Chronic effect of right ventricular pacing on left ventricular rotational synchrony in patients with complete atrioventricular block.

BACKGROUND

Chronic effect of right ventricular (RV) pacing on left ventricular (LV) rotational synchrony is unknown. The aim of this study is to assess chronic effect of RV pacing on LV rotational synchrony using two-dimensional ultrasound speckle tracking imaging.

METHODS AND RESULTS

Thirty-one patients who underwent dual-chamber pacemaker implantation for complete atrioventricular block, and age- and sex-matched 10 healthy controls were assessed. We divided our patients into RV apical (RVA, n = 16) and RV outflow tract (RVOT, n = 15) pacing groups. We compared echocardiographic parameters such as LV rotational synchrony between pacing groups and healthy control. We defined Q to peak rotation interval as the interval from the beginning of the Q-wave to the peak apical counter-clockwise or peak basal clockwise rotation. We calculated apical-basal rotation delay by subtracting basal Q to peak rotation interval from apical one as the representative of rotational synchronization. Apical-basal rotation delay of RVA pacing was significantly longer than that of healthy control (100 ± 110 vs. -6 ± 15 ms, P = 0.002), while there was no statistically significant difference between RVOT pacing and healthy control (-3 ± 99 vs. -6 ± 15 ms, P = 0.919).

CONCLUSIONS

LV rotation during RVOT pacing is synchronous at 15 months after pacemaker implantation, while RVA pacing provokes LV rotational dyssynchrony by inducing delayed apical rotation at 7 years after pacemaker implantation in patients with complete atrioventricular block.