Different influences of left ventricular remodeling on anterior and posterior mitral leaflet tethering.

BACKGROUND  Different influences of left ventricular (LV) remodeling on anterior and posterior mitral leaflet (AML and PML) tethering in ischemic mitral regurgitation (MR) has not been fully investigated. We hypothesized that progressive outward displacement of papillary muscles, including posterior vector, may cause greater tethering to PML compared to AML. METHODS AND RESULTS  In 79 patients with LV ejection fraction <50% and 20 controls, LV sphericity, AML and PML tethering angles, apical and posterior displacement of coaptation, mitral annular area, and severity of MR (vena contracta width) were measured using 3-D echocardiography. To examine different influences of LV remodeling on AML and PML tethering, interaction between AML/PML and LV sphericity was tested using multiple regression analysis. Both AML and PML tethering significantly increased with increased LV sphericity (r=0.59 and 0.65, P<0.001). Multiple regression yielded a significant interaction term between AML vs. LV sphericity and PML vs. LV sphericity (t=3.69, P<0.001), indicating greater influence from LV remodeling on PML compared to that for the AML. Multivariate analysis demonstrated independent contributions to MR severity from PML tethering primarily along with posterior and apical displacement of coaptation. CONCLUSIONS  LV remodeling augments tethering of both AML and PML, with greater influence on PML.