title: Deterioration of left ventricular systolic function in extended Pacing to Avoid Cardiac Enlargement (PACE) trial: the predictive value of early systolic dyssynchrony.
abstract: OBJECTIVE
  Biventricular (BiV) pacing was superior to right ventricular apical (RVA) pacing at extended follow-up in the Pacing to Avoid Cardiac Enlargement (PACE) trial. Early pacing-induced systolic dyssynchrony (DYS) might be related to mid-term result. However, it remains unknown whether early pacing-induced DYS can predict long-term reduction of left ventricular (LV) systolic function.
  
  
  RESULTS
  Patients with standard pacing indications and normal LV ejection fraction (LVEF) were randomized either to BiV (n = 89) or RVA (n = 88) pacing. Seventy-four patients in the RVA group and 72 in the BiV pacing group completed follow-up longer than 2 years. Serial echocardiography was performed with DYS assessed by tissue Doppler imaging, and the early pacing-induced DYS was defined as >33 ms by using standard deviation of the time to peak systolic velocity (Dyssynchrony Index) in a 12-segment model of LV at 1 month. There were 46 (32%) patients having early pacing-induced DYS that was more prevalent in the RVA pacing group than that in the BiV pacing group (50.7 vs. 12.3%, χ(2) = 25.1, P < 0.001) despite the similar DYS between the two groups at baseline (30 ± 13 vs. 26 ± 11 ms, P = 0.051). At a median follow-up of 4.8 years, patients developing early DYS had lower LVEF (53.2 ± 9.4 vs. 60.9 ± 8.0%, P < 0.001) and larger LV end-systolic volume (40.3 ± 23.7 vs. 29.3 ± 13.4 mL, P < 0.001) than those without DYS. Significant EF reduction (defined as ≥5%) occurred in 71.7% (33 in 46) of patients with DYS, but only in 30% (30 in 100) in those without DYS (χ(2) = 22.4, P < 0.001). Further analysis showed that both DYS at 1 month [odds ratio (OR): 3.113, P = 0.013] and RVA pacing (OR: 7.873, P < 0.001) independently predicted the deterioration of LV systolic function with pacing period of 4.8 years.
  
  
  CONCLUSIONS
  Early pacing-induced DYS is a significant predictor of reduction of LV systolic function for long-term pacing, which could be prevented by BiV pacing at relatively long-period follow-up.
  
  
  BACKGROUND
  Centre for Clinical Trials number, CUHK_CCT00037 (URL: http://www.cct.cuhk.edu.hk/Registry/publictrialrecord.aspx?trialid=CUHK_CCT00037).
authors: Division of Cardiology, Department of Medicine and Therapeutics, Institute of Vascular Medicine, Institute of Innovative Medicine, Heart Education And Research Training (HEART) Center, and Li Ka Shing Institute of Health Sciences, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR.
authors: Fang
authors: F
authors: Fang
authors: Division of Cardiology, Department of Medicine and Therapeutics, Institute of Vascular Medicine, Institute of Innovative Medicine, Heart Education And Research Training (HEART) Center, and Li Ka Shing Institute of Health Sciences, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR.
authors: Xiu-Xia
authors: XX
authors: Luo
authors: Department of Cardiology, West China Hospital, Sichuan University, Chengdu, China.
authors: Qing
authors: Q
authors: Zhang
authors: Department of Cardiology, National Heart Institute, Kuala Lumpur, Malaysia.
authors: Hussin
authors: H
authors: Azlan
authors: Department of Cardiology, National Heart Institute, Kuala Lumpur, Malaysia.
authors: Omar
authors: O
authors: Razali
authors: Department of Cardiology, Beijing Jishuitan Hospital, Peking University, Beijing, China.
authors: Zhan
authors: Z
authors: Ma
authors: Department of Ultrasound, Xiamen Zhongshan Hospital, Xiamen, China.
authors: Shu-Fen
authors: SF
authors: Gan
authors: Division of Cardiology, Department of Medicine and Therapeutics, Institute of Vascular Medicine, Institute of Innovative Medicine, Heart Education And Research Training (HEART) Center, and Li Ka Shing Institute of Health Sciences, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR.
authors: Jun-Min
authors: JM
authors: Xie
authors: Division of Cardiology, Department of Medicine and Therapeutics, Institute of Vascular Medicine, Institute of Innovative Medicine, Heart Education And Research Training (HEART) Center, and Li Ka Shing Institute of Health Sciences, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR professorcmyu@gmail.com.
authors: Cheuk-Man
authors: CM
authors: Yu
mesh_terms: D000368:Aged; D001919:Bradycardia / Q000175:diagnosis / Q000517:prevention & control*; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects*; D005260:Female; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000175:diagnosis / Q000209:etiology* / Q000517:prevention & control*; D008297:Male; D011379:Prognosis; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000209:etiology* / Q000517:prevention & control
keywords: Early pacing-induced systolic dyssynchrony; Heart failure; Long-term follow-up