title: Mode switching in dual chamber pacemakers: effect of onset criteria on arrhythmia-related symptoms.
abstract: OBJECTIVE
  Various mode-switching algorithms are available with different tachyarrhythmia detection criteria to be satisfied to initiate mode-switching. This study evaluated three different mode-switching algorithms in patients with paroxysmal atrial fibrillation.
  
  
  RESULTS
  Seventeen patients completed the study. Three mode-switching algorithms were downloaded as software into the pacemaker, each for 1 month in a single-blind, randomized sequence. The criteria to initiate mode-switching were: mean atrial rate ('standard'), '4-of-7' or '1-of-1' atrial intervals to exceed the atrial detection rate. Symptoms for each were measured using the Symptom Checklist Frequency and Severity index. The median number of mode-switch episodes increased from 20 for 'standard' to 39 for '4-of-7' (P=0.029 vs 'standard') and 103 for '1-of-1' (P=0.0012 vs 'standard') onset criteria. Median duration of episodes decreased from 2.5 min with 'standard' to 1.4 min with '4-of-7' and 0.4 min with '1-of-1' onset criteria. Frequency of symptoms was lower using '4-of-7' (18.2 +/- 12.0 vs 23 +/- 12.0, P=0.08) or '1-of-1' (20.4 +/- 12.4 vs 23 +/- 12.0, P=0.07) than 'standard' onset criteria. Severity of arrhythmia tended to be less with either '4-of-7' (16 +/- 10.4 vs 19.1 +/- 19.4, P=0.12) or '1-of-1' (17.5 +/- 10.3 vs 19.1 +/- 9.4, P=0.18) than with 'standard' onset criteria.
  
  
  CONCLUSIONS
  The more sensitive onset criteria for detection of atrial tachyarrhythmias were associated with lower frequency and severity of symptoms.
authors.affiliation: University of Brimingham, UK.
authors.forename: H J
authors.initials: HJ
authors.lastname: Marshall
authors.forename: G N
authors.initials: GN
authors.lastname: Kay
authors.forename: M
authors.initials: M
authors.lastname: Hess
authors.forename: V J
authors.initials: VJ
authors.lastname: Plumb
authors.forename: R S
authors.initials: RS
authors.lastname: Bubien
authors.forename: J
authors.initials: J
authors.lastname: Hummel
authors.forename: D
authors.initials: D
authors.lastname: Dawson
authors.forename: T
authors.initials: T
authors.lastname: Markewitz
authors.forename: M D
authors.initials: MD
authors.lastname: Gammage
mesh_terms: D000465:Algorithms; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D016037:Single-Blind Method