title: Apical versus Non-Apical Lead: Is ICD Lead Position Important for Successful Defibrillation?
abstract: We aim to compare the acute and long-term success of defibrillation between non-apical and apical ICD lead position.
  
  
  
  The position of the ventricular lead was recorded by the implanting physician for 2,475 of 2,500 subjects in the Shockless IMPLant Evaluation (SIMPLE) trial, and subjects were grouped accordingly as non-apical or apical. The success of intra-operative defibrillation testing and of subsequent clinical shocks were compared. Propensity scoring was used to adjust for the impact of differences in baseline variables between these groups. There were 541 leads that were implanted at a non-apical position (21.9%). Patients implanted with a non-apical lead had a higher rate of secondary prevention indication. Non-apical location resulted in a lower mean R-wave amplitude (14.0 vs. 15.2, P < 0.001), lower mean pacing impedance (662 ohm vs. 728 ohm, P < 0.001), and higher mean pacing threshold (0.70 V vs. 0.66 V, P = 0.01). Single-coil leads and cardiac resynchronization devices were used more often in non-apical implants. The success of intra-operative defibrillation was similar between propensity score matched groups (89%). Over a mean follow-up of 3 years, there were no significant differences in the yearly rates of appropriate shock (5.5% vs. 5.4%, P = 0.98), failed appropriate first shock (0.9% vs. 1.0%, P = 0.66), or the composite of failed shock or arrhythmic death (2.8% vs. 2.3% P = 0.35) according to lead location.
  
  
  
  We did not detect any reduction in the ICD efficacy at the time of implant or during follow-up in patients receiving a non-apical RV lead.
authors.affiliation: Hamilton Health Sciences, Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Guy
authors.initials: G
authors.lastname: Amit
authors.affiliation: Hamilton Health Sciences, Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.affiliation: Hamilton Health Sciences, Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Connolly
authors.affiliation: Leviev Heart Center, Sheba Medical Center, Tel Hashomer, Israel.
authors.forename: Michael
authors.initials: M
authors.lastname: Glikson
authors.affiliation: J.W. Goethe University, Frankfurt, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Hohnloser
authors.affiliation: Liverpool Heart and Chest Hospital, Liverpool, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Wright
authors.affiliation: Klinikum Coburg GbmH, Coburg, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Brachmann
authors.affiliation: CHU Hopital Michallon, Grenoble, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Defaye
authors.affiliation: Klinikum Kassel, Kassel, Germany.
authors.forename: Joerg
authors.initials: J
authors.lastname: Neuzner
authors.affiliation: Centre Hospitalier Universitaire, Rennes, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Mabo
authors.affiliation: Leiden University Medical Center, Leiden, the Netherlands.
authors.forename: Liselot
authors.initials: L
authors.lastname: Vanerven
authors.affiliation: Hospital de Santa Creu i Sant Pau, Barcelona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Vinolas
authors.affiliation: Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada.
authors.forename: Gilles
authors.initials: G
authors.lastname: O'Hara
authors.affiliation: Institute for Clinical and Experimental Medicine, Prague, Czech Republic.
authors.forename: Josef
authors.initials: J
authors.lastname: Kautzner
authors.affiliation: Boston Scientific, Minneapolis, Minnesota, USA.|Boston Scientific, Brussels, Belgium.
authors.forename: Ursula
authors.initials: U
authors.lastname: Appl
authors.affiliation: Karolinska Institute, Stockholm, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Gadler
authors.affiliation: Boston Scientific, Minneapolis, Minnesota, USA.|Boston Scientific, Brussels, Belgium.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Stein
authors.affiliation: Soroka Medical Center, Ben-Gurion University, Beer-Sheva, Israel.
authors.forename: Yuval
authors.initials: Y
authors.lastname: Konstantino
authors.affiliation: Hamilton Health Sciences, Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Jeff S
authors.initials: JS
authors.lastname: Healey
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000150:complications / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D002304:Cardiac Pacing, Artificial; D016757:Death, Sudden, Cardiac / Q000209:etiology; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods / Q000401:mortality; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D057216:Propensity Score; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
keywords: cardiac resynchronization therapy; defibrillation safety margin; defibrillation testing; failed shocks; implantable cardioverter defibrillator; inappropriate shocks; right ventricular lead