title: Cardiac resynchronization therapy in patients with right ventricular pacing-induced cardiomyopathy.
abstract: BACKGROUND
  It is not known whether patients with normal baseline left ventricular (LV) function who develop right ventricular (RV) pacing-induced cardiomyopathy as a result of dual-chamber pacing can benefit from cardiac resynchronization therapy (CRT). We retrospectively assessed the effect of a CRT upgrade on RV pacing-induced cardiomyopathy.
  
  
  RESULTS
  We reviewed the charts of patients who received a CRT device for RV pacing-induced cardiomyopathy. We assessed the effects of CRT on LV function, recovery, and other response parameters. From September 2005 through February 2009, 21 patients (13 men; aged 63 + or - 9 years) underwent a treatment upgrade to a CRT system. Before the dual-chamber pacemaker was implanted, the LV ejection fraction (LVEF) was 53 + or - 2.3%. After pacing, the LVEF was 31.2 + or - 3.8%, the LV end-diastolic dimension (LVEDD) was 5.8 + or - 0.5 cm, and B-type natriuretic peptide (BNP) levels were 426 + or - 149 pg/mL. The duration of pacing before documentation of pacing-induced cardiomyopathy was 3.8 + or - 1.5 months. All the patients had been on a stable medical regimen for at least 2 months. After the upgrade to CRT, the follow-up time was 4.9 + or - 0.9 months. Sixteen patients (76%) reported a significant improvement in their symptoms. After the CRT upgrade, the LVEF increased to 37.4 + or - 9.0% (P < 0.01 vs pre-CRT). The LVEDD decreased to 5.0 + or - 1.0 cm (P = 0.03 vs pre-CRT), and BNP levels decreased to 139 + or - 92 pg/mL (P = 0.08 vs pre-CRT).
  
  
  CONCLUSIONS
  A CRT upgrade is an effective treatment for RV pacing-induced cardiomyopathy and should be implemented as soon as the diagnosis is established. Unfortunately, about 24% of our patients did not respond to the upgrade.
authors.affiliation: Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas, USA.
authors.forename: Alireza
authors.initials: A
authors.lastname: Nazeri
authors.forename: Ali
authors.initials: A
authors.lastname: Massumi
authors.forename: Abdi
authors.initials: A
authors.lastname: Rasekh
authors.forename: Mohammad
authors.initials: M
authors.lastname: Saeed
authors.forename: Christopher
authors.initials: C
authors.lastname: Frank
authors.forename: Mehdi
authors.initials: M
authors.lastname: Razavi
mesh_terms: D002304:Cardiac Pacing, Artificial / Q000009:adverse effects / Q000379:methods*; D009202:Cardiomyopathies / Q000209:etiology* / Q000628:therapy*; D005260:Female; D006352:Heart Ventricles; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies