Right ventricular apical (RVA) pacing can lead to mechanical dyssynchrony in the left ventricle, increasing atrial fibrillation and the incidence of heart failure. Right ventricular septal (RVS) pacing may attenuate the mechanical dyssynchrony and has been proposed as an alternative, but data from rigorous studies are limited. S. Azzaz, S. Kacem, S. Ouali, and colleagues, Sahloul Teaching Hospital, Sousse, Tunisia, conducted a randomized study to determine whether RVS pacing is superior to RVA pacing in pacemaker (PM) implantation by comparing left ventricular (LV) function and dyssynchrony parameters resulting from interventricular septal vs RVA pacing.

Patients with high-degree atrioventricular block who were candidates for dual-chamber PM implantation were randomized to either apical (group A) or septal (group B) right ventricular lead placement. Levels of LV function and dyssynchrony were determined by echocardiography at the time of PM implantation and 6 months later. Patients with coronary artery disease, prominent valvular heart disease, and/or cardiomyopathies were excluded from the study. Lead implantation was performed under fluoroscopy control. A total of 57 patients were randomized to group A (n = 29) and group B (n = 28). In the overall population, the mean age was 69 years, about 50% were male, 60% had hypertension, and 20% had diabetes; 95% experienced cumulative ventricular pacing. Follow-up data at 6 months were available for 48 patients. All analyses are exploratory.

Postprocedure and at 6 months, septal pacing was associated with a significantly lower Tei index (a global parameter of cardiac function combining systole and diastole information) than apical pacing. In addition, the E/A ratio was significantly higher in septal compared with apical pacing, and global longitudinal strain (GLS) was improved with septal compared apical pacing. Multiple parameters were nominally different between the groups after the procedure and at 6 months; radial and longitudinal dyssynchrony and septal-to-lateral wall delay were nominally higher in the apical group compared with the septal group.

Although statistically significant differences in dyssynchrony were not present, the investigators said that the septal pacing seemed to be associated with better global LV function and that they recommend septal as an alternative to apical stimulation. The investigators also said that GLS continued to be better in the septal group (−15.8 vs −14.4; P = .003) 6 months after PM implantation. The Tei index continued to be seen as lower in the septal group compared with the apical group (0.43 vs 0.57, respectively; P = .002).