Abstract 1588: Beneficial Effect of Right Ventricular Outflow Pacing on Left Ventricular Dyssynchrony and Myocardial Torsion in Comparison with Right Ventricular Apical Pacing
Background: It has become clear that a long-standing right ventricular apical pacing (RVA) causes left ventricular (LV) asynchronous motion, resulting an increased incidence of congestive heart failure. Right ventricular outflow pacing (RVOT) is an alternative pacing method to avoid the harmful effects of RVA.
Aim: This study was aimed to clarify the clinical impact of RVOT on LV dyssynchrony and myocardial torsion in comparison with RVA.
Methods: This study included forty-eight patients without structural heart disease (mean age: 72 +/−8 years) who had been received permanent pacemaker implantation for symptomatic brady-arrhythmias, and we divided into 2 groups according to the RV pacing site (RVA: 26 patients, RVOT: 22 patients). Echocardiographic studies were performed with GE Vivid 7 Dimension at one year after pacemaker implantation. We assessed LV systolic dyssynchrony using 2D speckle tracking imaging, and its index was defined as the SD of time to peak longitudinal strain (Ts-SD) at the 18 segments from the apical 3 views. In addition, we calculated LV torsion defined as the difference between basal and apical rotations from the short axial views.
Results: The mean QRS duration and axis were significantly different between RVA and RVOT (QRS duration: 155 vs. 138 ms, QRS axis: −69 vs. 57 degrees, P <0.05, respectively). The LV ejection fraction (EF) was significantly decreased in RVA in comparison with RVOT (55+/−9 vs. 66+/−8 %, P< 0.01). The Ts-SD in patients with RVA was significantly increased than those with RVOT (89+/−37 vs. 44+/−18 ms, P< 0.01). In addition, LV torsion was significantly decreased in patients with RVA than those with RVOT mainly due to the reduction of basal LV rotation (11+/−4 vs. 17+/−5 degrees, P< 0.01). Furthermore, the Ts-SD is significantly related to EF and LV torsion in this study population (EF: r= 0.570, P< 0.01, LV torsion: r=0.435, P< 0.05).
Conclusion: Right ventricular outflow pacing could reduce LV systolic dyssynchrony and maintain myocardial torsion in comparison with right ventricular apical pacing, which might be related to the preservation of LV systolic performance.