title: Role of echocardiography before cardiac resynchronization therapy: new advances and current developments.
abstract: The role of echocardiography in improving the selection of patients who will benefit from cardiac resynchronization therapy (CRT) remains a source of debate. Although previous landmark reports have demonstrated a link between mechanical dyssynchrony, assessed by delays between left ventricle (LV) walls and response to CRT, the predictive value of these findings has not yet been confirmed in multicenter trials. Indeed, recent studies demonstrated that the classical assessment of LV mechanical dyssynchrony using delay between walls by echocardiography depends not only on LV electrical activation delay (electrical dyssynchrony), but also on abnormalities in regional contractility of the LV and/or loading conditions, which do not represent an appropriate target for CRT. Recent reports highlighted the value of new indices of electromechanical dyssynchrony obtained by echocardiography, to predict LV response and outcome after CRT including septal flash, left bundle branch block-typical pattern by longitudinal strain, apical rocking, septal strain patterns, and systolic stretch index. This was achieved using a mechanistic approach, based on the contractile consequences of electrical dyssynchrony. These indices are rarely found in patients with narrow QRS (<120 ms), whereas their frequency rises in patients with an increase in QRS duration (>120 ms). Theses indices should improve candidate selection for CRT in clinical practice, especially for patients in whom the benefit of CRT remains uncertain, for example, patients with intermediate QRS width (120-150 ms).
authors: Lille North of France University/Catholic University Hospital/Catholic School of Medicine, Cardiology Department, Lille Catholic University, Lille, France.|INSERM U 1088, University of Picardie, Amiens, France.
authors: Sylvestre
authors: S
authors: Marechaux
authors: Lille North of France University/Catholic University Hospital/Catholic School of Medicine, Cardiology Department, Lille Catholic University, Lille, France.|INSERM U 1088, University of Picardie, Amiens, France.
authors: Aymeric
authors: A
authors: Menet
authors: Lille North of France University/Catholic University Hospital/Catholic School of Medicine, Cardiology Department, Lille Catholic University, Lille, France.
authors: Yves
authors: Y
authors: Guyomar
authors: Cardiology Department, Grenoble University Hospital, Grenoble, France.
authors: Pierre-Vladimir
authors: PV
authors: Ennezat
authors: Cardiology Department, Grenoble University Hospital, Grenoble, France.|Cardiovascular and Thoracic Department, Amiens University Hospital, Amiens, France.
authors: Raphaëlle Ashley
authors: RA
authors: Guerbaai
authors: Lille North of France University/Catholic University Hospital/Catholic School of Medicine, Cardiology Department, Lille Catholic University, Lille, France.
authors: Pierre
authors: P
authors: Graux
authors: INSERM U 1088, University of Picardie, Amiens, France.|Cardiovascular and Thoracic Department, Amiens University Hospital, Amiens, France.
authors: Christophe
authors: C
authors: Tribouilloy
mesh_terms: D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy; D004452:Echocardiography / Q000639:trends*; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D011237:Predictive Value of Tests
keywords: 
  EKG
  ; cardiac resynchronization therapy; echocardiography; heart failure; outcome; speckle tracking