title: High incidence of pacemaker syndrome in patients with sinus node dysfunction treated with ventricular-based pacing in the Mode Selection Trial (MOST).
abstract: OBJECTIVE
  We evaluated the incidence, predictors, and treatment of pacemaker syndrome in patients with sinus node dysfunction treated with ventricular-based (VVIR) pacing in the Mode Selection Trial (MOST).
  
  
  BACKGROUND
  Pacemaker syndrome, or intolerance to VVIR pacing, consists of cardiovascular signs and symptoms induced by VVIR pacing.
  
  
  METHODS
  The definition of pacemaker syndrome required that a patient with single-chamber VVIR pacing develop either congestive signs and symptoms associated with retrograde conduction during VVIR pacing or a >or=20 mm Hg reduction of systolic blood pressure during VVIR pacing, associated with reproducible symptoms of weakness, lightheadedness, or syncope.
  
  
  RESULTS
  Of 996 patients randomized to VVIR pacing, 182 (18.3%) met criteria for pacemaker syndrome in follow-up. Pacemaker syndrome occurred early in most patients (13.8% at 6 months, 16.0% at 1 year, increasing to 19.7% at 4 years). Baseline univariate predictors of pacemaker syndrome included a lower sinus rate and higher programmed pacemaker rate. Previous heart failure, ejection fraction, and drop in systolic blood pressure with VVIR pacing at implantation did not predict the development of pacemaker syndrome. Post-implantation predictors of pacemaker syndrome were a higher percentage of paced beats, higher programmed low rate, and slower underlying spontaneous sinus rate. Quality of life decreased at the time of diagnosis of pacemaker syndrome and improved with reprogramming to atrial-based pacing.
  
  
  CONCLUSIONS
  Severe pacemaker syndrome developed in nearly 20% of VVIR-paced patients and improved with reprogramming to the dual-chamber pacing mode. Because prediction of pacemaker syndrome is difficult, the only way to prevent pacemaker syndrome is to implant atrial-based pacemakers in all patients.
authors.affiliation: Tufts-New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02111, USA. MLink@tufts-nemc.org
authors.forename: Mark S
authors.initials: MS
authors.lastname: Link
authors.forename: Anne S
authors.initials: AS
authors.lastname: Hellkamp
authors.forename: N A Mark
authors.initials: NA
authors.lastname: Estes
authors.forename: E John
authors.initials: EJ
authors.lastname: Orav
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Ellenbogen
authors.forename: Bassiema
authors.initials: B
authors.lastname: Ibrahim
authors.forename: Arnold
authors.initials: A
authors.lastname: Greenspon
authors.forename: Carlos
authors.initials: C
authors.lastname: Rizo-Patron
authors.forename: Lee
authors.initials: L
authors.lastname: Goldman
authors.forename: Kerry L
authors.initials: KL
authors.lastname: Lee
authors.forename: Gervasio A
authors.initials: GA
authors.lastname: Lamas
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D016032:Randomized Controlled Trials as Topic; D012804:Sick Sinus Syndrome / Q000628:therapy*; D013575:Syncope / Q000209:etiology*; D013577:Syndrome; D016896:Treatment Outcome