title: An electrocardiogram-based algorithm to detect loss of left ventricular capture during cardiac resynchronization therapy.
abstract: BACKGROUND
  Loss of left ventricular capture in patients with cardiac resynchronization devices may account for worsening heart failure and can be difficult to diagnose without a programmer.
  
  
  OBJECTIVE
  To determine whether distinct morphologic changes on the surface electrocardiogram indicate loss of left ventricular capture.
  
  
  METHODS
  After analysis of the R-S spike ratio in the 12-lead electrocardiogram during right ventricular and biventricular pacing in 10 patients, an algorithm to detect loss of left ventricular capture was developed.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  54 patients with a cardiac resynchronization device and underlying left bundle-branch block.
  
  
  METHODS
  Leads V1 and I of a 12-lead electrocardiogram were assessed after biventricular pacing was confirmed and after the device was programmed to right ventricular pacing only (simulating loss of left ventricular capture).
  
  
  RESULTS
  The sensitivity of the algorithm to correctly identify loss of left ventricular capture was 94% (95% CI, 88.2% to 97.7%), and the specificity was 93% (CI, 86.3% to 95.8%). The likelihood ratio of a positive test result was 12.8 (CI, 6.443 to 23.310), and the likelihood ratio of a negative test result was 0.06 (CI, 0.024 to 0.137).
  
  
  CONCLUSIONS
  The algorithm was tested in patients in whom the right ventricular electrode was placed in the apex of the right ventricle only.
  
  
  CONCLUSIONS
  Presence of biventricular capture--the prerequisite for successful cardiac resynchronization therapy--and loss of left ventricular capture can be accurately detected by an algorithm based on analysis of the R-S ratio on leads V1 and I of the surface electrocardiogram.
authors.affiliation: University Hospital, Basel, Switzerland. peter.ammann@kssg.ch
authors.forename: Peter
authors.initials: P
authors.lastname: Ammann
authors.forename: Christian
authors.initials: C
authors.lastname: Sticherling
authors.forename: Dietrich
authors.initials: D
authors.lastname: Kalusche
authors.forename: Jens
authors.initials: J
authors.lastname: Eckstein
authors.forename: Alain
authors.initials: A
authors.lastname: Bernheim
authors.forename: Beat
authors.initials: B
authors.lastname: Schaer
authors.forename: Stefan
authors.initials: S
authors.lastname: Osswald
mesh_terms: D000465:Algorithms; D002037:Bundle-Branch Block / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography / Q000379:methods*; D006333:Heart Failure / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D012680:Sensitivity and Specificity; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000503:physiopathology