title: Reduction of RV pacing by continuous optimization of the AV interval.
abstract: BACKGROUND
  In patients requiring permanent pacing, preservation of intrinsic ventricular activation is preferred whenever possible. The Search AV+ (SAV+) algorithm in Medtronic EnPulsetrade mark dual-chamber pacemakers can increase atrioventricular (AV) intervals to 320 ms in patients with intact or intermittent AV conduction. This prospective, multicenter study compared the percentage of ventricular pacing with and without AV interval extension.
  
  
  METHODS
  Among 197 patients enrolled in the study, the percentage of ventricular-paced beats was evaluated via device diagnostics at the 1-month follow-up. Patient cohorts were defined by clinician assessment of conduction via a 1:1 AV conduction test at the 2-week follow-up. The observed percentage of ventricular pacing with SAV + ON and the predicted percentage of ventricular pacing with SAV + OFF were determined from the SAV + histogram data for the period between the 2-week and 1-month follow-up visits.
  
  
  RESULTS
  Of 197 patients, 110 (55.8%) had intact 1:1 AV conduction, of which 109 had 1-month data. SAV + remained ON in 99/109 patients; 10 patients had intrinsic A-V conduction intervals beyond SAV + nominal and therefore SAV + disabled. The mean percentage of ventricular pacing in the 109 patients was SAV+ ON = 23.1% (median 3.7%) versus SAV + OFF = 97.2% (median 99.7%). In 87 patients without 1:1 AV conduction, SAV + was programmed OFF in 6, automatically disabled in 52, and remained ON in 29. In 8 of these patients, 80-100% reduction in ventricular pacing was observed with SAV + ON.
  
  
  CONCLUSIONS
  The Search AV+ algorithm in the EnPulse pacemaker effectively promotes intrinsic ventricular activation and substantially reduces unnecessary ventricular pacing.
authors.affiliation: Pacemaker Center, Clinical Center of Serbia, Belgrade, Serbia and Montenegro. goran_milas@yahoo.com
authors.forename: Goran
authors.initials: G
authors.lastname: Milasinovic
authors.forename: Johannes
authors.initials: J
authors.lastname: Sperzel
authors.forename: Timothy W
authors.initials: TW
authors.lastname: Smith
authors.forename: Hardwin
authors.initials: H
authors.lastname: Mead
authors.forename: Johan
authors.initials: J
authors.lastname: Brandt
authors.forename: Wesley K
authors.initials: WK
authors.lastname: Haisty
authors.forename: J Russell
authors.initials: JR
authors.lastname: Bailey
authors.forename: Marc
authors.initials: M
authors.lastname: Roelke
authors.forename: Jay
authors.initials: J
authors.lastname: Simonson
authors.forename: Bart
authors.initials: B
authors.lastname: Gerritse
authors.forename: Jennifer
authors.initials: J
authors.lastname: Englund
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Compton
mesh_terms: D000368:Aged; D000465:Algorithms; D002304:Cardiac Pacing, Artificial / Q000379:methods* / Q000706:statistics & numerical data; D015331:Cohort Studies; D015897:Comorbidity; D019544:Equipment Failure Analysis; D005060:Europe / Q000453:epidemiology; D005260:Female; D006333:Heart Failure / Q000453:epidemiology / Q000517:prevention & control; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial / Q000706:statistics & numerical data*; D011379:Prognosis; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D013813:Therapy, Computer-Assisted / Q000379:methods* / Q000706:statistics & numerical data; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D014693:Ventricular Fibrillation / Q000453:epidemiology* / Q000517:prevention & control*