Etelvino Silva1, Bart Bijnens1, Antonio Berruezo1, Lluis Mont1, Adelina Doltra1, David Andreu1, Josep Brugada1, Marta Sitges2. 1. Servicio de Cardiología, Institut del Tórax, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain. 2. Servicio de Cardiología, Institut del Tórax, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain. Electronic address: msitges@clinic.ub.es.
Abstract
INTRODUCTION AND OBJECTIVES: There is extensive controversy exists on whether cardiac resynchronization therapy corrects electrical or mechanical asynchrony. The aim of this study was to determine if there is a correlation between electrical and mechanical sequences and if myocardial scar has any relevant impact. METHODS: Six patients with normal left ventricular function and 12 patients with left ventricular dysfunction and left bundle branch block, treated with cardiac resynchronization therapy, were studied. Real-time three-dimensional echocardiography and electroanatomical mapping were performed in all patients and, where applicable, before and after therapy. Magnetic resonance was performed for evaluation of myocardial scar. Images were postprocessed and mechanical and electrical activation sequences were defined and time differences between the first and last ventricular segment to be activated were determined. Response to therapy was defined as a reduction in left ventricular end-systolic volume ≥ 15% after 12 months of follow-up. RESULTS: Good correlation between electrical and mechanical timings was found in patients with normal left ventricular function (r(2) = 0.88; P = .005) but not in those with left ventricular dysfunction (r(2) = 0.02; P = not significant). After therapy, both timings and sequences were modified and improved, except in those with myocardial scar. CONCLUSIONS: Despite a close electromechanical relationship in normal left ventricular function, there is no significant correlation in patients with dysfunction. Although resynchronization therapy improves this correlation, the changes in electrical activation may not yield similar changes in left ventricular mechanics particularly depending on the underlying myocardial substrate.
INTRODUCTION AND OBJECTIVES: There is extensive controversy exists on whether cardiac resynchronization therapy corrects electrical or mechanical asynchrony. The aim of this study was to determine if there is a correlation between electrical and mechanical sequences and if myocardial scar has any relevant impact. METHODS: Six patients with normal left ventricular function and 12 patients with left ventricular dysfunction and left bundle branch block, treated with cardiac resynchronization therapy, were studied. Real-time three-dimensional echocardiography and electroanatomical mapping were performed in all patients and, where applicable, before and after therapy. Magnetic resonance was performed for evaluation of myocardial scar. Images were postprocessed and mechanical and electrical activation sequences were defined and time differences between the first and last ventricular segment to be activated were determined. Response to therapy was defined as a reduction in left ventricular end-systolic volume ≥ 15% after 12 months of follow-up. RESULTS: Good correlation between electrical and mechanical timings was found in patients with normal left ventricular function (r(2) = 0.88; P = .005) but not in those with left ventricular dysfunction (r(2) = 0.02; P = not significant). After therapy, both timings and sequences were modified and improved, except in those with myocardial scar. CONCLUSIONS: Despite a close electromechanical relationship in normal left ventricular function, there is no significant correlation in patients with dysfunction. Although resynchronization therapy improves this correlation, the changes in electrical activation may not yield similar changes in left ventricular mechanics particularly depending on the underlying myocardial substrate.
Authors: David Soto Iglesias; Nicolas Duchateau; Constantine Butakoff Kostantyn Butakov; David Andreu; Juan Fernandez-Armenta; Bart Bijnens; Antonio Berruezo; Marta Sitges; Oscar Camara Journal: IEEE J Transl Eng Health Med Date: 2016-12-16 Impact factor: 3.316