title: Left ventricular mechanical dyssynchrony in patients with impaired left ventricular function undergoing gated SPECT myocardial perfusion imaging.
abstract: BACKGROUND
  Gated SPECT myocardial perfusion imaging (MPI) has been used to quantify mechanical dyssynchrony. Mechanical dyssynchrony appears to be related to response to cardiac resynchronization therapy.
  
  
  OBJECTIVE
  To evaluate the presence and predictors of mechanical dyssynchrony in patients with impaired left ventricular function (LVEF) ≤50%.
  
  
  METHODS
  The study included 143 consecutive patients referred for gated SPECT MPI with LVEF ≤50%. Gated SPECT MPI was performed according to a stress/rest protocol acquiring images with Tc 99m-tetrofosmin. Emory Cardiac Toolbox software was used for phase analysis and a standard deviation (SD) ≥43° was considered to indicate mechanical dyssynchrony.
  
  
  RESULTS
  Mechanical dyssynchrony was present in 53.1% of the patients. Its predictors were diabetes (OR 2.0, p≤0.05), summed stress score (OR 1.1, p≤0.0005), summed rest score (OR 1.1, p≤0.0001), end-diastolic volume (OR 1.0, p≤0.0001), LVEF (OR 0.9, p≤0.0001), LVEF ≤35% (OR 3.1, p≤0.005) and LVEF ≤35% and QRS ≥120 ms (OR 3.5, p≤0.05). In this study QRS width and QRS ≥120 ms were not predictors of mechanical dyssynchrony.
  
  
  CONCLUSIONS
  Myocardial perfusion imaging can be used to assess mechanical dyssynchrony. In patients with impaired ventricular function mechanical dyssynchrony was highly prevalent and was related to parameters of left ventricular function and perfusion.
authors.affiliation: Faculdade de Medicina, Universidade de Coimbra, Centro Hospitalar e Universitário de Coimbra (HUC), Serviço de Cardiologia, Coimbra, Portugal. mjvidigal@netc.pt
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Vidigal Ferreira
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Silva
authors.forename: Nuno
authors.initials: N
authors.lastname: Cabanelas
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Cunha
authors.forename: Domingos
authors.initials: D
authors.lastname: Ramos
authors.forename: Anabela
authors.initials: A
authors.lastname: Albuquerque
authors.forename: Rogério
authors.initials: R
authors.lastname: Teixeira
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Moreira
authors.forename: Gracinda
authors.initials: G
authors.lastname: Costa
authors.forename: João
authors.initials: J
authors.lastname: Lima
authors.forename: Luís Augusto
authors.initials: LA
authors.lastname: Providência
mesh_terms: D055426:Cardiac-Gated Single-Photon Emission Computer-Assisted Tomography; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D012189:Retrospective Studies; D018487:Ventricular Dysfunction, Left / Q000150:complications* / Q000000981:diagnostic imaging*