title: Heart failure hospitalization is more common in pacemaker patients with sinus node dysfunction and a prolonged paced QRS duration.
abstract: OBJECTIVE
  The purpose of this study was to determine whether a prolonged paced QRS duration increases the risk of cardiac dysfunction.
  
  
  BACKGROUND
  Right ventricular apical pacing mimics left bundle branch block, results in a prolonged QRS duration of variable duration, and causes ventricular desynchronization.
  
  
  METHODS
  In the Mode Selection Trial (MOST), QRS duration was measured in patients who had at least one paced ventricular complex recorded on 12-lead ECG within 3 months of enrollment (early) and after 9 months (late). Clinical endpoints including heart failure hospitalization, mortality, and atrial fibrillation were analyzed. A total of 1,026 patients were included in the analysis. Median age was 75 years (25th, 75th percentiles = 69, 80) and median ejection fraction prior to implant was 55% (45, 60). The cumulative percent ventricular pacing (DDDR and VVIR) was 81% over a median follow-up of 33 months. During period, 123 patients had heart failure hospitalization, 197 died, and 261 patients had atrial fibrillation.
  
  
  RESULTS
  Cox proportional hazards models demonstrated that paced QRS duration was a strong predictor of heart failure hospitalization (hazard ratio 1.15; 95% confidence interval 1.07,1.23) for each 10-ms increase in paced QRS duration (P = .001). The increased risk was unaffected by adjustment for other known predictors of heart failure hospitalization in the study. Paced QRS duration was not significant for mortality (P = .41) or atrial fibrillation (P = .20) when baseline QRS duration and other predictors were included.
  
  
  CONCLUSIONS
  Paced QRS duration is a significant, independent predictor of heart failure hospitalization in patients with sinus node dysfunction. A very long paced QRS duration is associated with increased heart failure hospitalization.
authors.affiliation: University of Missouri-Columbia, Columbia, Missouri, USA. hh.shukla@gmail.com
authors.forename: Himanshu H
authors.initials: HH
authors.lastname: Shukla
authors.forename: Anne S
authors.initials: AS
authors.lastname: Hellkamp
authors.forename: Erskine A
authors.initials: EA
authors.lastname: James
authors.forename: Greg C
authors.initials: GC
authors.lastname: Flaker
authors.forename: Kerry L
authors.initials: KL
authors.lastname: Lee
authors.forename: Michael O
authors.initials: MO
authors.lastname: Sweeney
authors.forename: Gervasio A
authors.initials: GA
authors.lastname: Lamas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects*; D005260:Female; D006333:Heart Failure / Q000209:etiology* / Q000401:mortality; D006760:Hospitalization; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D016016:Proportional Hazards Models; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000209:etiology