title: Prominent R wave in ECG lead V1 predicts improvement of left ventricular ejection fraction after cardiac resynchronization therapy in patients with or without left bundle branch block.
abstract: BACKGROUND
  QRS morphology on postprocedural ECG indicating posterolateral left ventricular pacing may be predictive of response to cardiac resynchronization therapy (CRT).
  
  
  OBJECTIVE
  The purpose of this study was to assess whether a positive vector in V1 and/or negative vector in lead I on the first postprocedural ECG, suggesting posterolateral capture from CRT, correlates with improvement in left ventricular ejection fraction (LVEF).
  
  
  METHODS
  A retrospective chart review was conducted on all patients who underwent CRT implantation at our institution between April 2008 and December 2011. Biventricular (BiV) paced QRS morphology was defined as R/S ≥1 in V1 and/or R/S ≤ 1 in lead I. The primary outcome was improvement of LVEF ≥7.5%. The χ(2) and t tests were used for analysis.
  
  
  RESULTS
  Of 68 patients, 49 (72%) met our BiV paced QRS morphology criteria. Thirty-four of these 49 patients (69%) had improvement in LVEF. Of the 19 patients who did not meet our criteria, 17 (89%) did not have an improvement in LVEF (sensitivity 94%, specificity 53%, χ(2) = 19.04, P < .0001). The average LVEF improvement in patients who met our BiV paced QRS morphology criteria was significantly greater than in those who did not (14.27% vs 2.63%, P = .0001). Preprocedural left bundle branch block was not a predictor of echocardiographic response.
  
  
  CONCLUSIONS
  Our results highlight the importance of periprocedural ECG analysis to optimize response to CRT. Moreover, patients without left bundle branch block still benefited from CRT if they met our BiV paced morphology criteria. This suggests that postprocedural left ventricular activation as reflected on the ECG may supersede the baseline conduction delay.
authors.affiliation: Division of Cardiology, University of North Carolina Hospitals, Chapel Hill, North Carolina.
authors.forename: Weeranun D
authors.initials: WD
authors.lastname: Bode
authors.affiliation: Division of Cardiology, University of North Carolina Hospitals, Chapel Hill, North Carolina.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Bode
authors.affiliation: Division of Cardiology, University of North Carolina Hospitals, Chapel Hill, North Carolina.
authors.forename: Leonard
authors.initials: L
authors.lastname: Gettes
authors.affiliation: Division of Cardiology, University of North Carolina Hospitals, Chapel Hill, North Carolina.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Jensen
authors.affiliation: Division of Cardiology, University of North Carolina Hospitals, Chapel Hill, North Carolina.
authors.forename: John P
authors.initials: JP
authors.lastname: Mounsey
authors.affiliation: Division of Cardiology, University of North Carolina Hospitals, Chapel Hill, North Carolina. Electronic address: ehchung@med.unc.edu.
authors.forename: Eugene H
authors.initials: EH
authors.lastname: Chung
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013318:Stroke Volume / Q000502:physiology*; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: Biventricular pacing; Cardiac resynchronization therapy; Electrocardiographic criteria; Left bundle branch block; Left ventricular ejection fraction; QRS morphology