Mechanisms of atrial mitral regurgitation: insights using 3D transoesophageal echo.

Abstract

AIMS:

Functional mitral regurgitation (FMR) is a consequence of mitral annular enlargement, leaflet tethering and reduced co-aptation. The importance of the left atrium (LA) as a cause of mitral regurgitation (MR) is less clear. We applied a co-aptation index using three-dimensional (3D) transoesophageal echocardiography to FMR and MR secondary to LA dilatation (atrial mitral regurgitation, AMR).

METHODS AND RESULTS:

Seventy-two patients underwent comprehensive 3D echo studies: FMR (n = 19); AMR (n = 33); and 20 controls. We recorded: LV size and function; LA dimensions; mitral annular area (MVA); and leaflet area in early and late systole. MVA fractional change was defined: (MVA late systole - MVA early systole)/MVA late systole × 100%; the co-aptation index was defined: (leaflet area early systole - leaflet area late systole)/leaflet area early systole × 100%. Despite normal LV size and function in AMR, MVA was increased similarly to FMR (AMR 12.86 cm(2) vs. FMR 12.33 cm(2), P = ns; both P < 0.01 vs. controls 8.83 cm(2)), and MVA fractional change similarly reduced (AMR 5.1% vs. FMR 6.3%; P = ns; both P < 0.001 vs. controls 14.6%). The co-aptation index was reduced in both MR groups (FMR 6.6% vs. AMR 7.0%, P = ns; both P < 0.001 vs. controls 19.6%). After multivariate analysis, the co-aptation index (χ(2) = 41.2) and MVA fractional change (χ(2) = 22.1) remained the strongest predictors of MR (both P < 0.001 for the model). A co-aptation index of ≤13% was 96% sensitive and 90% specific for the presence of MR.

CONCLUSION:

LA dilatation leads to MVA enlargement, reduced leaflet co-aptation and MR even without LV dilatation. A co-aptation index describes this in vivo. This work provides insights into the mechanism of AMR.

• Authors: Liam Ring, David P Dutka, Francis C Wells, Simon P Fynn, Leonard M Shapiro, Bushra S Rana
• Journal: European heart journal. Cardiovascular Imaging (Eur Heart J Cardiovasc Imaging) Vol. 15 Issue 5 Pg. 500-8 (May 2014) ISSN: 2047-2412 [Electronic] England
• PMID: 24145456 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Topics

• Aged
• Atrial Fibrillation (diagnostic imaging, physiopathology)
• Case-Control Studies
• Echocardiography, Three-Dimensional
• Echocardiography, Transesophageal
• Female
• Heart Atria (diagnostic imaging, physiopathology)
• Humans
• Image Interpretation, Computer-Assisted
• Male
• Middle Aged
• Mitral Valve Insufficiency (diagnostic imaging, physiopathology)