title: Dilated cardiomyopathy following right ventricular pacing for AV block in young patients: resolution after upgrading to biventricular pacing systems.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) has been demonstrated to result in clinical improvement in older adult patients with dilated cardiomyopathy (DCM), specifically those with left bundle branch block and prolonged QRS duration. We sought to demonstrate the benefits of CRT on improvement in cardiac function and clinical outcome in young patients that developed congestive heart failure (CHF) and DCM following cardiac pacing for AV block.
  
  
  RESULTS
  We reviewed the charts of six patients who developed CHF or low cardiac output symptoms and DCM following implantation of right ventricular (RV)-based pacing systems for AV block, and subsequently underwent CRT. Patients ranged in age from 6 months to 23.7 years (mean: 11.3 +/- 3.6 years). AV block was congenital (3), post-surgery (2), and acquired (1). Pacing had been performed for 0.1-14.5 (7.6 +/- 2.4) years prior to development of DCM. Two patients required listing for cardiac transplantation. Following CRT: (1) QRS duration shortened from 204 +/- 15 to 138 +/- 10 msec, P = 0.002, (2) left ventricular ejection fraction improved from 34 +/- 6 to 60 +/- 2%, P = 0.003, and (3) left ventricular end diastolic dimension shortened from 5.5 +/- 0.8 to 4.3 +/- 0.5 cm, P = 0.03. All patients demonstrated clinical improvement and have been weaned from CHF medications and listing for cardiac transplantation.
  
  
  CONCLUSIONS
  CRT can benefit young patients that develop CHF and DCM following RV pacing for AV block. Upgrading to biventricular pacing systems should be considered early in the management of these patients prior to listing for cardiac transplantation.
authors.affiliation: Department of Cardiology, Children's National Medical Center, Washington, DC 20010, USA. jmoak@cnmc.org
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Moak
authors.forename: Keren
authors.initials: K
authors.lastname: Hasbani
authors.forename: Carolyn
authors.initials: C
authors.lastname: Ramwell
authors.forename: Vicki
authors.initials: V
authors.lastname: Freedenberg
authors.forename: John T
authors.initials: JT
authors.lastname: Berger
authors.forename: Gregory
authors.initials: G
authors.lastname: DiRusso
authors.forename: Patrick
authors.initials: P
authors.lastname: Callahan
mesh_terms: D000293:Adolescent; D000328:Adult; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects* / Q000379:methods*; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000628:therapy*; D002648:Child; D005260:Female; D006327:Heart Block / Q000150:complications / Q000628:therapy; D006333:Heart Failure / Q000209:etiology* / Q000517:prevention & control*; D006352:Heart Ventricles / Q000294:innervation; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D016896:Treatment Outcome