title: Impact of ventricular ectopic burden in a premature ventricular contraction-induced cardiomyopathy animal model.
abstract: BACKGROUND
  Frequent premature ventricular contractions (PVCs) have been associated with PVC-induced cardiomyopathy (CM) in some patients.
  
  
  OBJECTIVE
  The purpose of this study was to understand the cardiac consequences of different PVC burdens and the minimum burden required to induce left ventricular (LV) dysfunction.
  
  
  METHODS
  Right ventricular apical PVCs at a coupling interval of 240 ms were introduced at different PVC burdens in 9 mongrel canines. A stepwise increase in PVC burden was implemented every 8 weeks from 0% (baseline), 7%, 14%, 25%, 33% to 50% using our premature pacing algorithm. Echocardiogram and 24-hour Holter were obtained at 4- and 8-week period for each PVC burden with a single blinded reader assessing all echocardiographic parameters including those assessed by speckle tracking imaging (EchoPAC workstation, General Electric). CM was defined as left ventricular ejection fraction (LVEF) <50% or LVEF drop >10% points. Interleukin-6 and pro-brain natriuretic peptide levels were obtained at the end of each PVC burden.
  
  
  RESULTS
  The mean LVEF (mean heart rate) at 8 weeks for each PVC burden (0%, 7%, 14%, 33%, and 50%) were 57% ± 2.9% (85 ± 13 beats/min), 54.4% ± 3% (81 ± 10 beats/min), 53.3% ± 5% (77 ± 12 beats/min), 51.1% ± 4.2% (79 ± 14 beats/min), 47.7% ± 3.8% (80 ± 14 beats/min), and 44.7% ± 1.9% (157 ± 43 beats/min). PVC-induced CM was present in 11.1%, 44.4%, and 100% of animals with 25%, 33%, and 50% PVC burden, respectively. E/A ratio and radial strain decreased while left atrial size increased beyond 33% PVC burden. No changes in pro-brain natriuretic peptide and interleukin-6 levels were noted at any PVC burden.
  
  
  CONCLUSIONS
  LV systolic function (LVEF and radial strain) declined linearly as PVC burden increased. PVC-induced CM developed in some canines with 25% and 33% PVC burden, but developed in all animals with 50% PVC burden.
authors.affiliation: Cardiology Division, Hunter Holmes McGuire VA Medical Center, Richmond, Virginia; Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Alex Y
authors.initials: AY
authors.lastname: Tan
authors.affiliation: Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Yuhning L
authors.initials: YL
authors.lastname: Hu
authors.affiliation: Cardiology Division, Hunter Holmes McGuire VA Medical Center, Richmond, Virginia; Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Potfay
authors.affiliation: Cardiology Division, Hunter Holmes McGuire VA Medical Center, Richmond, Virginia; Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Karoly
authors.initials: K
authors.lastname: Kaszala
authors.affiliation: Cardiology Division, Hunter Holmes McGuire VA Medical Center, Richmond, Virginia.
authors.forename: Maureen
authors.initials: M
authors.lastname: Howren
authors.affiliation: Department of Biostatistics, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Sima
authors.affiliation: Cardiology Division, Hunter Holmes McGuire VA Medical Center, Richmond, Virginia.
authors.forename: Michael
authors.initials: M
authors.lastname: Shultz
authors.affiliation: Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Jayanthi N
authors.initials: JN
authors.lastname: Koneru
authors.affiliation: Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Ellenbogen
authors.affiliation: Cardiology Division, Hunter Holmes McGuire VA Medical Center, Richmond, Virginia; Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond, Virginia. Electronic address: jfhuizar@gmail.com.
authors.forename: Jose F
authors.initials: JF
authors.lastname: Huizar
mesh_terms: D000818:Animals; D009202:Cardiomyopathies / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D004195:Disease Models, Animal; D004285:Dogs; D004452:Echocardiography; D004562:Electrocardiography; D013318:Stroke Volume / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology*; D018879:Ventricular Premature Complexes / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology
keywords: Cardiomyopathy; LV dysfunction; PVC-induced cardiomyopathy; Premature ventricular contractions