title: Age, prognostic impact of QRS prolongation and left bundle branch block, and utilization of cardiac resynchronization therapy: findings from 14,713 patients in the Swedish Heart Failure Registry.
abstract: OBJECTIVE
  Age is not a contraindication to cardiac resynchronization therapy (CRT), but the prevalence and prognostic impact of QRS prolongation with intraventricular conduction delay (IVCD) and left bundle branch block (LBBB), as well as CRT utilization, may differ with age. We tested the hypotheses that in the elderly: (i) IVCD and LBBB are more prevalent, (ii) IVCD and LBBB are more harmful, and (iii) CRT is underutilized.
  
  
  RESULTS
  We studied 14 713 patients with ejection fraction ≤39% in the Swedish Heart Failure Registry and divided into age groups ≤65 years, 66-80 years and >80 years. Among 13 782 patients without CRT, IVCD was present in the three age groups in 11% vs. 15% vs. 19% and LBBB was present in 20% vs. 27% vs. 28%, respectively, (P < 0.001). The multivariable hazard ratio (HR) for all-cause mortality over a median (interquartile range) follow-up of 29 (12-53) months for IVCD vs. narrow QRS was 1.31 (1.06-1.63, P = 0.013) in the ≤65 year group, 1.32 (1.17-1.47, P < 0.001) in the 66-80 year group, and 1.26 (1.21-1.41, p < 0.001) in the >80 year group. For LBBB vs. narrow QRS it was 1.29 (1.07-1.56, P = 0.009), 1.17 (1.06-1.30, P = 0.002), and 1.10 (0.99-1.22, P = 0.091), respectively. The adjusted P for interaction between age and QRS morphology was 0.664. In the three age groups, CRT was present in 6% vs. 8% vs. 4% and absent but with indication in 23% vs. 32% vs. 37%, respectively (P < 0.001).
  
  
  CONCLUSIONS
  Both IVCD and LBBB were more common with increasing age and were similarly strong independent predictors of mortality and in all ages. The underutilization of CRT was worse with increasing age.
authors.affiliation: Karolinska Institutet, Department of Medicine, Stockholm, Sweden; Karolinska University Hospital, Department of Medicine, Unit of Cardiology, N305, 17176, Stockholm, Sweden.
authors.forename: Lars H
authors.initials: LH
authors.lastname: Lund
authors.forename: Lina
authors.initials: L
authors.lastname: Benson
authors.forename: Marcus
authors.initials: M
authors.lastname: Ståhlberg
authors.forename: Frieder
authors.initials: F
authors.lastname: Braunschweig
authors.forename: Magnus
authors.initials: M
authors.lastname: Edner
authors.forename: Ulf
authors.initials: U
authors.lastname: Dahlström
authors.forename: Cecilia
authors.initials: C
authors.lastname: Linde
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D053840:Brugada Syndrome; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D000075224:Cardiac Conduction System Disease; D058406:Cardiac Resynchronization Therapy / Q000706:statistics & numerical data*; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006329:Heart Conduction System / Q000002:abnormalities*; D006333:Heart Failure / Q000150:complications / Q000175:diagnosis / Q000401:mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011379:Prognosis; D012042:Registries; D013548:Sweden / Q000453:epidemiology; D016896:Treatment Outcome
keywords: Age; Cardiac resynchronization therapy; Epidemiology; Heart Failure; Intraventricular conduction delay; Left bundle branch block; QRS width