title: The anatomic and electrical location of the left ventricular lead predicts ventricular arrhythmia in cardiac resynchronization therapy.
abstract: BACKGROUND
  Both anatomic and electrical locations of the left ventricular (LV) lead have been identified as important predictors of clinical outcomes in cardiac resynchronization therapy (CRT). The impact of LV lead location on incident device-treated ventricular arrhythmia (VA), however, is not well understood.
  
  
  OBJECTIVE
  To assess the relationship between electrical and anatomic LV lead location and device treated VAs in CRT.
  
  
  METHODS
  Sixty-nine patients undergoing CRT implantation for standard indications were evaluated. Anatomic LV lead location was assessed by means of coronary venography and chest radiography and categorized as apical or nonapical. Electrical LV lead location was assessed by LV electrical delay (LVLED) and was calculated as the time between the onset of the native QRS on the surface electrocardiogram and sensed signal on the LV lead during implantation and corrected for native QRS. Incident appropriate device-treated VA was assessed via device interrogation.
  
  
  RESULTS
  Apical lead placement was an independent predictor of VAs (hazard ratio 5.29; 95% confidence interval 1.69-16.5; P = .004). Among patients with a nonapical lead, LVLED<50% native QRS was an independent predictor of VAs (hazard ratio 6.90; 95% confidence interval 1.53-31.1; P = .012). Those with a nonapical lead and LVLED ≥ 50% native QRS were at substantially lower risk for first incident and recurrent VAs when compared to all other patients.
  
  
  CONCLUSIONS
  The apical lead position is associated with an increased risk of VAs in CRT patients. Among patients with a nonapical lead position, an LVLED of<50% of the native QRS is associated with an increased risk of VAs.
authors.affiliation: Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Friedman
authors.forename: Gaurav A
authors.initials: GA
authors.lastname: Upadhyay
authors.forename: Robert K
authors.initials: RK
authors.lastname: Altman
authors.forename: Mary
authors.initials: M
authors.lastname: Orencole
authors.forename: Conor D
authors.initials: CD
authors.lastname: Barrett
authors.forename: Theofanie
authors.initials: T
authors.lastname: Mela
authors.forename: E
authors.initials: E
authors.lastname: Kevin Heist
authors.forename: Jagmeet P
authors.initials: JP
authors.lastname: Singh
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000503:physiopathology*; D058406:Cardiac Resynchronization Therapy / Q000009:adverse effects*; D004562:Electrocardiography; D004567:Electrodes, Implanted; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D016019:Survival Analysis; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000209:etiology / Q000503:physiopathology*