Right Ventricular Pacing from the Septum Avoids the Acute Exacerbation in Left Ventricular Dyssynchrony and Torsional Behavior Seen with Pacing from the Apex

Objective: The study objective was to compare the left ventricular (LV) dyssynchrony and torsional behavior between right ventricular apical (RVA) and right ventricular septal (RVS) pacing. Methods: Forty-six patients with symptomatic sick sinus syndrome and preserved LV function were assigned to 2 groups: RVA (n = 23) and RVS (n = 23). Echocardiographic study including two-dimensional speckle tracking imaging was performed in the AAI and DDD modes. Results: Mean QRS width during DDD mode was significantly longer with RVA pacing than with RVS pacing. Dyssynchrony, torsion, and untwisting rate during DDD mode were significantly worse with RVA than with RVS pacing. In patients with RVA pacing, there was an increase in longitudinal dyssynchrony from AAI to DDD mode that significantly correlated with the deterioration of untwisting rate. Conclusion: In bradyarrhythmic patients with preserved LV function, RVS pacing resulted in a reduced LV dyssynchrony and better torsional behavior than RVA pacing. (J Am Soc Echocardiogr 2010;23:195-200.)