title: Occurrence of phrenic nerve stimulation in cardiac resynchronization therapy patients: the role of left ventricular lead type and placement site.
abstract: OBJECTIVE
  Unwanted phrenic nerve stimulation (PNS) has been reported in ∼1 in 4 patients undergoing left ventricular (LV) pacing. The occurrence of PNS over mid-term follow-up and the significance of PNS are less certain.
  
  
  RESULTS
  Data from 1307 patients enrolled in pre-market studies of LV leads manufactured by Medtronic (models 4193 and 4195 unipolar, 4194, 4196, 4296, and 4396 bipolar) were pooled. Left ventricular lead location was recorded at implant using a common classification scheme. Phrenic nerve stimulation symptoms were either spontaneously reported or identified at scheduled follow-up visits. A PNS-related complication was defined as PNS resulting in invasive intervention or the termination of LV pacing. Average follow-up was 14.9 months (range 0.0-46.6). Phrenic nerve stimulation symptoms occurred in 169 patients (12.9%). Phrenic nerve stimulation-related complications occurred in 21 of 1307 patients (1.6%); 16 of 738 (2.2%) in the unipolar lead studies, and 5 of 569 (0.9%) in the bipolar lead studies (P = 0.08). Phrenic nerve stimulation was more frequent at middle-lateral/posterior, and apical LV sites (139/1010) vs. basal-posterior/lateral/anterior, and middle-anterior sites (20/297; P= 0.01). As compared with an anterior LV lead position, a lateral LV pacing site was associated with over a four-fold higher risk of PNS (P= 0.005) and an apical LV pacing site was associated with over six-fold higher risk of PNS (P= 0.001).
  
  
  CONCLUSIONS
  Phrenic nerve stimulation occurred in 13% of patients undergoing LV lead placement and was more common at mid-lateral/posterior, and LV apical sites. Most cases (123/139; 88%) of PNS were mitigated via electrical reprogramming, without the need for invasive intervention.
authors: Institute of Cardiology, University of Bologna, Via Massarenti 9, 40138 Bologna, Italy. mauro.biffi@aosp.bo.it
authors: Mauro
authors: M
authors: Biffi
authors: Derek V
authors: DV
authors: Exner
authors: George H
authors: GH
authors: Crossley
authors: Brian
authors: B
authors: Ramza
authors: Benoit
authors: B
authors: Coutu
authors: Gery
authors: G
authors: Tomassoni
authors: Wolfgang
authors: W
authors: Kranig
authors: Shelby
authors: S
authors: Li
authors: Nina
authors: N
authors: Kristiansen
authors: Frederik
authors: F
authors: Voss
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy / Q000706:statistics & numerical data*; D015897:Comorbidity; D004567:Electrodes, Implanted / Q000706:statistics & numerical data*; D004868:Equipment Failure / Q000706:statistics & numerical data; D005260:Female; D006333:Heart Failure / Q000453:epidemiology* / Q000517:prevention & control*; D006352:Heart Ventricles / Q000601:surgery; D006801:Humans; D015994:Incidence; D038622:Internationality; D008297:Male; D010523:Peripheral Nervous System Diseases / Q000453:epidemiology*; D010791:Phrenic Nerve; D019919:Prosthesis Implantation / Q000379:methods* / Q000706:statistics & numerical data; D012189:Retrospective Studies