title: Paced QT interval as a risk factor for new-onset left ventricular systolic dysfunction and cardiac death after permanent pacemaker implantation.
abstract: BACKGROUND
  Prolongation of corrected QT (QTc) interval reflects an increased risk of fatal arrhythmia and cardiac death in various populations. However, it is not clear whether the paced-QTc (p-QTc) interval is associated with new-onset left ventricular systolic dysfunction (new-LVSD) or cardiac death.
  
  
  METHODS
  In 491 consecutive patients (64 ± 14 years) with preserved LV ejection fraction (64 ± 7%), the p-QTc interval was measured within 2 weeks after PPM implantation. We assessed the rates of new-LVSD and cardiac death based on the degree of p-QTc interval.
  
  
  RESULTS
  During the follow-up period (78 ± 51 months), new-LVSD and cardiac death were identified in 53 (10.8%) and 26 (5.3%) patients, respectively. Patients with new-LVSD had more frequent atrioventricular block (P=0.041), a higher percentage of ventricular pacing (P=0.005), a longer p-QRS duration (P<0.001), and more prolonged p-QTc interval (P<0.001) compared to those without new-LVSD. There was a graded increase in the rates of new-LVSD (P<0.001) and cardiac death (P=0.001) from the patients in the lowest to those in the highest tertile of the p-QTc interval. Additionally, the incidence of cardiac death was significantly elevated especially in the patients with new-LVSD and wider p-QTc interval. In Cox regression analyses, the p-QTc interval was independently associated with new-LVSD and cardiac death even after adjusted with various relevant confounding factors.
  
  
  CONCLUSIONS
  Prolonged p-QTc interval was closely associated with new-LVSD and cardiac death after PPM implantation in patients with preserved LV systolic function. The rate of cardiac death significantly increased especially in patients who showed more p-QTc widening along with new-LVSD.
authors.affiliation: Cardiology Clinic, National Cancer Center, Gyeonggi-do, Republic of Korea.
authors.forename: Eun Jeong
authors.initials: EJ
authors.lastname: Cho
authors.affiliation: Department of Medicine, Heart, Vascular, and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. Electronic address: orthovics@skku.edu.
authors.forename: Seung-Jung
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Department of Medicine, Heart, Vascular, and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Kyoung Min
authors.initials: KM
authors.lastname: Park
authors.affiliation: Department of Medicine, Heart, Vascular, and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Young Keun
authors.initials: YK
authors.lastname: On
authors.affiliation: Department of Medicine, Heart, Vascular, and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: June Soo
authors.initials: JS
authors.lastname: Kim
mesh_terms: D000368:Aged; D003643:Death; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D011183:Postoperative Complications / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D018487:Ventricular Dysfunction, Left / Q000453:epidemiology*
keywords: Cardiac death; Paced-QTc interval; Permanent pacemaker; Systolic dysfunction