title: Prognostic Impact of QRS Axis Deviation in Patients Treated With Cardiac Resynchronization Therapy.
abstract: BACKGROUND
  QRS duration and morphology are currently recognized as recommended criteria for the selection of CRT candidates. It has recently been shown that patients with left bundle branch block (LBBB) derive substantial clinical benefit from CRT. The aim of this study is to investigate the prognostic impact of QRS axis deviation (AD) in HF patients with LBBB undergoing CRT.
  
  
  RESULTS
  We retrospectively evaluated 707 HF patients with LBBB who underwent CRT at five centers. Baseline QRS axis was defined as normal (NA: -30° to 90°), right axis deviation (RAD: 90° to 180°) and left axis deviation (LAD: <-30°). The primary endpoint was a composite of all cause death/HF hospitalization. The risk of endpoint by AD was evaluated with both Kaplan-Meier and Cox proportional hazard analysis. Among 707 patients (73% M, median age: 71 [62,77] years), 323 (46%) had NA, 359 (51%) LAD, and 25 (3.5%) RAD. Baseline clinical characteristics were similar between the three groups. Over a mean follow-up of 32 ± 25 months, 141 deaths occurred (21%) and 36% (n = 255) met with the composite endpoint. A significantly higher proportion of RAD patients (52%) reached the endpoint (LAD 40%, NA 30%). KM analysis showed that RAD and LAD patients had worse event free survival and in multivariate analysis both LAD (HR: 1.40; 95% CI: 1.05-1.86; P = 0.021) and RAD (HR: 2.49; 95% CI: 1.31-4.74; P = 0.005) were independently associated with worse clinical outcome.
  
  
  CONCLUSIONS
  Right or left axis deviation in the presence of LBBB in HF patients undergoing CRT are independent predictors of poor prognosis.
authors.affiliation: University of Florence, Florence, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Perrotta
authors.affiliation: Division of Cardiology, Massachusetts General Hospital, Harvard Medical School, Boston, USA.
authors.forename: Jagdesh
authors.initials: J
authors.lastname: Kandala
authors.affiliation: Texas Cardiac Arrhythmia Institute, Austin, USA.
authors.forename: Luigi
authors.initials: L
authors.lastname: DI Biase
authors.affiliation: Fondazione Monasterio, Pisa, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Valleggi
authors.affiliation: University of Florence, Florence, Italy.|Gavazzeni Hospital, Bergamo, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Michelotti
authors.affiliation: University of Florence, Florence, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Pieragnoli
authors.affiliation: University of Florence, Florence, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ricciardi
authors.affiliation: Gavazzeni Hospital, Bergamo, Italy.
authors.forename: Giosuè
authors.initials: G
authors.lastname: Mascioli
authors.affiliation: Bloch Heart Rhythm Center, Division of Cardiovascular Diseases, Cardiovascular Research Institute, University of Kansas Hospital & Medical Center, Kansas City, Kansas, USA.
authors.forename: Dhanunjaya
authors.initials: D
authors.lastname: Lakkireddy
authors.affiliation: Bloch Heart Rhythm Center, Division of Cardiovascular Diseases, Cardiovascular Research Institute, University of Kansas Hospital & Medical Center, Kansas City, Kansas, USA.
authors.forename: Jayasree
authors.initials: J
authors.lastname: Pillarisetti
authors.affiliation: Fondazione Monasterio, Pisa, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Emdin
authors.affiliation: Texas Cardiac Arrhythmia Institute, Austin, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Natale
authors.affiliation: Division of Cardiology, Massachusetts General Hospital, Harvard Medical School, Boston, USA.
authors.forename: Jagmeet P
authors.initials: JP
authors.lastname: Singh
authors.affiliation: University of Florence, Florence, Italy.|IRCCS MultiMedica, Milano, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Padeletti
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology*; D006333:Heart Failure / Q000175:diagnosis* / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: QRS axis deviation; cardiac resynchronization therapy; heart failure; left bundle branch block