title: Abnormal Left Ventricular Mechanics of Ventricular Ectopic Beats: Insights Into Origin and Coupling Interval in Premature Ventricular Contraction-Induced Cardiomyopathy.
abstract: BACKGROUND
  Left ventricular (LV) dyssynchrony caused by premature ventricular contractions (PVCs) has been proposed as a mechanism of PVC-induced cardiomyopathy. We sought to understand the impact of different PVC locations and coupling intervals (prematurity) on LV regional mechanics and global function of the PVC beat itself.
  
  
  RESULTS
  Using our premature pacing algorithm, pentageminal PVCs at coupling intervals of 200 to 375 ms were delivered from the epicardial right ventricular apex, RV outflow tract, and LV free wall, as well as premature atrial contractions, from the left atrial appendage at a coupling interval of 200 ms in 7 healthy canines. LV short-axis echocardiographic images, LV stroke volume, and dP/dtmax were obtained during all ectopic beats and ventricular pacing. LV dyssynchrony was assessed by dispersion of QRS-to-peak strain (earliest-last QRS-to-peak strain) between 6 different LV segments during each of the aforementioned beats (GE, EchoPac). LV dyssynchrony was greater during long-coupled rather than short-coupled PVCs and PVCs at 375 ms compared with rapid ventricular pacing at 400 ms (P<0.0001), whereas no difference was found between PVC locations. Longer PVC coupling intervals were associated with greater stroke volume and dP/dtmax despite more pronounced dyssynchrony (P<0.001).
  
  
  CONCLUSIONS
  PVCs with longer coupling intervals demonstrate more pronounced LV dyssynchrony, whereas PVC location has minimal impact. LV dyssynchrony cannot be attributed to prematurity or abnormal ventricular activation alone, but rather to a combination of both. This study suggests that late-coupled PVCs may cause a more severe cardiomyopathy if dyssynchrony is the leading mechanism responsible for PVC-induced cardiomyopathy.
authors: From the Cardiology Division, Hunter Holmes McGuire VA Medical Center, Richmond, VA (J.P., K.K., A.Y.T., J.F.H.); Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond (J.P., K.K., A.Y.T., K.A.E., J.F.H.); School of Biostatistics, Virginia Commonwealth University, Richmond (A.P.S.); and Cardiology Division, University of Pittsburgh Medical Center, PA (J.G. III).
authors: Jonathan
authors: J
authors: Potfay
authors: From the Cardiology Division, Hunter Holmes McGuire VA Medical Center, Richmond, VA (J.P., K.K., A.Y.T., J.F.H.); Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond (J.P., K.K., A.Y.T., K.A.E., J.F.H.); School of Biostatistics, Virginia Commonwealth University, Richmond (A.P.S.); and Cardiology Division, University of Pittsburgh Medical Center, PA (J.G. III).
authors: Karoly
authors: K
authors: Kaszala
authors: From the Cardiology Division, Hunter Holmes McGuire VA Medical Center, Richmond, VA (J.P., K.K., A.Y.T., J.F.H.); Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond (J.P., K.K., A.Y.T., K.A.E., J.F.H.); School of Biostatistics, Virginia Commonwealth University, Richmond (A.P.S.); and Cardiology Division, University of Pittsburgh Medical Center, PA (J.G. III).
authors: Alex Y
authors: AY
authors: Tan
authors: From the Cardiology Division, Hunter Holmes McGuire VA Medical Center, Richmond, VA (J.P., K.K., A.Y.T., J.F.H.); Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond (J.P., K.K., A.Y.T., K.A.E., J.F.H.); School of Biostatistics, Virginia Commonwealth University, Richmond (A.P.S.); and Cardiology Division, University of Pittsburgh Medical Center, PA (J.G. III).
authors: Adam P
authors: AP
authors: Sima
authors: From the Cardiology Division, Hunter Holmes McGuire VA Medical Center, Richmond, VA (J.P., K.K., A.Y.T., J.F.H.); Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond (J.P., K.K., A.Y.T., K.A.E., J.F.H.); School of Biostatistics, Virginia Commonwealth University, Richmond (A.P.S.); and Cardiology Division, University of Pittsburgh Medical Center, PA (J.G. III).
authors: John
authors: J
authors: Gorcsan
authors: From the Cardiology Division, Hunter Holmes McGuire VA Medical Center, Richmond, VA (J.P., K.K., A.Y.T., J.F.H.); Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond (J.P., K.K., A.Y.T., K.A.E., J.F.H.); School of Biostatistics, Virginia Commonwealth University, Richmond (A.P.S.); and Cardiology Division, University of Pittsburgh Medical Center, PA (J.G. III).
authors: Kenneth A
authors: KA
authors: Ellenbogen
authors: From the Cardiology Division, Hunter Holmes McGuire VA Medical Center, Richmond, VA (J.P., K.K., A.Y.T., J.F.H.); Cardiology Division/Pauley Heart Center, Virginia Commonwealth University, Richmond (J.P., K.K., A.Y.T., K.A.E., J.F.H.); School of Biostatistics, Virginia Commonwealth University, Richmond (A.P.S.); and Cardiology Division, University of Pittsburgh Medical Center, PA (J.G. III). jose.huizar2@va.gov.
authors: Jose F
authors: JF
authors: Huizar
mesh_terms: D058606:Accessory Atrioventricular Bundle / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial; D009202:Cardiomyopathies / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D018879:Ventricular Premature Complexes / Q000150:complications* / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy
keywords: cardiomyopathies; heart ventricles; stroke volume; ventricular dysfunction, left; ventricular premature contraction