title: Phrenic nerve stimulation in CRT patients and benefits of electronic lead repositioning: the ERACE trial.
abstract: OBJECTIVE
  Despite novel left ventricular (LV) lead technologies, phrenic nerve stimulation (PNS) remains an adverse effect observed in many patients with cardiac resynchronization therapy (CRT). Beyond anatomic repositioning, modern CRT devices allow avoidance of PNS also by software-based adaption of the pacing configuration. The Electronic Repositioning With Acuity and Easytrak Leads study evaluated the incidence of PNS in a CRT population and examined how often LV lead relocation can be avoided by "electronic repositioning" (ER).
  
  
  METHODS
  Patients who had an indication for implantation of a first CRT defibrillator with the option of ER were enrolled. Primary endpoint was the efficiency of ER determined by the frequency of PNS with the standard pacing configuration (LV tip to RV coil) avoidable by ER. PNS and pacing parameters were evaluated during implant, predischarge, and first routine follow-up (FU) using four different pacing configurations available by ER.
  
  
  RESULTS
  In total, 292 patients were enrolled and provided with a transvenous LV lead (82.2 % male, 65.5 ± 9.2 years old). The majority of the population was in NYHA III (84.2 %) with a LV ejection fraction of 25.3 ± 6.8 % and mean QRS width of 155 ± 27 ms, ischemic cardiomyopathy was present in 43.6 %. Median FU was 116 days. In the standard pacing configuration, PNS was inducible in 19.0/25.6/24.6 % at implant/predischarge/FU, respectively, resulting in 32.2 % of the patients presenting at least once with PNS. The safety margin for the standard pacing configuration between LV and PNS threshold was <1.0 V at 0.5 ms in 5.6/7.0/5.0 % of the patients, corresponding with a total rate of 11.6 % during the FU. In the finally chosen configuration, clinically relevant PNS occurred in 1.0/2.2/1.3 %. The four vector configurations allowed all but 6 of 292 (2 %) patients to be reprogrammed using ER without reoperation.
  
  
  CONCLUSIONS
  The incidence of inducible PNS in CRT patients is considerable. In this study, PNS could be avoided in the majority of the patients by means of electronic repositioning. Thus, the use of ER should be considered for CRT patients.
authors.affiliation: German Heart Institute, Berlin, Germany, stephan-goetze@web.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Goetze
authors.forename: Pascal
authors.initials: P
authors.lastname: Defaye
authors.forename: Alexander
authors.initials: A
authors.lastname: Bauer
authors.forename: Matthias
authors.initials: M
authors.lastname: Merkel
authors.forename: Olivier
authors.initials: O
authors.lastname: Bizeau
authors.forename: Sven
authors.initials: S
authors.lastname: Treusch
authors.forename: Klaus
authors.initials: K
authors.lastname: Contzen
authors.forename: Claus
authors.initials: C
authors.lastname: Juenger
authors.forename: Joachim
authors.initials: J
authors.lastname: Winter
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy / Q000706:statistics & numerical data*; D002637:Chest Pain / Q000453:epidemiology*; D015897:Comorbidity; D004567:Electrodes, Implanted / Q000706:statistics & numerical data*; D005260:Female; D005602:France / Q000453:epidemiology; D005858:Germany / Q000453:epidemiology; D006333:Heart Failure / Q000453:epidemiology* / Q000517:prevention & control*; D006801:Humans; D015994:Incidence; D008297:Male; D010523:Peripheral Nervous System Diseases / Q000453:epidemiology*; D010791:Phrenic Nerve; D019919:Prosthesis Implantation / Q000379:methods / Q000706:statistics & numerical data; D012120:Respiration Disorders / Q000453:epidemiology; D018570:Risk Assessment; D016896:Treatment Outcome