Evidence of reverse electrical remodelling by non-invasive electrocardiographic imaging to assess acute and chronic changes in bulk ventricular activation following cardiac resynchronisation therapy

Cardiac resynchronisation therapy (CRT) corrects electrical dyssynchrony. However, the temporal changes in the electrical timing according to substrate are unclear. We used electrocardiographic imaging (ECGi) for serial non-invasive assessment of the underlying electrical substrate and its response to resynchronisation. ECGi activation maps were constructed 1 day and 6 months post CRT implant. ECGi maps were analysed offline to determine the total ventricular activation time (TVaT) and the time for the bulk of ventricular activation (10th to 90th percentile activation; VaT10–90 Index). Statistical analysis was performed using repeated measures ANOVA with post-hoc pairwise comparisons using paired t-tests. The % relative change within each time point was also calculated and compared between the two time points. Eleven CRT patients were studied. Both total and bulk ventricular activation significantly decreased with CRT turned ON at day 1. Intrinsic (CRT OFF) TVaT and VaT10–90 Index at day 1 were 143 ± 23 and 84 ± 20 ms, respectively, and they significantly decreased post CRT to 115 ± 26 ms (P