title: Impact of Cardiac Resynchronization Therapy on Left Ventricular Mechanics: Understanding the Response through a New Quantitative Approach Based on Longitudinal Strain Integrals.
abstract: BACKGROUND
  The mechanisms of improvement of left ventricular (LV) function with cardiac resynchronization therapy (CRT) are not yet elucidated. The aim of this study was to describe a new tool based on automatic quantification of the integrals of regional longitudinal strain signals and evaluate changes in LV strain distribution after CRT.
  
  
  METHODS
  This was a retrospective observational study of 130 patients with heart failure before CRT device implantation and after 3 to 6 months of follow-up. Integrals of regional longitudinal strain signals (from the beginning of the cardiac cycle to strain peak [IL,peak] and to the instant of aortic valve closure [IL,avc]) were analyzed retrospectively with custom-made algorithms. Response to CRT was defined as a decrease in LV end-systolic volume of ≥15%.
  
  
  RESULTS
  Responders (61%) and nonresponders (39%) showed similar baseline values of regional IL,peak and IL,avc. At follow-up, significant improvements of midlateral IL,peak and of midlateral IL,avc were noted only in responders. Midlateral IL,avc showed a relative increase of 151 ± 276% in responders, whereas a decrease of 33 ± 69% was observed in nonresponders. The difference between IL,avc and IL,peak (representing wasted energy of the LV myocardium) of the lateral wall showed a relative change of -59 ± 103% in responders between baseline and CRT, whereas in nonresponders, the relative change was 21 ± 113% (P = .009).
  
  
  CONCLUSIONS
  Strain integrals revealed changes between baseline and CRT in the lateral wall, demonstrating the beneficial effects of CRT on LV mechanics with favorable myocardial reverse remodeling.
authors.affiliation: Université de Rennes 1, LTSI, Rennes, France; INSERM, U1099, Rennes, France; Service de Cardiologie, CHU Tours, Tours, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Bernard
authors.affiliation: INSERM, U1099, Rennes, France; CIC-IT U 804, CHU Rennes, Université Rennes 1, Rennes, France; Service de Cardiologie, CHU Rennes, Rennes, France. Electronic address: erwan.donal@chu-rennes.fr.
authors.forename: Erwan
authors.initials: E
authors.lastname: Donal
authors.affiliation: INSERM, U1099, Rennes, France; CIC-IT U 804, CHU Rennes, Université Rennes 1, Rennes, France; Service de Cardiologie, CHU Rennes, Rennes, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Leclercq
authors.affiliation: Université de Rennes 1, LTSI, Rennes, France; INSERM, U1099, Rennes, France; Service de Médecine du Sport, CHU Rennes, Rennes, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Schnell
authors.affiliation: Service de Cardiologie, CHU Rennes, Rennes, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: Fournet
authors.affiliation: Université de Rennes 1, LTSI, Rennes, France; INSERM, U1099, Rennes, France.
authors.forename: Amélie
authors.initials: A
authors.lastname: Reynaud
authors.affiliation: Service de Cardiologie, CHU Rennes, Rennes, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Thebault
authors.affiliation: INSERM, U1099, Rennes, France; CIC-IT U 804, CHU Rennes, Université Rennes 1, Rennes, France; Service de Cardiologie, CHU Rennes, Rennes, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Mabo
authors.affiliation: INSERM, U1099, Rennes, France; CIC-IT U 804, CHU Rennes, Université Rennes 1, Rennes, France; Service de Cardiologie, CHU Rennes, Rennes, France.
authors.forename: J-Claude
authors.initials: JC
authors.lastname: Daubert
authors.affiliation: Université de Rennes 1, LTSI, Rennes, France; INSERM, U1099, Rennes, France.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Hernandez
mesh_terms: D000368:Aged; D000465:Algorithms; D017147:Defibrillators, Implantable; D004452:Echocardiography / Q000379:methods*; D055119:Elastic Modulus; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013318:Stroke Volume; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000517:prevention & control*
keywords: Cardiac resynchronization therapy; Heart failure; Speckle-tracking echocardiography