title: Effects of cardiac resynchronization therapy on left ventricular mass and wall thickness in mild heart failure patients in MADIT-CRT.
abstract: BACKGROUND
  The effect of cardiac resynchronization therapy (CRT) on left ventricular wall thickness and left ventricular mass (LVM) is unknown.
  
  
  OBJECTIVE
  To evaluate the effects of CRT on septal and posterior wall thickness (SWT and PWT) and LVM in patients with left bundle branch block (LBBB) and non-LBBB vs implantable cardioverter-defibrillator patients and to assess the relationship between CRT-induced changes and cardiac events.
  
  
  METHODS
  We investigated 843 patients with LBBB and 366 patients with non-LBBB enrolled in the Multicenter Automatic Defibrillator Implantation Trial - Cardiac Resynchronization Therapy (MADIT-CRT) trial to analyze changes in SWT, PWT, and LVM at 12 months and subsequent outcome. The primary end point was heart failure or death; secondary end points included ventricular tachycardia, ventricular fibrillation, or death.
  
  
  RESULTS
  In LBBB patients, reduction in SWT, PWT, and LVM was more pronounced in CRT defibrillator (CRT-D) than in implantable cardioverter-defibrillator (SWT:-6.7% ± 4.4% vs-1.0% ± 1.9%; PWT:-6.4% ± 4.3% vs-0.8% ± 1.9%; LVM:-23.6% ± 9.9% vs-5.1% ± 5.1%; P<.001 for all). In CRT-D patients with non-LBBB, LVM reduction was less pronounced; however, changes in SWT and PWT were comparable. Changes in LVM correlated with changes in left ventricular end-diastolic volume. In CRT-D patients with LBBB, reduction in SWT and LVM was associated with reduction in heart failure/death (SWT: hazard ratio 0.94; 95% confidence interval 0.89-0.99 per percent change; P = .03) and ventricular tachycardia/ventricular fibrillation/death (SWT: hazard ratio 0.95; 95% confidence interval 0.91-1.00; P = .04). CRT-D patients with non-LBBB did not show favorable reduction in clinical or arrhythmic end points related to changes in SWT, PWT, or LVM.
  
  
  CONCLUSIONS
  CRT-D was associated with significant reduction in SWT, PWT, and LVM in patients with LBBB along with left ventricular volume changes and associated favorable clinical and arrhythmia outcomes.
authors.affiliation: University of Rochester Medical Center, Rochester, New York 14642, USA. Valentina.Kutyifa@heart.rochester.edu
authors.forename: Valentina
authors.initials: V
authors.lastname: Kutyifa
authors.forename: Scott D
authors.initials: SD
authors.lastname: Solomon
authors.forename: Mikhail
authors.initials: M
authors.lastname: Bourgoun
authors.forename: Amil M
authors.initials: AM
authors.lastname: Shah
authors.forename: Anne-Catherine
authors.initials: AC
authors.lastname: Pouleur
authors.forename: Dorit
authors.initials: D
authors.lastname: Knappe
authors.forename: Scott
authors.initials: S
authors.lastname: McNitt
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Wang
authors.forename: Bela
authors.initials: B
authors.lastname: Merkely
authors.forename: Marc
authors.initials: M
authors.lastname: Pfeffer
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Moss
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
mesh_terms: D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D002306:Cardiac Volume; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D006346:Heart Septum / Q000000981:diagnostic imaging; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D013318:Stroke Volume; D016896:Treatment Outcome; D014463:Ultrasonography