title: Left ventricular dyssynchrony in patients with left bundle branch block and patients after myocardial infarction: integration of mechanics and viability by cardiac magnetic resonance.
abstract: OBJECTIVE
  To quantify left ventricular (LV) dyssynchrony in patients with left bundle branch block (LBBB) and in patients after myocardial infarction (MI) applying an accelerated three-dimensional (3D) tagging cardiac magnetic resonance (CMR) technique, and to combine dyssynchrony information with viability data obtained by late gadolinium enhancement (LGE) CMR.
  
  
  RESULTS
  Thirty-two patients (59 +/- 11 years) after first MI (Pats(MI)), 10 patients (63 +/- 10 years) with LBBB (ejection fraction < 40%; Pats(LBBB<40)), 13 patients (63 +/- 11) with LBBB (ejection fraction >or= 40%; Pats(LBBB >or=40 )), and 15 healthy controls (53 +/- 10 years) underwent 3D tagging CMR and LGE imaging at 1.5 T. As a measure of mechanical LV dyssynchrony, the standard deviation of T(max) over the LV, the circumferential uniformity ratio estimate (CURE) index, and a segmental-based circumferential systolic dyssynchrony index (SDI) were calculated. All three parameters detected significantly increased circumferential dyssynchrony in patients compared with controls. The CURE and SDI showed a good correlation (r = 0.93, P < 0.0001) and detected most severe dyssynchrony in Pats(LBBB<40) (P < 0.001 vs. controls, P < 0.005 vs. Pats(MI)). Systolic dyssynchrony index additionally allowed integration of localized viability information to yield SDI(viable) which was highest in Pats(LBBB<40).
  
  
  CONCLUSIONS
  Dyssynchrony patterns in the LV can be quantified globally and regionally by 3D tagging CMR. Combination of viability and dyssynchrony information allows for a comprehensive dyssynchrony quantification in patients with LBBB or post-MI. Future studies are required to test the value of the method to predict responsiveness to resynchronization.
authors.affiliation: Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland.
authors.forename: Andrea K
authors.initials: AK
authors.lastname: Rutz
authors.forename: Robert
authors.initials: R
authors.lastname: Manka
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kozerke
authors.forename: Susanne
authors.initials: S
authors.lastname: Roas
authors.forename: Peter
authors.initials: P
authors.lastname: Boesiger
authors.forename: Juerg
authors.initials: J
authors.lastname: Schwitter
mesh_terms: D000328:Adult; D000368:Aged; D002037:Bundle-Branch Block / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D015588:Observer Variation; D018487:Ventricular Dysfunction, Left / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology