posterior systolic curling (34 [94%] versus 3 [19%]; P<0.001), and basal to mid LV wall thickness ratio >1.5 (22 [61%] versus 4 [25%]; P=0.016) were higher in MVP patients with late gadolinium enhancement than in those without. A linear correlation was found between mitral annulus disjunction and curling (R=0.85). A higher prevalence of auscultatory midsystolic click (26 [72%] versus 6 [38%]; P=0.018) was also noted. Histology of the mitral annulus showed a longer mitral annulus disjunction in 50 sudden death patients with MVP and LV fibrosis than in 20 patients without MVP (median: 3 versus 1.5 mm; P<0.001).

Conclusions: Mitral annulus disjunction is a constant feature of arrhythmic MVP with LV fibrosis. The excessive mobility of the leaflets caused by posterior systolic curling accounts for a mechanical stretch of the inferobasal wall and papillary muscles, eventually leading to myocardial hypertrophy and scarring. These mitral annulus abnormalities, together with auscultatory midsystolic click, may identify MVP patients who would need arrhythmic risk stratification.

Keywords: gadolinium; mitral valve; mitral valve annulus; mitral valve prolapse; papillary muscles.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Arrhythmias, Cardiac / complications*
  • Arrhythmias, Cardiac / diagnostic imaging
  • Arrhythmias, Cardiac / mortality
  • Arrhythmias, Cardiac / physiopathology
  • Biopsy
  • Contrast Media / administration & dosage
  • Death, Sudden, Cardiac / etiology
  • Echocardiography
  • Electrocardiography, Ambulatory
  • Female
  • Fibrosis
  • Heart Ventricles / diagnostic imaging
  • Heart Ventricles / physiopathology
  • Humans
  • Hypertrophy, Left Ventricular / diagnostic imaging
  • Hypertrophy, Left Ventricular / etiology*
  • Hypertrophy, Left Ventricular / mortality
  • Hypertrophy, Left Ventricular / physiopathology
  • Linear Models
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Mitral Valve / diagnostic imaging
  • Mitral Valve / physiopathology*
  • Mitral Valve Prolapse / diagnostic imaging
  • Mitral Valve Prolapse / etiology*
  • Mitral Valve Prolapse / mortality
  • Mitral Valve Prolapse / physiopathology
  • Papillary Muscles / diagnostic imaging
  • Papillary Muscles / physiopathology
  • Prognosis
  • Risk Factors
  • Ventricular Function, Left
  • Young Adult

Substances

  • Contrast Media