Abstract 2823: Right Ventricular Septal Versus Apical Pacing: Long Term Impact On Left Ventricular Synchrony And Function
Background: Right ventricular (RV) septal pacing has been advocated as an alternative to RV apical pacing to avoid long term detrimental effects. There is conflicting evidence on the benefits of RV septal pacing. No studies have previously compared left ventricular (LV) strain and dyssynchrony between different pacing sites and utilized echocardiography to determine pacing sites.
Methods: 55 patients (22 normal controls, 17 RV septal and 17 RV apical pacing) were recruited. LV circumferential and radial strain were determined in the midventricular short axis views. Circumferential and radial strain synchrony, and longitudinal systolic (SDTs) and diastolic (SDTe) dyssynchrony indices were determined. Echocardiographic determination of pacing sites were compared with ECG and chest x-ray (CXR).
Results: The median pacing durations were 436 days for RV septal and 2398 days for RV apical pacing. Mean QRS duration were significantly shorter for septal than apical pacing and normal controls (139.8 ± 22.6 vs. 162.4 ± 22.9 vs. 85.9 ± 15.2 msec respectively, p < 0.001). LV mass index, end-systolic volume index and ejection fraction were more impaired in RV septal than apical pacing (108.2 ± 27.2 vs. 91.5 ± 15.4 g/m2, 21.3 ± 3.7 vs. 19.4 ± 9.3mL/m2, 47.6 ± 8.5 vs. 54.2 ± 7.8% respectively, all p < 0.05). RV septal pacing was associated with more impaired circumferential strain (p < 0.001) and worse circumferential strain dyssynchrony (p = 0.02) than apical pacing and normal controls. There were no significant differences in radial strain, radial strain dyssynchrony or SDTs. RV septal pacing consisted of a heterogeneous group of different pacing sites on echocardiography, and there was only modest agreement between echocardiographic, ECG and CXR determinations of pacing sites.
Conclusions: RV septal pacing was associated with poorer long term LV function and greater dyssynchrony than RV apical pacing and normal controls.