title: Local electrogram delay recorded from left ventricular lead at implant predicts response to cardiac resynchronization therapy: retrospective study with 1 year follow up.
abstract: BACKGROUND
  Considerable proportion of patients does not respond to the cardiac resynchronization therapy (CRT). This study investigated clinical relevance of left ventricular electrode local electrogram delay from the beginning of QRS (QLV). We hypothesized that longer QLV indicating more optimal lead placement in the late activated regions is associated with the higher probability of positive CRT response.
  
  
  METHODS
  We conducted a retrospective, single-centre analysis of 161 consecutive patients with heart failure and LBBB or nonspecific intraventricular conduction delay (IVCD) treated with CRT. We routinely intend to implant the LV lead in a region with long QLV. Clinical response to CRT, left ventricular (LV) reverse remodelling (i.e. decrease in LV end-systolic diameter - LVESD ≥10%) and reduction in plasma level of NT-proBNP >30% at 12-month post-implant were the study endpoints. We analyzed association between pre-implant variables and the study endpoints.
  
  
  RESULTS
  Clinical CRT response rate reached 58%, 84% and 92% in the lowest (≤105 ms), middle (106-130 ms) and the highest (>130 ms) QLV tertile (p < 0.0001), respectively. Longer QRS duration (p = 0.002), smaller LVESD and a non-ischemic cardiomyopathy (both p = 0.02) were also univariately associated with positive clinical CRT response. In a multivariate analysis, QLV remained the strongest predictor of clinical CRT response (p < 0.00001), followed by LVESD (p = 0.01) and etiology of LV dysfunction (p = 0.04). Comparable predictive power of QLV for LV reverse remodelling and NT-proBNP response rates was observed.
  
  
  CONCLUSIONS
  LV lead position assessed by duration of the QLV interval was found the strongest independent predictor of beneficial clinical response to CRT.
authors.affiliation: Department of Cardiology, Regional Hospital Liberec, Liberec, Czech Republic. rospo@volny.cz
authors.forename: Rostislav
authors.initials: R
authors.lastname: Polasek
authors.forename: Pavel
authors.initials: P
authors.lastname: Kucera
authors.forename: Pavel
authors.initials: P
authors.lastname: Nedbal
authors.forename: Tomas
authors.initials: T
authors.lastname: Roubicek
authors.forename: Tomas
authors.initials: T
authors.lastname: Belza
authors.forename: Jana
authors.initials: J
authors.lastname: Hanuliakova
authors.forename: David
authors.initials: D
authors.lastname: Horak
authors.forename: Dan
authors.initials: D
authors.lastname: Wichterle
authors.forename: Josef
authors.initials: J
authors.lastname: Kautzner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002037:Bundle-Branch Block / Q000503:physiopathology / Q000628:therapy; D058406:Cardiac Resynchronization Therapy / Q000009:adverse effects; D058409:Cardiac Resynchronization Therapy Devices; D016009:Chi-Square Distribution; D018153:Czech Republic; D022062:Electrophysiologic Techniques, Cardiac; D004867:Equipment Design; D005260:Female; D006327:Heart Block / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D006333:Heart Failure / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D020097:Natriuretic Peptide, Brain / Q000097:blood; D010446:Peptide Fragments / Q000097:blood; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left; D020257:Ventricular Remodeling
chemical_list: D015415:Biomarkers; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain