title: Long-term follow-up results of the pacing to avoid cardiac enlargement (PACE) trial.
abstract: OBJECTIVE
  We report the results of long-term follow-up of the Pacing to Avoid Cardiac Enlargement (PACE) trial, a prospective, double-blinded, randomized, multicentre study that confirmed the superiority of biventricular (BiV) pacing compared with right ventricular apical (RVA) pacing in prevention of LV adverse remodelling and deterioration of systolic function at 1 and 2 years.
  
  
  RESULTS
  Patients with bradycardia and preserved LVEF were randomized to receive RVA (n = 88) or BiV pacing (n = 89). Co-primary endpoints were LV end-systolic volume (LVESV) and LVEF measured by echocardiography. There were 149 patients who had extended follow-up, with a mean duration of 4.8 ± 1.5 years (2.5-7.8 years). The primary endpoint analyses were performed in 146 patients (74 in the RVA group and 72 in the BiV group). In the RVA pacing group, the LVEF decreased while the LVESV increased progressively at follow-up, but remained unchanged in the BiV pacing group. The differences in LVEF between the RVA and BiV groups were -6.3, -9.2, and -10.7% at 1-year, 2-year, and long-term follow-up, respectively (all P < 0.001). The corresponding differences in LVESV were +7.4, +9.9, and +13.1 mL, respectively (all P < 0.001). The deleterious effects of RVA pacing consistently occurred in all the pre-defined subgroups. Furthermore, patients with RVA pacing had a significantly higher prevalence of heart failure hospitalization than the BiV group (23.9% vs. 14.6%, log-rank χ²  = 7.55, P  = 0.006).
  
  
  CONCLUSIONS
  Left ventricular adverse remodelling and deterioration of systolic function continued at long-term follow-up in patients with RVA pacing; this deterioration was prevented by the use of BiV pacing. Also, heart failure hospitalization was more prevalent in the RVA pacing group.
authors.affiliation: 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, Hong Kong.
authors.forename: Cheuk-Man
authors.initials: CM
authors.lastname: Yu
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.forename: Xiu-Xia
authors.initials: XX
authors.lastname: Luo
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhang
authors.forename: Hussin
authors.initials: H
authors.lastname: Azlan
authors.forename: Omar
authors.initials: O
authors.lastname: Razali
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D006332:Cardiomegaly / Q000000981:diagnostic imaging / Q000209:etiology / Q000517:prevention & control*; D004311:Double-Blind Method; D004452:Echocardiography; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D011446:Prospective Studies; D013318:Stroke Volume / Q000502:physiology; D013997:Time Factors; D016896:Treatment Outcome; D020257:Ventricular Remodeling / Q000502:physiology*
keywords: Bradycardia; Left ventricular remodelling; Long-term follow-up; Pacing