title: Mechanism of improvement in mitral regurgitation after cardiac resynchronization therapy.
abstract: OBJECTIVE
  The aim of the current study was to evaluate the relationship between the presence of left ventricular (LV) dyssynchrony at baseline and acute vs. late improvement in mitral regurgitation (MR) after cardiac resynchronization therapy (CRT).
  
  
  RESULTS
  Sixty eight patients consecutive (LV ejection fraction 23 +/- 8%) with at least moderate MR (>or=grade 2+) were included. Echocardiography was performed at baseline, 1 day after CRT initiation and at 6 months follow-up. Speckle tracking radial strain was used to assess LV dyssynchrony at baseline. The majority of patients improved in MR after CRT, with 43% improving immediately after CRT, and 20% improving late (after 6 months) after CRT. Early and late responders had similar extent of LV dyssynchrony (209 +/- 115 ms vs. 190 +/- 118 ms, P = NS); however, the site of latest activation in early responders was mostly inferior or posterior (adjacent to the posterior papillary muscle), whereas the lateral wall was the latest activated segment in late responders.
  
  
  CONCLUSIONS
  Current data suggest that the presence of baseline LV dyssynchrony is related to improvement in MR after CRT. LV dyssynchrony involving the posterior papillary muscle may lead to an immediate reduction in MR, whereas LV dyssynchrony in the lateral wall resulted in late response to CRT.
authors.affiliation: Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
authors.forename: Claudia
authors.initials: C
authors.lastname: Ypenburg
authors.forename: Patrizio
authors.initials: P
authors.lastname: Lancellotti
authors.forename: Laurens F
authors.initials: LF
authors.lastname: Tops
authors.forename: Eric
authors.initials: E
authors.lastname: Boersma
authors.forename: Gabe B
authors.initials: GB
authors.lastname: Bleeker
authors.forename: Eduard R
authors.initials: ER
authors.lastname: Holman
authors.forename: James D
authors.initials: JD
authors.lastname: Thomas
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Schalij
authors.forename: Luc A
authors.initials: LA
authors.lastname: Piérard
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: Bax
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004452:Echocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008944:Mitral Valve Insufficiency / Q000503:physiopathology / Q000628:therapy*; D010138:Pacemaker, Artificial; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology / Q000628:therapy; D020257:Ventricular Remodeling