title: A U-shaped type II contraction pattern in patients with strict left bundle branch block predicts super-response to cardiac resynchronization therapy.
abstract: BACKGROUND
  New criteria to define strict left bundle branch block (LBBB) on the basis of pathophysiological principles predict response to cardiac resynchronization therapy (CRT). Heterogeneous activation and contraction patterns have been identified in patients with classical LBBB. Cardiac magnetic resonance (CMR) imaging has demonstrated that a U-shaped (type II) contraction predicts reverse remodeling post-CRT. A homogeneous spread of (type I) contraction is less predictive.
  
  
  OBJECTIVE
  The purpose of this study was to investigate contraction patterns among patients with strict LBBB and to test whether a type II contraction pattern better predicts CRT response and super-response.
  
  
  METHODS
  Thirty-seven patients with strict LBBB (QRS duration ≥140 ms for men and ≥130 ms for women with mid-QRS notching or slurring in ≥2 contiguous leads) underwent cine CMR imaging pre-CRT with an analysis of their contraction patterns by using endocardial contour tracking software. Patients were evaluated for reverse remodeling 6 months postimplantation.
  
  
  RESULTS
  Nineteen patients (51%) had a type II contraction pattern. A total of 25 patients (68%) of the cohort reverse remodeled. In the type II contraction group, all 19 patients (100%) reverse remodeled as compared with 6 patients (33%) in the type I contraction group (P < .01). Super-response was achieved in 21 patients (57%) of the total cohort: 5 patients with a type I contraction pattern (28%) and 16 patients with a type II contraction pattern (84%) (P < .01).
  
  
  CONCLUSIONS
  Patients with strict LBBB who are guideline indicated for CRT have heterogeneous contraction patterns derived from cine CMR. A type II contraction pattern is strongly predictive for reverse remodeling and super-response. This questions whether strict LBBB criteria alone are sufficient to reliably predict a positive response to CRT.
authors.affiliation: King's College London, London, United Kingdom. Electronic address: thomas.jackson@kcl.ac.uk.
authors.forename: Tom
authors.initials: T
authors.lastname: Jackson
authors.affiliation: King's College London, London, United Kingdom.
authors.forename: Manav
authors.initials: M
authors.lastname: Sohal
authors.affiliation: King's College London, London, United Kingdom.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Chen
authors.affiliation: King's College London, London, United Kingdom.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Child
authors.affiliation: King's College London, London, United Kingdom.
authors.forename: Eva
authors.initials: E
authors.lastname: Sammut
authors.affiliation: Guy's and St. Thomas' Hospitals, London, United Kingdom.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Behar
authors.affiliation: Guy's and St. Thomas' Hospitals, London, United Kingdom.
authors.forename: Simon
authors.initials: S
authors.lastname: Claridge
authors.affiliation: Guy's and St. Thomas' Hospitals, London, United Kingdom.
authors.forename: Gerald
authors.initials: G
authors.lastname: Carr-White
authors.affiliation: King's College London, London, United Kingdom.
authors.forename: Reza
authors.initials: R
authors.lastname: Razavi
authors.affiliation: King's College London, London, United Kingdom; Guy's and St. Thomas' Hospitals, London, United Kingdom.
authors.forename: Christopher Aldo
authors.initials: CA
authors.lastname: Rinaldi
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology*; D013318:Stroke Volume; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology*; D020257:Ventricular Remodeling / Q000502:physiology*
keywords: Cardiac magnetic resonance; Heart failure; Imaging; Left bundle branch block; Pacing; Resynchronization