title: The utility of 12-lead Holter monitoring in patients with permanent atrial fibrillation for the identification of nonresponders after cardiac resynchronization therapy.
abstract: OBJECTIVE
  This study sought to determine the incidence of ineffective capture using 12-lead Holter monitoring and to assess whether this affects response to cardiac resynchronization therapy (CRT).
  
  
  BACKGROUND
  Cardiac resynchronization therapy is used in patients with atrial fibrillation (AF), prolonged QRS duration, and heart failure in the setting of ventricular dysfunction. The percentage of ventricular pacing is used as an indicator of adequate biventricular (BiV) pacing. Although device counters show a high pacing percentage, there may be ineffective capture because of underlying fusion and pseudo-fusion beats.
  
  
  METHODS
  We identified 19 patients (age 72 +/- 8 years, ejection fraction 18 +/- 5%), with permanent AF who underwent CRT. All patients received digoxin, beta-blockers, and amiodarone for rate control; device interrogation showed >90% BiV pacing. Patients had a 12-lead Holter monitor to assess the presence of effective (>90% fully paced beats/24 h) pacing. At 12 months post-CRT, the New York Heart Association functional class was reassessed and an echocardiogram was obtained and compared with pre-CRT.
  
  
  RESULTS
  Only 9 (47%) patients had effective pacing. The other 10 (53%) patients had 16.4 +/- 4.6% fusion and 23.5 +/- 8.7% pseudo-fusion beats. Long-term responders (> or =1 New York Heart Association functional class improvement) to CRT had a significantly higher percentage of fully paced beats (86.4 +/- 17.1% vs. 66.8 +/- 19.1%; p = 0.03) than nonresponders.
  
  
  CONCLUSIONS
  Pacing counters overestimate the degree of effective BiV pacing in patients with permanent AF undergoing CRT therapy. Only patients with complete capture responded clinically to CRT. These findings have important implications for the application of CRT to patients with permanent AF and heart failure.
authors.affiliation: Al-Sabah Arrhythmia Institute and Division of Cardiology, St. Luke's and Roosevelt Hospitals, Columbia University College of Physicians and Surgeons, New York, NY, USA.
authors.forename: Ganesh S
authors.initials: GS
authors.lastname: Kamath
authors.forename: Delia
authors.initials: D
authors.lastname: Cotiga
authors.forename: Jayanthi N
authors.initials: JN
authors.lastname: Koneru
authors.forename: Aysha
authors.initials: A
authors.lastname: Arshad
authors.forename: Walter
authors.initials: W
authors.lastname: Pierce
authors.forename: Emad F
authors.initials: EF
authors.lastname: Aziz
authors.forename: Anisha
authors.initials: A
authors.lastname: Mandava
authors.forename: Suneet
authors.initials: S
authors.lastname: Mittal
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Steinberg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000000981:diagnostic imaging / Q000628:therapy*; D002304:Cardiac Pacing, Artificial; D004452:Echocardiography; D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome