title: P-wave morphology is associated with echocardiographic response to cardiac resynchronization therapy in MADIT-CRT patients.
abstract: BACKGROUND
  In this study we hypothesized that signs of atypical atrial activation would be associated with cardiac resynchronization therapy (CRT) response in patients with mildly symptomatic heart failure (CHF), left ventricular dysfunction, and wide QRS complex.
  
  
  METHODS
  Patients included in the CRT-D arm in MADIT-CRT were studied (n = 892). Unfiltered signal-averaged P waves were analyzed to determine orthogonal P-wave morphology (typical morphologies were predefined as having positive signals in Leads X and Y and a negative or negative-positive signal in Lead Z. All other patterns were classified as atypical). The association between P-wave morphology and data on echocardiographic response at 1 year was analyzed.
  
  
  RESULTS
  Atypical P-wave morphology was found in 21% (n = 186) of the patients at baseline. Patients with atypical P-wave morphology were more often female (31% vs. 24%, P = 0.025), had lower BMI (28 ± 5 kg/m(2) vs. 29 ± 5 kg/m(2) , P = 0.008), had more ischemic CHF (60% vs. 52%, P = 0.026) and had smaller left atrial volumes (90 ± 20 mL vs. 94 ± 22 mL, P = 0.034). Atypical P-wave morphology at baseline was associated with superior response to CRT at 1 year with a larger reduction in left ventricular end-diastolic volume (-23 ± 12% vs. -20 ± 11%, P = 0.009), left ventricular end-systolic volume (-36 ± 16% vs. -31 ± 16%, P = 0.006), and left atrial volume (-31 ± 12% vs. -27 ± 12%, P = 0.005), with a slightly larger absolute increase in left ventricular ejection fraction (LVEF) (12 ± 5% vs. 11 ± 5%, P = 0.009). These associations were found to be independent of traditional predictors.
  
  
  CONCLUSIONS
  The presence of atypical P-wave morphology recorded is independently associated with a favorable echocardiographic cardiac remodeling response to CRT.
authors.affiliation: Department of Cardiology, Lund University, Lund, Sweden; Center for Integrative Electrocardiology, Lund University, Lund, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Holmqvist
authors.forename: Pyotr G
authors.initials: PG
authors.lastname: Platonov
authors.forename: Scott D
authors.initials: SD
authors.lastname: Solomon
authors.forename: Richard
authors.initials: R
authors.lastname: Petersson
authors.forename: Scott
authors.initials: S
authors.lastname: McNitt
authors.forename: Jonas
authors.initials: J
authors.lastname: Carlson
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Moss
mesh_terms: D000704:Analysis of Variance; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D017147:Defibrillators, Implantable; D004562:Electrocardiography / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000503:physiopathology; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy*; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D017678:Sex Distribution; D016896:Treatment Outcome; D014463:Ultrasonography; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy*
keywords: CRT; ECG; atrial electrophysiology; congestive heart failure; echocardiography; responders