Clinical Outcomes of Conduction System Pacing vs Right Ventricular Septal Pacing in Atrioventricular Block: The CSPACE Randomized Controlled Trial

Abstract

Background: Patients with atrioventricular (AV) block receiving right ventricular (RV) pacing are at risk of pacing-induced cardiomyopathy (PICM), need for upgrade to biventricular cardiac resynchronization therapy (CRT), heart failure hospitalization (HFH), and mortality. Conduction system pacing (CSP) is a promising pacing strategy to mitigate these adverse outcomes.

Objectives: The aim of this study was to compare the clinical outcomes between RV septal pacing (RVsP) and CSP.

Methods: A randomized controlled trial (RCT) was performed in 202 consecutive patients with pacing indication for AV block without CRT indication, with a 1:1 randomization allocation ratio between RVsP and CSP. The primary outcome was a composite endpoint of PICM, upgrade to biventricular CRT, HFH, and all-cause mortality. This trial was registered with the Australian New Zealand Clinical Trials Registry.

Results: CSP was successful in 89 of 101 patients (88.1%). After a mean follow-up period of 25.2 ± 11.8 months, CSP was associated with lower composite endpoint (7.17 vs 20.69 events per 100 person-years; HR: 0.35; 95% CI: 0.19-0.64; P < 0.001) primarily driven by lower PICM (CSP 4.58 vs RVsP 14.69 events per 100-person-years; HR: 0.31; 95% CI: 0.15-0.67; P = 0.002) and need for CRT upgrade (0 vs 1.92 events per 100-person-years; HR: 1.65e^-9; 95% CI: 0-∞; P = 0.043). There was no difference in HFH (CSP 0.48 vs RVsP 2.92 events per 100-person years; HR: 0.16; 95% CI: 0.02-1.37, P = 0.057) or all-cause mortality (CSP 2.86 vs RVsP 4.72 events per 100-person-years; HR: 0.61; 95% CI: 0.22-1.69; P = 0.337). Lead revision occurred more with CSP (8 patients [7.9%] vs 1 patient [1.0%]; P = 0.017).

Conclusions: This RCT demonstrates the superiority of CSP over RVsP in achieving improved clinical outcomes and supports the indication of CSP as an upfront pacing technique for patients with AV block. (CSPACE: A Randomised Controlled Trial Comparing Right Ventricular Pacing with Conduction System Pacing; ACTRN12619001613190).

Keywords: His-bundle pacing; atrial fibrillation; atrioventricular block; cardiac resynchronization therapy; conduction system pacing; left bundle branch pacing; pacing-induced cardiomyopathy; right ventricular pacing.