title: Use of phase analysis of gated SPECT perfusion imaging to quantify dyssynchrony in patients with mild-to-moderate left ventricular dysfunction.
abstract: BACKGROUND
  CRT has been shown to be beneficial in the majority of patients with NYHA class III-IV symptoms, prolonged QRS duration, and an EF < or =35%. The use of imaging modalities to quantify dyssynchrony may help identify patients who may benefit from CRT, but do not meet current selection criteria. We hypothesize that patients with mild-to-moderate LV dysfunction have significant degrees of mechanical dyssynchrony.
  
  
  METHODS
  We compared phase analysis measures of mechanical dyssynchrony from gated SPECT imaging in patients with mild-to-moderate LV dysfunction (EF 35-50%, n = 93), with patients with severe LV dysfunction (EF < or = 35%, n = 167), and with normal controls (EF > or = 55%, n = 75). Furthermore, we evaluated the relationships between QRS duration and dyssynchrony and determined the prevalence of dyssynchrony in patients with mild-moderate LV dysfunction.
  
  
  RESULTS
  Patients with mild-moderate LV dysfunction have more dyssynchrony than normal controls (phase SD 37.7 degrees vs 8.8 degrees , P < .001 and bandwidth 113.5 degrees vs 28.7 degrees , P < .001), but less dyssynchrony than patients with severe LV dysfunction (phase SD 37.7 degrees vs 52.0 degrees , P < .001 and bandwidth 113.5 degrees vs 158.2 degrees , P < .001). In the cohort of patients with LV EF 35-50%, there were only weak correlations between QRS duration and dyssynchrony (phase SD, r = 0.28 and bandwidth, r = 0.20). There were 73 patients with LVEF 35-50% and QRS duration <120 milliseconds of which 21 (28.8%) had mechanical dyssynchrony. Overall, 37% of patients with mild-to-moderate LV dysfunction had significant degrees of mechanical dyssynchrony.
  
  
  CONCLUSIONS
  This is the largest reported study evaluating mechanical dyssynchrony in patients with mild-moderate LV dysfunction using phase analysis of gated SPECT imaging. In this study, approximately one-third of patients with mild-to-moderate LV dysfunction had significant LV mechanical dyssynchrony. With further study, phase analysis of gated SPECT imaging may help improve patient selection for CRT.
authors.affiliation: Division of Cardiology, Duke University Medical Center, Durham, NC, USA.
authors.forename: Allen E
authors.initials: AE
authors.lastname: Atchley
authors.forename: Mark A
authors.initials: MA
authors.lastname: Trimble
authors.forename: Zainab
authors.initials: Z
authors.lastname: Samad
authors.forename: Linda K
authors.initials: LK
authors.lastname: Shaw
authors.forename: Robert
authors.initials: R
authors.lastname: Pagnanelli
authors.forename: Ji
authors.initials: J
authors.lastname: Chen
authors.forename: Ernest V
authors.initials: EV
authors.lastname: Garcia
authors.forename: Ami E
authors.initials: AE
authors.lastname: Iskandrian
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Velazquez
authors.forename: Salvador
authors.initials: S
authors.lastname: Borges-Neto
mesh_terms: D000368:Aged; D000465:Algorithms; D005260:Female; D015637:Gated Blood-Pool Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging*
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