title: Characterization of mechanical dyssynchrony measured by gated single photon emission computed tomography phase analysis after acute ST-elevation myocardial infarction.
abstract: BACKGROUND
  Left ventricular dyssynchrony is an adverse consequence of ST-elevation myocardial infarction (STEMI) and bears an unfavorable prognosis. Mechanical dyssynchrony as measured by phase analysis from gated single photon emission computed tomography (GSPECT) correlates well with other imaging methods of assessing dyssynchrony but has not been studied in STEMI. We hypothesized that systolic dyssynchrony as measured by GSPECT would correlate with adverse remodeling after STEMI.
  
  
  METHODS
  In 28 subjects suffering STEMI, GSPECT with technetium-99m sestamibi was performed immediately after presentation (day 5) and remotely (6 months). Parameters of left ventricular dyssynchrony (QRS width, histogram bandwidth (HBW) and phase standard deviation (PSD)) were measured from GSPECT using the Emory Cardiac Toolbox. Left ventricular volumes, ejection fraction (LVEF) and infarct size were also assessed.
  
  
  RESULTS
  After successful primary percutaneous coronary intervention to the infarct-related artery, subjects had an LVEF of 46.4% ± 11% and a resting perfusion defect of 27.4% ± 16% at baseline. Baseline QRS width was normal (91.5 ± 17.5 ms). Subjects with STEMI had dyssynchrony compared with a cohort of 22 normal subjects (age 57.2 ± 10.6 years, <5% perfusion defect) by both HBW (100.3° ± 70.7° vs 26.5° ± 5.3°, P < .0001) and PSD (35.3° ± 16.9° vs 7.9° ± 2.1°, P < .0001). Baseline HBW correlated with resting perfusion defect size (r = 0.67, P < .001), end-systolic volume (r = 0.72, P < .001), end-diastolic volume (r = 0.63, P = .001), and inversely with LVEF (r = -0.74, P < .001). HBW and PSD improved over the follow-up period (-24.1 ± 35.9 degrees, P = .003 and -8.7° ± 14.6°, P = .006, respectively), and improvement in HBW correlated with reduction in LV end-systolic volumes (r = 0.43, P = .034). Baseline HBW and PSD, however, did not independently predict LVEF at 6 months follow-up.
  
  
  CONCLUSIONS
  After STEMI, subjects exhibit mechanical dyssynchrony as measured by GSPECT phase analysis without evidence of electrical dyssynchrony. Improvement in mechanical dyssynchrony correlates with beneficial ventricular remodeling. The full predictive value of this measure in post-infarct patients warrants further study.
authors: Emory University, Atlanta, GA, USA. jmurrow@emory.edu
authors: Jonathan
authors: J
authors: Murrow
authors: Fabio
authors: F
authors: Esteves
authors: James
authors: J
authors: Galt
authors: Ji
authors: J
authors: Chen
authors: Ernest
authors: E
authors: Garcia
authors: Ji
authors: J
authors: Lin
authors: Stamatios
authors: S
authors: Lerakis
authors: Salman
authors: S
authors: Sher
authors: F
authors: F
authors: Khan Pohlel
authors: Edmund K
authors: EK
authors: Waller
authors: Douglas
authors: D
authors: Vaughan
authors: Emerson
authors: E
authors: Perin
authors: James
authors: J
authors: Willerson
authors: Dean
authors: D
authors: Kereiakes
authors: Robert
authors: R
authors: Preti
authors: Andrew L
authors: AL
authors: Pecora
authors: Arshed A
authors: AA
authors: Quyyumi
mesh_terms: D000328:Adult; D000368:Aged; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D013599:Systole; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D016277:Ventricular Function, Left
chemical_list: D017256:Technetium Tc 99m Sestamibi