title: Interlead distance and left ventricular lead electrical delay predict reverse remodeling during cardiac resynchronization therapy.
abstract: BACKGROUND
  Both anatomic interlead separation and left ventricle lead electrical delay (LVLED) have been associated with outcomes following cardiac resynchronization therapy (CRT). However, the relationship between interlead distance and electrical delay in predicting CRT outcomes has not been defined.
  
  
  METHODS
  We studied 61 consecutive patients undergoing CRT for standard clinical indications. All patients underwent intraprocedural measurement of LVLED. Interlead distances in the horizontal (HD), vertical (VD), and direct (DD) dimensions were measured from postprocedure chest radiographs (CXR). Remodeling indices [percent change in left ventricle (LV) ejection fraction, end-diastolic, end-systolic dimensions] were assessed by transthoracic echocardiogram.
  
  
  RESULTS
  There was a positive correlation between corrected LVLED and HD on lateral CXR (r = 0.361, P = 0.004) and a negative correlation between LVLED and VD on posteroanterior (PA) CXR (r =-0.281, P = 0.028). To account for this inverse relationship, we developed a composite anatomic distance (defined as: lateral HD-PA VD), which correlated most closely with LVLED (r = 0.404, P = 0.001). Follow-up was available for 48 patients. At a mean of 4.1 +/- 3.2 months, patients with optimal values for both corrected LVLED (>or=75%) and composite anatomic distance (>or=15 cm) demonstrated greater reverse LV remodeling than patients with either one or neither of these optimized values.
  
  
  CONCLUSIONS
  We identified a significant correlation between LV-right ventricular interlead distance and LVLED; additionally, both parameters act synergistically in predicting LV anatomic reverse remodeling. Efforts to optimize both interlead distance and electrical delay may improve CRT outcomes.
authors.affiliation: Cardiology Division, Massachusetts General Hospital Heart Center, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Faisal M
authors.initials: FM
authors.lastname: Merchant
authors.forename: E Kevin
authors.initials: EK
authors.lastname: Heist
authors.forename: K Veena
authors.initials: KV
authors.lastname: Nandigam
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Mulligan
authors.forename: Dan
authors.initials: D
authors.lastname: Blendea
authors.forename: Lindsay
authors.initials: L
authors.lastname: Riedl
authors.forename: David
authors.initials: D
authors.lastname: McCarty
authors.forename: Mary
authors.initials: M
authors.lastname: Orencole
authors.forename: Michael H
authors.initials: MH
authors.lastname: Picard
authors.forename: Jeremy N
authors.initials: JN
authors.lastname: Ruskin
authors.forename: Jagmeet P
authors.initials: JP
authors.lastname: Singh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002304:Cardiac Pacing, Artificial / Q000379:methods; D004567:Electrodes, Implanted; D005260:Female; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy*; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D011446:Prospective Studies; D013318:Stroke Volume / Q000502:physiology; D016896:Treatment Outcome; D014463:Ultrasonography; D020257:Ventricular Remodeling / Q000502:physiology*