title: Utility of a novel pacing guidewire in pre-implantation testing at different left ventricular sites in cardiac resynchronization therapy procedures.
abstract: OBJECTIVE
  This study aimed to evaluate the utility of a novel pacing guidewire in pre-implantation testing of different left ventricular (LV) sites during cardiac resynchronization therapy (CRT) procedures.
  
  
  METHODS
  Ten consecutive patients (8 male, mean age 65.8 ± 4.9) undergoing CRT procedures were studied. Pacing threshold and R-wave sensing measured by the guidewire and LV lead at different LV sites were compared.
  
  
  RESULTS
  Thirty sites (6 apical, 13 middle, and 11 basal; 15 lateral and 15 anterior) were tested. There was significant correlation between pacing threshold (r = 0.878, p < 0.0001), and R-wave sensing (r = 0.896, p < 0.0001) obtained by guidewire and those obtained by LV lead. Separating into lateral and anterior sites, significant correlation was also found in pacing threshold (lateral r = 0.658, p = 0.008; anterior r = 0.886, p < 0.0001) and R-wave sensing (lateral r = 0.887, p < 0.0001; anterior 0.865, p < 0.0001). For basal and middle sites, significant correlation was found in pacing threshold (basal r = 0.890, p < 0.0001; middle r = 0.878, p < 0.0001), and R-wave sensing (basal r = 0.930, p < 0.0001; middle r = 0.823, p < 0.001). No and borderline correlation was found in pacing threshold (r = 0.548, p = 0.26) and R-wave sensing (r = 0.835, p = 0.039), respectively, for apical sites. Concordance rate for the presence of phrenic nerve stimulation at high pacing output was 87%.
  
  
  CONCLUSIONS
  The accuracy of the novel pacing guidewire in pre-implantation testing in CRT procedures is site-dependent. There was good correlation with LV lead in the measurement of pacing threshold and R-wave sensing at basal and middle sites, but not apical sites. Presence of phrenic nerve stimulation can be predicted by guidewire testing with high accuracy.
authors.affiliation: Princess Margaret Hospital, Lai Chi Kok, Hong Kong. ngaiyinchan@yahoo.com.hk
authors.forename: Ngai Yin
authors.initials: NY
authors.lastname: Chan
authors.forename: Chi Chung
authors.initials: CC
authors.lastname: Choy
authors.forename: Chun Leung
authors.initials: CL
authors.lastname: Lau
authors.forename: Ying Keung
authors.initials: YK
authors.lastname: Lo
authors.forename: Pui Shan
authors.initials: PS
authors.lastname: Chu
authors.forename: Ho Chuen
authors.initials: HC
authors.lastname: Yuen
authors.forename: Suet Ting
authors.initials: ST
authors.lastname: Lau
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy / Q000379:methods; D004567:Electrodes, Implanted; D005260:Female; D006333:Heart Failure / Q000628:therapy; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D019919:Prosthesis Implantation / Q000295:instrumentation*