Differences in left ventricular dyssynchrony between high septal pacing and apical pacing in patients with normal left ventricular systolic function

SummaryBackground and purposePermanent right ventricular apical pacing can result in heart failure due to ventricular mechanical dyssynchrony. The purpose of the study was to define differences in left ventricular dyssynchrony between high septal pacing and apical pacing using tissue Doppler imaging (TDI) and two-dimensional (2D) speckle-tracking echocardiography (STE).MethodsThe subjects were 60 patients with normal left ventricular systolic function who underwent implantation of a permanent pacemaker. Patients were divided into two groups with high septal pacing (n=36) and conventional right apical pacing (n=24). Left ventricular dyssynchrony was measured using TDI and 2D-STE. The time difference (TD) between the earliest and latest activated segments obtained from each systolic velocity curve by TDI was defined as TD-TDI. The time differences obtained from systolic strain curves obtained by 2D-STE were defined as TD-RS for radial strain, TD-CS for circumferential strain, and TD-LS for longitudinal strain.ResultsThe high septal pacing group had significantly shorter TD-TDI (20.0±24.3ms vs. 59.7±43.0ms, p<0.0001), TD-RS (13.5±19.9ms vs. 45.8±24.6ms, p