title: Left ventricular systolic asynchrony after acute myocardial infarction in patients with narrow QRS complexes.
abstract: BACKGROUND
  The aim of the study was to assess the degree of left ventricular (LV) asynchrony after myocardial infarction (MI) in patients with a narrow QRS complex using tissue Doppler imaging (TDI) and correlate this with the site and extent of the infarction measured by contrast-enhanced magnetic resonance imaging (Ce-MRI).
  
  
  METHODS
  Echocardiography with TDI and Ce-MRI was performed within 6 days of acute MI in 47 patients and compared with 69 age-matched healthy volunteers. Regional myocardial velocities were assessed in 12 segments, and the corresponding systolic velocity (Sm), early diastolic velocity (Em), as well as the time to peak Sm (Ts) and time to peak Em (Te) were measured. To assess LV synchronicity, SDs of Ts (Ts-SD) and Te (Te-SD) of all 12 segments were computed. Location and size of infarct were confirmed by Ce-MRI with a 16-segment model.
  
  
  RESULTS
  All the patients had a normal QRS complex duration. The Ts-SD was significantly prolonged in the MI group when compared with controls (42.2 +/- 13.7 vs 18.0 +/- 7.0 milliseconds, P < .001). The Ts-SD was longer in patients with anterior than inferior MI (46.8 +/- 13.9 vs 34.6 +/- 8.5 milliseconds, P = .002). Stepwise multiple regression analysis revealed that infarct size was the main independent predictor of systolic asynchrony ( B = 0.79, 95% CI 0.75-1.23, P < .001). Asynchrony was not related to the transmurality of the infarction.
  
  
  CONCLUSIONS
  Myocardial infarction has a significant impact on LV synchronicity even in those with a narrow QRS complex. The degree of LV systolic asynchrony is mainly determined by the infarct size and not transmurality.
authors.affiliation: Division of Cardiology, Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Anna K Y
authors.initials: AK
authors.lastname: Chan
authors.forename: Cheuk-Man
authors.initials: CM
authors.lastname: Yu
authors.forename: Wynnie W M
authors.initials: WW
authors.lastname: Lam
authors.forename: Gabriel W K
authors.initials: GW
authors.lastname: Yip
authors.forename: Wing-Hong
authors.initials: WH
authors.lastname: Fung
authors.forename: Nina M C
authors.initials: NM
authors.lastname: So
authors.forename: Mei
authors.initials: M
authors.lastname: Wang
authors.forename: John E
authors.initials: JE
authors.lastname: Sanderson
mesh_terms: D003287:Contrast Media / Q000032:analysis; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000503:physiopathology*; D015588:Observer Variation; D012044:Regression Analysis; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000503:physiopathology*
chemical_list: D003287:Contrast Media