title: Electrical dyssynchrony induced by biventricular pacing: implications for patient selection and therapy improvement.
abstract: BACKGROUND
  Biventricular pacing (BVP) may not achieve complete electrical resynchronization.
  
  
  OBJECTIVE
  The purpose of this study was to assess whether the resynchronizing effect of BVP varies among patients depending on the underlying electrical substrate.
  
  
  METHODS
  High-resolution electrocardiographic mapping with invasive measurement of the maximal rate of systolic left ventricular (LV) pressure rise (LVdP/dtmax) was performed during baseline activation and during BVP in 61 patients with heart failure with various conduction delays: 13 with narrow QRS duration (<120 ms), 22 with nonspecific intraventricular conduction disturbance, and 26 with left bundle branch block. Electrical dyssynchrony, both during baseline activation and BVP, was quantified by total and LV activation times (TAT and LVTAT) and by ventricular electrical uncoupling (VEU = mean LVTAT - mean right ventricular activation time). Response to BVP was defined as a ≥10% increase in LVdP/dtmax.
  
  
  RESULTS
  The electrical activation pattern during BVP was similar for all patient groups and, hence, not dependent on baseline conduction disturbance. During BVP, TAT, LVTAT, and VEU were similar for all groups and were either not correlated or weakly correlated with the change in LVdP/dtmax. In contrast, changes in electrical dyssynchrony correlated significantly with the change in LVdP/dtmax: r=0.71, 0.69, and 0.69 for ∆TAT, ∆LVTAT, and ∆VEU, respectively (all P < .001). Responders showed higher baseline dyssynchrony levels and BVP-induced dyssynchrony reduction than did nonresponders (all P < .001); in nonresponders, BVP worsened activation times than did baseline activation.
  
  
  CONCLUSIONS
  BVP does not eliminate electrical dyssynchrony, but rather brings it to a common level independent of the patient's underlying electrical substrate. Therefore, BVP is of benefit to patients with dyssynchrony but not to patients with insufficient electrical dyssynchrony in whom it induces an iatrogenic electropathy.
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université Bordeaux, IHU LIRYC, Bordeaux, France. Electronic address: sylvain.ploux@gmail.com.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Ploux
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université Bordeaux, IHU LIRYC, Bordeaux, France.
authors.forename: Romain
authors.initials: R
authors.lastname: Eschalier
authors.affiliation: Imperial College London, London, United Kingdom.
authors.forename: Zachary I
authors.initials: ZI
authors.lastname: Whinnett
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université Bordeaux, IHU LIRYC, Bordeaux, France; Maastricht University, Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands.
authors.forename: Joost
authors.initials: J
authors.lastname: Lumens
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université Bordeaux, IHU LIRYC, Bordeaux, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Derval
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université Bordeaux, IHU LIRYC, Bordeaux, France.
authors.forename: Frederic
authors.initials: F
authors.lastname: Sacher
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université Bordeaux, IHU LIRYC, Bordeaux, France.
authors.forename: Mélèze
authors.initials: M
authors.lastname: Hocini
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université Bordeaux, IHU LIRYC, Bordeaux, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Jaïs
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université Bordeaux, IHU LIRYC, Bordeaux, France.
authors.forename: Remi
authors.initials: R
authors.lastname: Dubois
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université Bordeaux, IHU LIRYC, Bordeaux, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Ritter
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université Bordeaux, IHU LIRYC, Bordeaux, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Haïssaguerre
authors.affiliation: Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Wilkoff
authors.affiliation: Imperial College London, London, United Kingdom.
authors.forename: Darrel P
authors.initials: DP
authors.lastname: Francis
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université Bordeaux, IHU LIRYC, Bordeaux, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Bordachar
mesh_terms: D000328:Adult; D000368:Aged; D002037:Bundle-Branch Block / Q000209:etiology / Q000503:physiopathology; D058406:Cardiac Resynchronization Therapy / Q000009:adverse effects* / Q000379:methods; D004562:Electrocardiography / Q000379:methods; D055724:Electrophysiological Phenomena; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006333:Heart Failure / Q000150:complications / Q000503:physiopathology / Q000628:therapy; D006352:Heart Ventricles / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D018579:Patient Selection; D018570:Risk Assessment
keywords: Cardiac resynchronization therapy; Electrocardiographic mapping; Heart failure; Hemodynamic; Left bundle branch block; Nonspecific intraventricular conduction disturbance; Pacing