Ventricular Dyssynchrony based on echocardiographic variables and exercise tolerance After right ventricular pacing: Impact of alternative septal lead locations.

Abstract

We investigated the impact of alternative locations of right ventricular (RV) pacing on left ventricular function and its relation to exercise capacity. Fifty patients who received a single lead pacemaker were divided according to RV pacing site into group 1 "high septum" (n=15), group 2 "mid-septum" (n=25), and group 3 "low septum" (n=10) using a documented fluoroscopic method. Dyssynchrony parameters were obtained using different echocardiographic parameters. Their exercise tolerance was evaluated after 6months of pacemaker implantation using 6minutes walk test (6 MWT). We found a lesser degree of dyssynchrony in mid-location and high location compared with low location pacing (radial dyssynchrony: P<.001; maximum temporal difference: P<.01; inter-ventricular mechanical delay: P<.05, standard deviation of time-to-peak strain by tissue Doppler: P<.05). Sm was significantly increased 6months following pacemaker implantation in group 1 and group 2 in contrast to group 3 patients (P<.05). Importantly, E/e' increased significantly (P<.001) in patients with low septal location pacing. Furthermore, 6 MWT distance was significantly improved (P<.001) in favor of groups 1 and 2. Importantly, the intra-ventricular dyssynchrony with speckle tracking was considerably less in group 1 and 2 patients. Tps-SL≤120ms was the optimal value to predict improvement in functional capacity following high to mid-septal pacing locations. There was significant improvement of functional capacity after RV pacing in high and mid-septal locations compared with low septal location. This was associated with a lesser degree of dyssynchrony in favor with mid- to high septal location.