title: Improved relationship between left and right ventricular electrical activation after cardiac resynchronization therapy in heart failure patients can be quantified by body surface potential mapping.
abstract: OBJECTIVE
  Few studies have evaluated cardiac electrical activation dynamics after cardiac resynchronization therapy. Although this procedure reduces morbidity and mortality in heart failure patients, many approaches attempting to identify the responders have shown that 30% of patients do not attain clinical or functional improvement. This study sought to quantify and characterize the effect of resynchronization therapy on the ventricular electrical activation of patients using body surface potential mapping, a noninvasive tool.
  
  
  METHODS
  This retrospective study included 91 resynchronization patients with a mean age of 61 years, left ventricle ejection fraction of 28%, mean QRS duration of 182 ms, and functional class III/IV (78%/22%); the patients underwent 87-lead body surface mapping with the resynchronization device on and off. Thirty-six patients were excluded. Body surface isochronal maps produced 87 maximal/mean global ventricular activation times with three regions identified. The regional activation times for right and left ventricles and their inter-regional right-to-left ventricle gradients were calculated from these results and analyzed. The Mann-Whitney U-test and Kruskall-Wallis test were used for comparisons, with the level of significance set at p≤0.05.
  
  
  RESULTS
  During intrinsic rhythms, regional ventricular activation times were significantly different (54.5 ms vs. 95.9 ms in the right and left ventricle regions, respectively). Regarding cardiac resynchronization, the maximal global value was significantly reduced (138 ms to 131 ms), and a downward variation of 19.4% in regional-left and an upward variation of 44.8% in regional-right ventricular activation times resulted in a significantly reduced inter-regional gradient (43.8 ms to 17 ms).
  
  
  CONCLUSIONS
  Body surface potential mapping in resynchronization patients yielded electrical ventricular activation times for two cardiac regions with significantly decreased global and regional-left values but significantly increased regional-right values, thus showing an attenuated inter-regional gradient after the cardiac resynchronization therapy.
authors.affiliation: Faculdade de Medicina, Heart Institute (InCor), Hospital das Clínicas, Universidade de São Paulo, São Paulo, SP, Brazil. nsamesima@gmail.com
authors.forename: Nelson
authors.initials: N
authors.lastname: Samesima
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Pastore
authors.forename: Roberto Andrés
authors.initials: RA
authors.lastname: Douglas
authors.forename: Martino Filho
authors.initials: MF
authors.lastname: Martinelli
authors.forename: Anísio A
authors.initials: AA
authors.lastname: Pedrosa
mesh_terms: D000368:Aged; D018780:Body Surface Potential Mapping / Q000379:methods*; D002037:Bundle-Branch Block / Q000503:physiopathology; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D004599:Electric Stimulation Therapy; D005260:Female; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology; D016278:Ventricular Function, Right / Q000502:physiology
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