Mechanism of higher incidence of ischemic mitral regurgitation in patients with inferior myocardial infarction: Quantitative analysis of left ventricular and mitral valve geometry in 103 patients with prior myocardial infarction

Dr Kumanohoso and colleagues

Leaflet-tethering hypothesis for the mechanism of mitral leaflet tenting and functional MR: left, normal leaflet tethering in a normal subject; right, augmented leaflet tethering resulting in apical displacement of the mitral leaflets and MR caused by LV dilation, systolic LV regional wall motion abnormalities, or both. MLT, Mitral leaflet tenting; LA, left atrium; Ao, aorta; AML, anterior mitral leaflet; PML, posterior mitral leaflet.

Methods to measure (1) the mitral annular area from 2 diameters in apical views, (2) the mitral leaflet-tenting area between the mitral leaflets and a line connecting mitral annular hinge points in the midsystolic apical 4-chamber view (dashed area shown in the left panel), and (3) leaflet-tethering lengths between anterior or posterior PM tips and contralateral anterior mitral annulus (ℓ₁ and ℓ₂). LV, Left ventricle; LA, left atrium; RV, right ventricle; RA, right atrium.

Bar graphs showing differences in mitral leaflet-tenting area, percentage of MR jet area, and anterior or posterior PM-tethering distances between patients with anterior and inferior infarction. NS, Not significant.

Scattergraphs showing relationships between mitral leaflet-tenting area and its determinants. Multiple stepwise regression analysis identified the increase in posterior PM-tethering distance/BSA as an independent contributing factor to the mitral leaflet-tenting area, along with mitral annular area/BSA and inferior MI location.

Scattergraphs showing relationships between percentage of MR jet area and its determinants. Multiple stepwise regression analysis identified the increase in posterior PM-tethering distance/BSA as an independent contributing factor to the percentage of MR jet area, along with LV end-diastolic volume/BSA, inferior MI location, and mitral annular area.