title: Vector selection of a quadripolar left ventricular pacing lead affects acute hemodynamic response to cardiac resynchronization therapy: a randomized cross-over trial.
abstract: BACKGROUND
  A suboptimal left ventricular (LV) pacing site may account for non-responsiveness of patients to cardiac resynchronization therapy (CRT). The vector selection of a novel quadripolar LV pacing lead, which was mainly developed to overcome technical issues with stimulation thresholds and phrenic nerve capture, may affect hemodynamic response, and was therefore assessed in this study. (German Clinical Trials Register DRKS00000573).
  
  
  RESULTS
  Hemodynamic effects of a total of 145 LVPCs (9.1 per patient) of CRT devices with a quadripolar LV lead (Quartet™, St. Jude Medical) were assessed in 16/20 consecutive patients by invasive measurement of LV+dP/dtmax at an invasively optimized AV-interval in random order. Optimal (worst) LVPCs per patient were identified as those with maximal (minimal) %change in LV+dP/dtmax (%ΔLV+dP/dtmax) as compared to a preceding baseline. LV+dP/dtmax significantly increased in all 145 LVPCs (p<0.0001 compared to baseline) with significant intraindividual differences between LVPCs (p<0.0001). Overall, CRT acutely augmented %ΔLV+dP/dtmax by 31.3% (95% CI 24%-39%) in the optimal, by 21.3% (95% CI: 15%-27%) in the worst and by 28.2% (95% CI: 21%-36%) in a default distal LVPC. This resulted in an absolute additional acute increase in %ΔLV+dP/dtmax of 10.0% (95% CI: 7%-13%) of the optimal when compared to the worst (p<0.0001), and of 3.1% (95% CI: 1%-5%) of the optimal when compared to the default distal LVPC (p<0.001). Optimal LVPCs were not programmable with a standard bipolar lead in 44% (7/16) of patients.
  
  
  CONCLUSIONS
  The pacing configuration of a quadripolar LV lead determinates acute hemodynamic response. Pacing in the individually optimized configuration gives rise to an additional absolute 10% increase in %ΔLV+dP/dtmax when comparing optimal and worst vectors.
authors.affiliation: University Heart Center Freiburg, Germany. stefan.asbach@universitaets-herzzentrum.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Asbach
authors.forename: Maximilian
authors.initials: M
authors.lastname: Hartmann
authors.forename: Tobias
authors.initials: T
authors.lastname: Wengenmayer
authors.forename: Erika
authors.initials: E
authors.lastname: Graf
authors.forename: Christoph
authors.initials: C
authors.lastname: Bode
authors.forename: Juergen
authors.initials: J
authors.lastname: Biermann
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy; D058409:Cardiac Resynchronization Therapy Devices; D018592:Cross-Over Studies; D004567:Electrodes, Implanted; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male