title: Role of dyssynchrony on functional mitral regurgitation in patients with idiopathic dilated cardiomyopathy: a comparison study with geometric parameters of mitral apparatus.
abstract: BACKGROUND
  Functional mitral regurgitation (FMR) occurs commonly in patients with dilated cardiomyopathy (DCM). This study was conducted to explore the role of left ventricular (LV) dyssynchrony in developing FMR in patients with DCM in comparison with geometric parameters of the mitral apparatus.
  
  
  METHODS
  Twenty patients without FMR and 33 patients with FMR [effective regurgitant orifice area (ERO) = 0.17 ± 0.10 cm(2)] were enrolled. MR severity was estimated with ERO area. Dyssynchrony indices (DI) were measured using the standard deviations of time to peak myocardial systolic velocity between eight segments. Using real time 3D echocardiography, mitral valve tenting area (MVTa), anterior (APMD) and posterior papillary muscle distances (PPMD), LV sphericity, and tethering angle of anterior (Aα) and posterior leaflets (Pα) were estimated. All geometrical measurements were corrected (c) by the height of each patient.
  
  
  RESULTS
  The patient with FMR had significantly higher cDI, cMVTa, cAPMD and cPPMD, LV sphericity, Aα, and Pα than the patients without FMR (all p < 0.05). With multiple logistic regression analysis, cMVTa (p = 0.017) found to be strongest predictor of FMR development. In patients with FMR, cMVTa (r = 0.868), cAPMD (r = 0.801), cPPMD (r = 0.742), Aα (r = 0.454), LV sphericity (r = 0.452), and DI (r = 0.410) showed significant correlation with ERO. On multivariate regression analysis, cMVTa and cAPMD (p < 0.001, p = 0.022, respectively) remained the strongest determinants of the degree of ERO and cAPMD (p < 0.001) remained the strongest determinant of the degree of cMVTa.
  
  
  CONCLUSIONS
  Displacement of anterior papillary muscle and consequent mitral valve tenting seem to play a major role in developing FMR in DCM, while LV dyssynchrony seems to have no significant role.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Konkuk University College of Medicine, Chungju, Korea.
authors.forename: Woong Gil
authors.initials: WG
authors.lastname: Choi
authors.forename: Soo Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Sang Don
authors.initials: SD
authors.lastname: Park
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Baek
authors.forename: Sung Hee
authors.initials: SH
authors.lastname: Shin
authors.forename: Sung Ill
authors.initials: SI
authors.lastname: Woo
authors.forename: Dae Hyeok
authors.initials: DH
authors.lastname: Kim
authors.forename: Keum Soo
authors.initials: KS
authors.lastname: Park
authors.forename: Woo Hyung
authors.initials: WH
authors.lastname: Lee
authors.forename: Jun
authors.initials: J
authors.lastname: Kwan