title: Electrocardiographic patterns and long-term clinical outcome in cardiac resynchronization therapy.
abstract: OBJECTIVE
  The present study aims to identify the predictive value of electrocardiographic (ECG) patterns on long-term clinical and echocardiographic outcome in patients treated with cardiac resynchronization therapy (CRT).
  
  
  RESULTS
  Clinical information including a standard 12-lead ECG was collected from patient files in consecutive patients treated with CRT from 1997 to 2007. Symptomatic response was defined as improvement in New York Heart Association class (> or =1) and echocardiographic response as improvement in left ventricular ejection fraction of > or =5% absolute. We included 659 patients [median age 66 years, 526 (80%) male]. There was a higher all-cause and cardiac mortality in patients with left bundle branch block (LBBB), prolonged PR interval, right-axis deviation combined with LBBB in the pre-implant ECG, and no QRS reduction after CRT. Patients with right bundle branch block and patients with an intermediate QRS duration (150-200 ms) had a higher chance of symptomatic improvement, and patients with normal PR interval and normal axis in LBBB had a higher chance of echocardiographic improvement.
  
  
  CONCLUSIONS
  Cardiac resynchronization therapy does not change the predictive value of ECG patterns in heart failure patients with bundle branch block, where LBBB, a prolonged PR, and an abnormal axis in LBBB are signs of a more severe degree of myocardial disease, and therefore a worse outcome. Lack of electrical resynchronization defined as an unchanged or prolonged QRS duration is associated with higher all-cause and cardiac mortality in patients treated with CRT.
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Skejby, Bendstrupgaardsvej 100, DK-8200 Aarhus N, Denmark. mads.brix.kronborg@ki.au.dk
authors.forename: Mads B
authors.initials: MB
authors.lastname: Kronborg
authors.forename: Jens C
authors.initials: JC
authors.lastname: Nielsen
authors.forename: Peter T
authors.initials: PT
authors.lastname: Mortensen
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D017147:Defibrillators, Implantable; D003718:Denmark; D004562:Electrocardiography; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D016896:Treatment Outcome