title: Dyssynchrony, contraction efficiency and regional function with apical and non-apical RV pacing.
abstract: BACKGROUND
  Recent work has shown no difference in change of LVEF between RV apical (RVA) pacing and non-RVA pacing in patients with normal LV function. We hypothesised that a more sensitive marker (global longitudinal strain, GLS) could identify a detrimental effect of RVA and that assessment of deformation could identify whether dyssynchrony, contraction inefficiency and regional LV impairment were responsible for functional changes.
  
  
  METHODS
  In this substudy of Protect-PACE (The Protection of Left Ventricular Function During Right Ventricular Pacing. Does Right Ventricular High-septal Pacing Improve Outcome Compared With Right Ventricular Apical Pacing?), a randomised controlled trial of RVA and non-RVA pacing in pacemaker-dependent patients with preserved EF, 145 patients (76 with RVA) with echocardiograms of sufficient quality underwent measurement of LV longitudinal strain (GLS) from speckle tracking just after implantation and at 2 years. LV dyssynchrony, discoordination and regional apical longitudinal strain were also measured.
  
  
  RESULTS
  Pacing was associated with reduced GLS after 2 years, although 2-year GLS was lower in RVA (-13.9 ± 4.1 vs -15.5 ± 4.6, p = 0.02). RVA was an independent correlate of ΔGLS, although there was a minor difference in ΔGLS between the RVA and non-RVA groups (-1.8 ± 3.6 vs -0.8 ± 3.4%, p= 0.07), reflecting impairment of GLS at baseline in RVA. Apical strain was significantly lower in RVA than those in non-RVA at baseline and 2 years (both p < 0.01). Dyssynchrony and discoordination parameters at 2 years also showed significant deterioration in RVA. Apical strain, dyssynchrony and discoordination parameters at 2 years were significantly associated with ΔGLS.
  
  
  CONCLUSIONS
  Inefficient dyssynchronous contraction and the decrease in apical strain appear to be associated with global LV impairment in RVA.
  
  
  BACKGROUND
  PROTECT-PACE ClinicalTrials.gov number NCT00461734.
authors: Menzies Institute for Medical Research, Hobart, Tasmania, Australia.
authors: Makoto
authors: M
authors: Saito
authors: Princess Alexandra Hospital, Brisbane, Queensland, Australia University of Queensland, Brisbane, QLD 4072.
authors: Gerry
authors: G
authors: Kaye
authors: Menzies Institute for Medical Research, Hobart, Tasmania, Australia.
authors: Kazuaki
authors: K
authors: Negishi
authors: James Cook University Hospital, Cleveland, UK.
authors: Nick
authors: N
authors: Linker
authors: University of Birmingham, Birmingham, UK.
authors: Michael
authors: M
authors: Gammage
authors: Menzies Institute for Medical Research, Hobart, Tasmania, Australia Wroclaw Medical University, Wroclaw, Poland.
authors: Wojciech
authors: W
authors: Kosmala
authors: Menzies Institute for Medical Research, Hobart, Tasmania, Australia.
authors: Thomas H
authors: TH
authors: Marwick
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D054537:Atrioventricular Block / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004452:Echocardiography / Q000379:methods; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology*; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D016037:Single-Blind Method; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology; D016278:Ventricular Function, Right / Q000502:physiology