In vivo electromechanical assessment of heart failure patients with prolonged QRS duration.
BACKGROUND
Combined measurement of electrical activation and mechanical dyssynchrony in heart failure (HF) patients is scarce but may contain important mechanistic and diagnostic clues.


OBJECTIVE
The purpose of this study was to characterize the electromechanical (EM) coupling in HF patients with prolonged QRS duration.


METHODS
Ten patients with QRS width >120 ms underwent left ventricular (LV) electroanatomic contact mapping using the Noga® XP system (Biosense Webster). Recorded voltages during the cardiac cycle were converted to maps of depolarization time (TD). Electrode positions were tracked and converted into maps of time-to-peak shortening (TPS) using custom-made deformation analysis software. Correlation analysis was performed between the 2 maps to quantify EM coupling. Simulations with the CircAdapt cardiovascular system model were performed to mechanistically unravel the observed relation between TD and TPS.


RESULTS
The delay between earliest LV electrical activation and peak shortening differed considerably between patients (TPSmin-TDmin = 360 ± 73 ms). On average, total mechanical dyssynchrony exceeded total electrical activation (ΔTPS = 177 ± 47 ms vs ΔTD = 93 ± 24 ms, P <.001), but a large interpatient variability was observed. The TD and TPS maps correlated strongly in all patients (median R = 0.87, P <.001). These correlations were similar for regions with unipolar voltages above and below 6mV (Mann-Whitney U test, P = .93). Computer simulations revealed that increased passive myocardial stiffness decreases ΔTPS relative to ΔTD and that lower contractility predominantly increases TPSmin-TDmin.


CONCLUSIONS
EM coupling in HF patients is maintained, but the relationship between TD and TPS differs strongly between patients. Intra-individual and inter-individual differences may be explained by local and global differences in passive and contractile myocardial properties.
Center for Computational Medicine in Cardiology, Institute of Computational Science, University of Lugano, Lugano, Switzerland.
Wilco
W
Kroon
Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.
Joost
J
Lumens
Center for Computational Medicine in Cardiology, Institute of Computational Science, University of Lugano, Lugano, Switzerland.
Mark
M
Potse
Division of Cardiology, Fondazione Cardiocentro Ticino, Lugano, Switzerland.
Daniel
D
Suerder
Service of Biometry & Statistics, IRCCS Fondazione Policlinico San Matteo, Pavia, Italy.
Catherine
C
Klersy
Division of Cardiology, Fondazione Cardiocentro Ticino, Lugano, Switzerland.
Francois
F
Regoli
Division of Cardiology, Fondazione Cardiocentro Ticino, Lugano, Switzerland.
Romina
R
Murzilli
Division of Cardiology, Fondazione Cardiocentro Ticino, Lugano, Switzerland.
Tiziano
T
Moccetti
Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.
Tammo
T
Delhaas
Center for Computational Medicine in Cardiology, Institute of Computational Science, University of Lugano, Lugano, Switzerland.
Rolf
R
Krause
Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.
Frits W
FW
Prinzen
Center for Computational Medicine in Cardiology, Institute of Computational Science, University of Lugano, Lugano, Switzerland; Division of Cardiology, Fondazione Cardiocentro Ticino, Lugano, Switzerland. Electronic address: angelo.auricchio@cardiocentro.org.
Angelo
A
Auricchio
D000368:Aged; D003198:Computer Simulation; D004562:Electrocardiography; D006333:Heart Failure / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D009200:Myocardial Contraction / Q000502:physiology
Cardiac resynchronization therapy; Electromechanical delay; Excitation–contraction coupling; Heart failure; Left bundle branch block; Mapping; QRS duration