title: Paced QT interval is a better predictor of mortality than the intrinsic QT interval: long-term follow-up study.
abstract: BACKGROUND
  Prolongation of the corrected QT (QTc) interval on 12-lead electrocardiogram is related to total mortality and sudden cardiac death. The value of the paced QTc interval in predicting mortality has not been investigated.
  
  
  OBJECTIVE
  To evaluate the relationship between the paced QTc interval and mortality.
  
  
  METHODS
  Of 1440 patients who underwent pacemaker implantation from January 1990 to March 2010, 766 had a recorded intrinsic and ventricular paced rhythm and were included in this study. The intrinsic and paced QTc intervals were measured on 12-lead electrocardiogram before and 1-month after implantation.
  
  
  RESULTS
  During a mean follow-up period of 7 ± 5 years, 189 (24.4%) patients died, of which 63 (8.1%) were cardiac deaths. Compared with patients in the first tertile of the paced QTc interval (<484 ms), patients in the third tertile (>511 ms) were significantly more likely to die (19% vs 29%; P < .05). A comparison of the third and first tertiles of the QTc interval showed that a prolonged paced QTc interval was a significant independent predictor of all-cause mortality (adjusted hazard ratio 2.08; 95% confidence interval 1.44-3.01; P < .001) and cardiac mortality (adjusted hazard ratio 2.53; 95% confidence interval 1.29-4.95; P = .007) and a better predictor than was a prolonged intrinsic QTc interval. When treated as a continuous variable, a prolonged paced QTc interval predicted increased total mortality and cardiac mortality.
  
  
  CONCLUSIONS
  The paced QTc interval appears to be a more useful marker in predicting bad prognosis than does the intrinsic QTc interval in patients with indications for a permanent pacemaker.
authors.affiliation: Division of Cardiology, Cardiovascular Center, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jung Myung
authors.initials: JM
authors.lastname: Lee
authors.affiliation: South Denver Cardiology Associates, Littleton, Colorado.
authors.forename: Ajit H
authors.initials: AH
authors.lastname: Janardhan
authors.affiliation: Division of Cardiology, Eulji University Hospital, Daejeon, Korea.
authors.forename: Ki-Woon
authors.initials: KW
authors.lastname: Kang
authors.affiliation: Division of Cardiology, Cardiovascular Center, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Boyoung
authors.initials: B
authors.lastname: Joung
authors.affiliation: Division of Cardiology, Cardiovascular Center, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hui-Nam
authors.initials: HN
authors.lastname: Pak
authors.affiliation: South Denver Cardiology Associates, Littleton, Colorado.
authors.forename: Srikanth
authors.initials: S
authors.lastname: Sundaram
authors.affiliation: South Denver Cardiology Associates, Littleton, Colorado.
authors.forename: William C
authors.initials: WC
authors.lastname: Choe
authors.affiliation: Division of Cardiology, Cardiovascular Center, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Moon-Hyoung
authors.initials: MH
authors.lastname: Lee
authors.affiliation: Division of Cardiology, Cardiovascular Center, Yonsei University College of Medicine, Seoul, Korea. Electronic address: hyejin@yuhs.ac.
authors.forename: Hye Jin
authors.initials: HJ
authors.lastname: Hwang
mesh_terms: D000328:Adult; D000368:Aged; D016757:Death, Sudden, Cardiac / Q000453:epidemiology*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D015994:Incidence; D008133:Long QT Syndrome / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial / Q000009:adverse effects*; D011379:Prognosis; D056910:Republic of Korea; D012307:Risk Factors; D016019:Survival Analysis
keywords: Intrinsic QTc interval; Mortality; Paced QTc interval; Permanent pacemaker; Prolonged QTc interval; Ventricular pacing