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

Objective: We investigated the impact of alternative locations of right ventricular (RV) pacing on left ventricular function and its relation to exercise capacity.

Methods: 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 6 months of pacemaker implantation using 6 minutes walk test (6 MWT).

Results: 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 6 months 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 ≤ 120 ms was the optimal value to predict improvement in functional capacity following high to mid-septal pacing locations.

Conclusion: 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.