Conduction System Pacing Significantly Reduces PICM and CRT Upgrade Need in AV Block Patients: CSPACE Trial
Australia: Patients with atrioventricular (AV) block who undergo conduction system pacing (CSP) experience significantly better clinical outcomes compared to those receiving right ventricular septal pacing (RVsP), according to findings from the CSPACE randomized controlled trial published in the Journal of the American College of Cardiology (JACC).
Traditionally, AV block patients have been managed using right ventricular pacing. However, this approach has been linked to serious risks, including pacing-induced cardiomyopathy (PICM), increased rates of heart
failure hospitalizations, the need for biventricular cardiac resynchronization therapy (CRT) upgrades, and a higher risk of mortality. CSP has emerged as a physiological alternative to conventional pacing, aiming to maintain ventricular synchrony and reduce these complications by stimulating the heart's natural conduction pathways.
The CSPACE trial, led by Dr. Chee Loong (Dominic) Chow from the University of Melbourne, Australia, enrolled 202 patients requiring pacing for AV block who had no indications for CRT. Participants were randomly assigned in a 1:1 ratio to receive either CSP or RVsP. The primary composite endpoint included the occurrence of PICM, CRT upgrades, heart failure hospitalizations, and all-cause mortality. The study followed patients for an average of approximately 25 months to assess outcomes.
Key Findings:
- CSP was successfully implemented in 88.1% of patients assigned to the intervention arm.
- When compared to RVsP, CSP demonstrated a significant reduction in the composite outcome rate (7.17 vs. 20.69 events per 100 person-years; hazard ratio [HR] 0.35).
- This improvement was primarily attributed to a marked decrease in PICM (4.58 vs. 14.69 events per 100 person-years; HR 0.31).
- CSP completely eliminated the need for CRT upgrades (0 vs. 1.92 events per 100 person-years), further highlighting its clinical advantage.
- The trial did not find statistically significant differences for heart failure hospitalizations (HR 0.16) or all-cause mortality (HR 0.61), though the trends consistently favored CSP.
- The conduction system approach was associated with a higher incidence of lead revisions compared to RVsP (7.9% vs. 1.0%), which remains a key consideration for clinical practice.
The investigators concluded that CSP offers superior outcomes for AV block patients without CRT indication, supporting its adoption as an initial pacing strategy. Although current guidelines provide a Class II recommendation for CSP in patients with a high ventricular pacing burden, the CSPACE trial strengthens its position as a preferred option. Nevertheless, clinicians should carefully weigh the increased risk of lead revisions against the significant long-term benefits of avoiding PICM and reducing CRT upgrades.
"Overall, the findings from the CSPACE trial provide compelling evidence that CSP could become the standard of care in AV block management, paving the way for improved long-term cardiac health in this population," the authors wrote.
Reference:
Chow, C, Wong, C, Sutherland, N. et al. Clinical Outcomes of Conduction System Pacing vs Right Ventricular Septal Pacing in Atrioventricular Block: The CSPACE Randomized Controlled Trial. JACC. 2025 Aug, 86 (8) 563–573. https://doi.org/10.1016/j.jacc.2025.06.043
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