title: Influence of automatic frequent pace-timing adjustments on effective left ventricular pacing during cardiac resynchronization therapy.
abstract: OBJECTIVE
  Cardiac resynchronization therapy (CRT) requires effective left ventricular (LV) pacing (i.e. sufficient energy and appropriate timing to capture). The AdaptivCRT™ (aCRT) algorithm serves to maintain ventricular fusion during LV or biventricular pacing. This function was tested by comparing the morphological consistency of ventricular depolarizations and percentage effective LV pacing in CRT patients randomized to aCRT vs. echo-optimization.
  
  
  RESULTS
  Continuous recordings (≥20 h) of unipolar LV electrograms from aCRT (n = 38) and echo-optimized patients (n = 22) were analysed. Morphological consistency was determined by the correlation coefficient between each beat and a template beat. Effective LV pacing of paced beats was assessed by algorithmic analysis of negative initial EGM deflection in each evoked response. The %CRT pacing delivered, %effective LV pacing (i.e. % of paced beats with effective LV pacing), and overall %effective CRT (i.e. product of %CRT pacing and %effective LV pacing) were compared between aCRT and echo-optimized patients. Demographics were similar between groups. The mean correlation coefficient between individual beats and template was greater for aCRT (0.96 ± 0.03 vs. 0.91 ± 0.13, P = 0.07). Although %CRT pacing was similar for aCRT and echo-optimized (median 97.4 vs. 98.6%, P = 0.14), %effective LV pacing was larger for aCRT [99.6%, (99.1%, 99.9%) vs. 94.3%, (24.3%, 99.8%), P=0.03]. For aCRT vs. echo-optimized groups, the proportions of patients with ≥90% effective LV pacing was 92 vs. 55% (P = 0.002), and with ≥90% effective CRT was 79 vs. 45%, respectively (P = 0.018).
  
  
  CONCLUSIONS
  AdaptivCRT™ significantly increased effective LV pacing over echo-optimized CRT.
authors.affiliation: Cleveland Clinic Main Campus, Mail Code J2-2, 9500 Euclid Ave., Cleveland, OH 44195, USA.
authors.forename: Niraj
authors.initials: N
authors.lastname: Varma
authors.affiliation: Medtronic PLC, 8200 Coral Sea St., Mail Stop: MVN41, Mounds View, MN 55112, USA.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Stadler
authors.affiliation: Medtronic PLC, 8200 Coral Sea St., Mail Stop: MVN41, Mounds View, MN 55112, USA.
authors.forename: Subham
authors.initials: S
authors.lastname: Ghosh
authors.affiliation: Department of Cardiology and Angiology, Ruhr-Universität Bochum, Bochum, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Kloppe
mesh_terms: D000465:Algorithms; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000517:prevention & control*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013813:Therapy, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome; D014481:United States
keywords: Cardiac resynchronization therapy; Effective LV pacing; Electrograms; Per cent pacing