title: Comparison of left ventricular torsion and strain with biventricular pacing in patients with underlying right bundle branch block versus those with left bundle branch block.
abstract: The benefits of biventricular pacing in patients with cardiac resynchronization therapy (CRT) remain poorly understood in those with right bundle branch block (RBBB). The aim of this study was to examine the differences in several speckle tracking-derived parameters, including left ventricular torsion and longitudinal strain with CRT on and off for patients with underlying left bundle branch block (LBBB) and RBBB. Twelve patients with CRT and RBBB were compared with a similar group of patients with underlying LBBB who were sent for evaluation and atrioventricular optimization. Echocardiographic images were acquired with biventricular pacing on and off. The 2 groups had similar baseline characteristics, including age, the ejection fraction, and QRS duration. During intrinsic conduction (CRT off), patients with LBBB had lower torsion angles than those with RBBB (2.3 ± 1.0° in those with LBBB vs 6.3 ± 1.0° in those with RBBB, p = 0.03) but trended toward improvements in torsional parameters, including torsional angle and peak untwisting velocity with CRT on, whereas these parameters worsened in patients with RBBB. Compared with CRT off, analyses of septal and lateral strain curves showed significant improvements in septal strain during 100% and 200% of systole with CRT on in patients with LBBB, whereas biventricular pacing resulted in a trend toward worsening of septal strain in patients with RBBB. Negligible changes were noted in lateral strain values. In conclusion, CRT favorably improves regional mechanics in patients with LBBB primarily involving the ventricular septum, with a negligible positive impact on cardiac function in patients with underlying RBBB.
authors.affiliation: Division of Cardiology, Department of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Sabe
authors.initials: S
authors.lastname: De
authors.affiliation: Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Zoran B
authors.initials: ZB
authors.lastname: Popović
authors.affiliation: Department of Cardiovascular Medicine, Ziekenhuis Oost-Limburg, Genk, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: Verhaert
authors.affiliation: Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dresing
authors.affiliation: Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Bruce
authors.initials: B
authors.lastname: Wilkoff
authors.affiliation: Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Randall
authors.initials: R
authors.lastname: Starling
authors.affiliation: Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: W H Wilson
authors.initials: WH
authors.lastname: Tang
authors.affiliation: Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: James D
authors.initials: JD
authors.lastname: Thomas
authors.affiliation: Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio. Electronic address: grimmr@ccf.org.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Grimm
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D018619:Echocardiography, Doppler, Pulsed; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology*; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013318:Stroke Volume; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology*