Mechanism of Recurrent/Persistent Ischemic/Functional mitral regurgitation in the chronic phase after surgical annuloplasty - Importance of augmented posterior leaflet tethering

Background - Surgical annuloplasty can potentially hoist the posterior annulus anteriorly, exaggerate posterior leaflet (PML) tethering, and lead to recurrent ischemic/functional mitral regurgitation (MR). Characteristics of leaflet configurations in late postoperative MR were investigated. Methods and Results - In 30 patients with surgical annuloplasty for ischemic MR and 20 controls, the anterior leaflet (AML) and PML tethering angles relative to the line connecting annuli, posterior and apical displacement of the coaptation and the MR grade were measured by echocardiography before, early after, and late after surgery. Early after surgery, grade of MR and AML tethering generally decreased (P < 0.01), whereas PML tethering significantly worsened (P < 0.01). Nine of the 30 patients showed recurrent/ persistent MR late after surgery. Compared with patients without late MR, those with the MR showed similar reduction in the annular area, significant re- increase in posterior displacement of the coaptation, and progressive worsening in PML tethering (P < 0.05) late after surgery in comparison to the early phase. Both preoperative MR and late postoperative MR were significantly correlated with all tethering variables in univariate analysis. Although apical displacement of the coaptation was the primary determinant of preoperative MR (r(2) = 0.60, P < 0.0001), increased PML tethering was the primary determinant of late MR (r(2) = 0.75, P < 0.0001). Conclusions - Whereas both leaflets tethering is related to preoperative ischemic MR, both leaflets tethering but with predominant contribution from augmented and progressive PML tethering is related to recurrent/ persistent ischemic/ functional MR late after surgical annuloplasty.