Right ventricular septal pacing in patients with right bundle branch block

•Effect of cardiac resynchronization therapy for patients with right bundle branch block is controversial.•We hypothesized that pacing the right ventricular septum (RVS) could restore more normal activation in these patients.•RVS pacing in patients with RBBB resulted in a marked decrease in QRS duration and normalization of the ECG.

BackgroundCardiac resynchronization therapy (CRT) has been shown to improve left ventricular (LV) function and exercise performance in patients with left bundle branch block. Patients with right bundle branch block (RBBB) do not have a similar positive response to standard CRT. We hypothesized that single site pacing of the right ventricular septum (RVS) near the proximal right bundle could restore more normal activation of the LV in RBBB patients.Methods78 consecutive patients (56 M, 22 F) with baseline RBBB underwent pacemaker or ICD implantation. Leads were placed in the right atrium and RVS.ResultsBaseline QRS duration was 120-220 ms (mean QRSd = 147 ms). At the optimal AV delay, the fused QRSd was 56-160 ms (mean QRSd = 112 ms). The mean decrease in QRSd was 34 ± 20.4 ms (p < 0.001).ConclusionRVS pacing in patients with RBBB resulted in a marked decrease in QRS duration and often normalized the ECG.