title: Native QRS narrowing reflects electrical reversal and associates with anatomical reversal in cardiac resynchronization therapy.
abstract: OBJECTIVE
  Abbreviation of paced QRS duration has been taken as electrical resynchronization imposed by cardiac resynchronization therapy (CRT). However, little is known about alteration in native QRS duration and its correlation with therapeutic response as well as anatomical remodeling post-CRT.
  
  
  METHODS
  Data of 74 consecutive patients with complete ECG records were reviewed. Response was defined as absolute improvement in LVEF by ≥10% from baseline. Changes in native QRS duration (native ΔQRS) were analyzed to CRT response and to changes in echocardiography.
  
  
  RESULTS
  Over median follow-up of 13 months, 47 patients had response to CRT and 30 subjects had abbreviation in native QRS duration. Native ΔQRS correlated positively with QRS duration pre- and post-CRT as well as with changes in echocardiography. Reversal of electrical remodeling as assessed by native QRS narrowing accompanied with greater improvements in LVEF (20% ± 11% vs 10% ± 10%, p = 0.000) and LVEDD (14 ± 11 mm vs. 4 ± 10 mm, p = 0.000). Multivariate analysis indicated that native ΔQRS was the lone independent factor of ECG in association to response to CRT (OR1.049, 95%CI 1.015-1.085, p = 0.004): 83.3% of patients with native QRS reduction were responders. Among the non-responders, 18.5% had native QRS narrowing at follow-ups.
  
  
  CONCLUSIONS
  Native QRS narrowing associated with beneficial response and greater improvements in echocardiography. Abbreviation in native QRS duration could reflect electrical reversal imposed by CRT.
authors.affiliation: Centre of Arrhythmia Diagnosis and Treatment, Fuwai Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 167 Beilishi Road, Xicheng District, 100037, Beijing, China.
authors.forename: Xin-wei
authors.initials: XW
authors.lastname: Yang
authors.forename: Wei
authors.initials: W
authors.lastname: Hua
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Zhi-min
authors.initials: ZM
authors.lastname: Liu
authors.forename: Li-gang
authors.initials: LG
authors.lastname: Ding
authors.forename: Ke-ping
authors.initials: KP
authors.lastname: Chen
authors.forename: Shu
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000628:therapy; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D058409:Cardiac Resynchronization Therapy Devices; D009202:Cardiomyopathies / Q000175:diagnosis / Q000628:therapy; D015331:Cohort Studies; D016001:Confidence Intervals; D015150:Echocardiography, Doppler / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology; D006331:Heart Diseases / Q000175:diagnosis* / Q000503:physiopathology*; D006333:Heart Failure / Q000175:diagnosis / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D018570:Risk Assessment; D016896:Treatment Outcome; D020257:Ventricular Remodeling / Q000502:physiology*