Mitral annular dilation

Last revised by Joachim Feger on 17 Dec 2021

Mitral annular dilation refers to an increased mitral annulus in relation to the size of the mitral valvular leaflets and is a potential cause for mitral regurgitation.

Mitral annular dilation is seen in the following clinical conditions 1-3:

Mitral annular dilation can be found as a contributing factor of mitral regurgitation and can be found in the Carpentier types I or IIIb depending on whether it is associated with left atrial or left ventricular dilation 3. If isolated it is usually associated with compensatory leaflet growth, 

Causes of mitral annular dilation include the following 1,2

The following cut-off values are considered criteria for annular dilation 1,2

  • systolic anteroposterior diameter >35 mm (parasternal long axis) 
  • ratio of the systolic annular diameter/diastolic anterior leaflet length >1.3

The following end-systolic annular measurements are considered abnormal according to a study (according to image plane) 4

  • 2-chamber view: >2.5 cm/m2 (male), >2.5 cm/m2 (female)
  • 3-chamber view: >2.2 cm/m2 (male), >2.3 cm/m2 (female)
  • 4-chamber view: >2.3 cm/m2 (male), >2.4 cm/m2 (female)

The radiological report should include a description of the following features:

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