title: Survival with cardiac-resynchronization therapy in mild heart failure.
abstract: BACKGROUND
  The Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT) showed that early intervention with cardiac-resynchronization therapy with a defibrillator (CRT-D) in patients with an electrocardiographic pattern showing left bundle-branch block was associated with a significant reduction in heart-failure events over a median follow-up of 2.4 years, as compared with defibrillator therapy alone.
  
  
  METHODS
  We evaluated the effect of CRT-D on long-term survival in the MADIT-CRT population. Post-trial follow-up over a median period of 5.6 years was assessed among all 1691 surviving patients (phase 1) and subsequently among 854 patients who were enrolled in post-trial registries (phase 2). All reported analyses were performed on an intention-to-treat basis.
  
  
  RESULTS
  At 7 years of follow-up after initial enrollment, the cumulative rate of death from any cause among patients with left bundle-branch block was 18% among patients randomly assigned to CRT-D, as compared with 29% among those randomly assigned to defibrillator therapy alone (adjusted hazard ratio in the CRT-D group, 0.59; 95% confidence interval [CI], 0.43 to 0.80; P<0.001). The long-term survival benefit of CRT-D in patients with left bundle-branch block did not differ significantly according to sex, cause of cardiomyopathy, or QRS duration. In contrast, CRT-D was not associated with any clinical benefit and possibly with harm in patients without left bundle-branch block (adjusted hazard ratio for death from any cause, 1.57; 95% CI, 1.03 to 2.39; P=0.04; P<0.001 for interaction of treatment with QRS morphologic findings).
  
  
  CONCLUSIONS
  Our findings indicate that in patients with mild heart-failure symptoms, left ventricular dysfunction, and left bundle-branch block, early intervention with CRT-D was associated with a significant long-term survival benefit. (Funded by Boston Scientific; ClinicalTrials.gov numbers, NCT00180271, NCT01294449, and NCT02060110.).
authors.affiliation: The authors' affiliations are listed in the Appendix.
authors.forename: Ilan
authors.initials: I
authors.lastname: Goldenberg
authors.forename: Valentina
authors.initials: V
authors.lastname: Kutyifa
authors.forename: Helmut U
authors.initials: HU
authors.lastname: Klein
authors.forename: David S
authors.initials: DS
authors.lastname: Cannom
authors.forename: Mary W
authors.initials: MW
authors.lastname: Brown
authors.forename: Ariela
authors.initials: A
authors.lastname: Dan
authors.forename: James P
authors.initials: JP
authors.lastname: Daubert
authors.forename: N A Mark
authors.initials: NA
authors.lastname: Estes
authors.forename: Elyse
authors.initials: E
authors.lastname: Foster
authors.forename: Henry
authors.initials: H
authors.lastname: Greenberg
authors.forename: Josef
authors.initials: J
authors.lastname: Kautzner
authors.forename: Robert
authors.initials: R
authors.lastname: Klempfner
authors.forename: Malte
authors.initials: M
authors.lastname: Kuniss
authors.forename: Bela
authors.initials: B
authors.lastname: Merkely
authors.forename: Marc A
authors.initials: MA
authors.lastname: Pfeffer
authors.forename: Aurelio
authors.initials: A
authors.lastname: Quesada
authors.forename: Sami
authors.initials: S
authors.lastname: Viskin
authors.forename: Scott
authors.initials: S
authors.lastname: McNitt
authors.forename: Bronislava
authors.initials: B
authors.lastname: Polonsky
authors.forename: Ali
authors.initials: A
authors.lastname: Ghanem
authors.forename: Scott D
authors.initials: SD
authors.lastname: Solomon
authors.forename: David
authors.initials: D
authors.lastname: Wilber
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Moss
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000150:complications / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy; D003131:Combined Modality Therapy; D017147:Defibrillators, Implantable; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications / Q000401:mortality / Q000517:prevention & control / Q000628:therapy*; D006801:Humans; D057194:Intention to Treat Analysis; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012720:Severity of Illness Index; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000150:complications