title: Acute echocardiographic optimization of multiple stimulation configurations of cardiac resynchronization therapy through quadripolar left ventricular pacing: a tailored approach.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) is ineffective in approximately 30% of recipients, in part due to sub-optimal left ventricular (LV) pacing location. The Quartet LV lead, with 2 additional electrodes proximal to conventional bipolar lead electrodes, enables 10 different pacing configurations at four independent LV locations. In a CRT patient cohort, we sought to evaluate the spectrum of echocardiographic and electrocardiographic response over these 10 configurations, to select the optimal one in each patient. Moreover, we sought to evaluate the 6-months clinical and echocardiographic response to a "tailored approach" in which the optimal LV pacing configuration for CRT was determined by echocardiographic measures, QRSd and pacing capture thresholds.
  
  
  METHODS
  Twenty-two consecutive CRT indicated patients were implanted with a quadripolar CRT system (St. Jude Medical). Optimal LV pacing configuration was determined by echocardiographic measures, including velocity time integral (VTI), myocardial performance index (MPI) and mitral regurgitation (MR), and an electrocardiographic measure (QRS duration) during pacing from each of the configurations at pre-discharge. The optimal LV pacing vector was chosen for every patient. Clinical and echocardiographic assessment was repeated after 6 months.
  
  
  RESULTS
  Various configurations provided different VTI, MPI, MR and QRSd values. Conventional bipolar vectors (ie, D1-M2, D1-RVc, M2-RVc) were rarely associated with the best echocardiographic improvements and provided significantly worse VTI, MR, MPI, and QRSd values than the best configuration for every patient (P = .005, P = .05 and P = .03 for VTI; P = .01, P = .005 and P = .001 for MPI; P = .003, P = .01 and P = .005 for MR, P > .5, P = .01 and P = .05 for QRSd) Conversely, "unconventional" proximal configurations (ie, making use of P4 and M3 electrodes) were generally characterized by higher acute VTI, MR and MPI improvements. CRT devices were reprogrammed with an "unconventional" LV pacing configuration in 50% of patients. A significant improvement in New York Heart Association class (81%), LV ejection fraction (76%), end-diastolic and end-systolic volumes was observed after 6 months (P = .02, P < .001, P = .02 and P = .003, respectively).
  
  
  CONCLUSIONS
  In this study, conventional bipolar vectors of quadripolar-CRT were rarely associated with the best echocardiographic improvements. Quadripolar CRT utilizing optimal LV pacing configuration was associated with a significant improvement in New York Heart Association class and LV ejection fraction after 6 months.
authors.affiliation: Division of Cardiology, Policlinico Casilino, ASL Rome B, Rome, Italy. Electronic address: leonardo.calo@tin.it.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Calò
authors.affiliation: Division of Cardiology, Policlinico Casilino, ASL Rome B, Rome, Italy.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Martino
authors.affiliation: Division of Cardiology, Policlinico Casilino, ASL Rome B, Rome, Italy.
authors.forename: Ermenegildo
authors.initials: E
authors.lastname: de Ruvo
authors.affiliation: Division of Cardiology, Policlinico Casilino, ASL Rome B, Rome, Italy.
authors.forename: Monia
authors.initials: M
authors.lastname: Minati
authors.affiliation: Division of Cardiology, Policlinico Casilino, ASL Rome B, Rome, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Fratini
authors.affiliation: Division of Cardiology, Policlinico Casilino, ASL Rome B, Rome, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Rebecchi
authors.affiliation: Division of Cardiology, Policlinico Casilino, ASL Rome B, Rome, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Lanzillo
authors.affiliation: Division of Cardiology, Policlinico Casilino, ASL Rome B, Rome, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Fagagnini
authors.affiliation: Division of Cardiology, Policlinico Casilino, ASL Rome B, Rome, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Borrelli
authors.affiliation: Division of Cardiology, Policlinico Casilino, ASL Rome B, Rome, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: De Luca
authors.affiliation: Division of Cardiology, Policlinico Casilino, ASL Rome B, Rome, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Sciarra
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000592:standards*; D004452:Echocardiography / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D011446:Prospective Studies; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology*