title: Sites of latest mechanical activation as assessed by SPECT myocardial perfusion imaging in ischemic and dilated cardiomyopathy patients with LBBB.
abstract: OBJECTIVE
  Sites of latest mechanical activation (SOLA) have been recognized as optimal left-ventricular (LV) lead positions for cardiac resynchronization therapy (CRT). This study was aimed to investigate SOLA in ischemic cardiomyopathy (ICM) and dilated cardiomyopathy (DCM) patients with left bundle branch block (LBBB).
  
  
  METHODS
  Sixty-four consecutive LBBB patients (47 DCM, 17 ICM), who met the standard indications for CRT and underwent resting SPECT myocardial perfusion imaging (MPI), were selected. Phase analysis was used to assess LV dyssynchrony and SOLA. The Emory Cardiac Toolbox was used to measure perfusion defects. LV dyssynchrony and SOLA were compared between the DCM patients with wide (≥150 ms) and moderate (120-150 ms) QRS durations (QRSd). The relationship between SOLA and perfusion defects was analyzed in the ICM patients.
  
  
  RESULTS
  The DCM patients with wide QRSd had significantly more LV dyssynchrony than those with moderate QRSd. Lateral SOLA were significantly more frequent in the DCM patients with wide QRSd than those with moderate QRSd (96% vs. 62%, p = 0.010). In the ICM patients, SOLA were either in the scar segments (82%) or in the segments immediately adjacent to the scar segments (18%), regardless of QRSd.
  
  
  CONCLUSIONS
  Lateral SOLA were more frequent in the DCM patients with wide QRSd than those with moderate QRSd. Such relationship was not observed in the ICM patients, where SOLA were associated with scar location rather than QRSd. These findings support the use of SPECT MPI to aid the selection of potential CRT responders and guide LV lead placement.
authors.affiliation: Department of Cardiology, Anhui Medical University, 218 Jixi Road, Hefei, Anhui, 230022, China.
authors.forename: Xianhe
authors.initials: X
authors.lastname: Lin
authors.forename: Huiqin
authors.initials: H
authors.lastname: Xu
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Zhao
authors.forename: Ji
authors.initials: J
authors.lastname: Chen
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D055426:Cardiac-Gated Single-Photon Emission Computer-Assisted Tomography; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging / Q000628:therapy*; D055414:Myocardial Perfusion Imaging; D016277:Ventricular Function, Left