Abstract: Objective To compare the impact of right ventricular apical (RVA) versus right ventricular outflow tract (RVOT)
pacing on left ventricular systolic synchronization. Methods Sixty patients were prospectively recruited and randomized into
RVA group (n=30) with the right ventricle leads placed in the RVA and RVOT group (n=30) with right ventricle leads placed in
the septum of the RVOT. Speckle tracking imaging was performed with 100% ventricle pacing to measure the differences in the
time to maximum left ventricle (LV) radial strain. Results In RVA group, the difference in the time to 6-segment maximum LV
radial strain after pacing was 105.27±19.74 ms, significantly greater than that in RVOT group (41.65±12.17 ms, P<0.001). The
standard difference of time to 6-segment maximum LV radial strain was also significantly greater in RVA group than in RVOT
group (42.71 ± 17.63 vs 17.63 ± 5.62 ms, P<0.001). Conclusion Left ventricle systolic synchronizaition after RVOT pacing is
superior to RVApacing.