title: The effect of left ventricular pacing site on cardiac resynchronization therapy outcome and mortality: the results of a PROSPECT substudy.
abstract: OBJECTIVE
  Left ventricular pacing site (LV-PS) was prospectively collected to test the influence of the anatomical LV-PS on the outcome of cardiac resynchronization therapy (CRT) and mortality.
  
  
  RESULTS
  Four hundred and twenty-six patients with standard indications for CRT underwent echocardiographic and clinical evaluation before and after CRT implantation. The LV-PS was determined from fluoroscopy using the clockwise principle (CP). The LV-PS was categorized into three prospectively defined groups: between 3 and 5 o'clock and longitudinal basal/mid-position (Group A, 'optimal'); between 12 and 2 o'clock and longitudinal mid-apical anterior position (Group B, 'non-optimal'); and all other (Group C, 'other'). Of 333 patients, followed for 0.9 years (mean), adequate images were available to define the LV-PS. Left ventricular pacing site was Group A for 118 patients, Group B for 56, and Group C for 159. The three groups were comparable regarding gender, aetiology, and NYHA class; however, patients in Group A were younger. No relation was found between the LV-PS groups and CRT outcome or all-cause mortality. However, further exploratory subanalyses suggest that LV-PS may impact outcomes in non-ischaemic patients, those with left bundle branch block, and when LV-PS is apical in location.
  
  
  CONCLUSIONS
  Using the CP to define anatomical LV-PS, no relation was found between the LV-PS groups and CRT outcome and mortality. Exploratory analyses warrant further studies.
authors.affiliation: Department of Cardiology B, Aarhus University Hospital, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark. ptm@ki.au.dk
authors.forename: Peter T
authors.initials: PT
authors.lastname: Mortensen
authors.forename: John M
authors.initials: JM
authors.lastname: Herre
authors.forename: Eugene S
authors.initials: ES
authors.lastname: Chung
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: Bax
authors.forename: Bart
authors.initials: B
authors.lastname: Gerritse
authors.forename: Margriet
authors.initials: M
authors.lastname: Kruijshoop
authors.forename: Jaime
authors.initials: J
authors.lastname: Murillo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D058406:Cardiac Resynchronization Therapy; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D005471:Fluoroscopy; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology*; D006333:Heart Failure / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy*; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D015996:Survival Rate; D016896:Treatment Outcome