Adaptive CRT algorithm and electrical synchrony

Abstract

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): United Hospital Medical Education and Research Committee, United Hospital Foundation. Background We have previously shown that optimization of cardiac resynchronization therapy (CRT) nonresponders using a novel electrical dyssynchrony mapping (EDM) system significantly improves electrical dyssynchrony, left ventricle (LV) size and systolic function. Whether this methodology can improve electrical dyssynchrony (and potentially LV function) in nonresponder patients programmed with the adaptive CRT (aCRT) algorithm is not known. Purpose To quantify electrical dyssynchrony in CRT nonresponders programmed using aCRT and determine if it can be improved using EDM. Methods We studied 97 patients programmed with the aCRT algorithm at multiple device settings with an ECG system of 9 anterior and 9 posterior electrodes. We quantified electrical dyssynchrony using a measure of wavefront fusion, cardiac resynchronization index (CRI), calculated as % change in area under the curve between all combinations of anterior and posterior electrodes as compared to native LBBB (CRT off). CRI results were displayed on an electrical dyssynchrony map (EDM) showing atrial-to-right ventricle-paced intervals (A-RVp) on the y-axis and atrial-to-left ventricle-paced intervals (A-LVp) on the x-axis. Results Figure 1 shows an EDM for a typical patient with CRI values marked at different programmed settings. Figure 2 shows CRI for 58 patients programmed LV-only by aCRT at baseline (red bars) and 39 patients programmed biventricular (BiV) by aCRT at baseline (blue bars). CRI at baseline was significantly (p≤0.001) higher in patients programmed LV-only vs. those programmed BiV. In both groups programming to LV-only at the optimal atrial-ventricular delay (AVD) and to sequential BiV pacing at the optimal ventricular-ventricular delay (VVD) produced significantly and markedly better CRI as compared to CRI at aCRT baseline settings. In the patients programmed by aCRT at baseline to LV-only, BiV VV=0 at standard device setting (SAV 120 ms) had significantly worse CRI than baseline. Conclusions Electrical dyssynchrony as measured by CRI is better in patients programmed aCRT LV-only than those programmed aCRT BiV. CRI can be improved by 20% or more by using EDM to program patients to LV-only pacing at the optimal AVD or to BiV pacing at the optimal VVD. EDM technology offers the possibility of substantially improving electrical synchrony in nonresponder patients programmed with aCRT.