Arrhythmia Risk in Conduction System Pacing

Biventricular pacing (BVP) improves pump failure outcomes but produces non-physiological repolarisation patterns which can trigger ventricular arrhythmias. Conduction system pacing (CSP) is an emerging alternative for delivering cardiac resynchronisation therapy (CRT). Acute CSP repolarisation patterns are much more physiological than BVP but there are several important unanswered questions: Acute CSP repolarisation changes often attenuate; longer-term effects are unknown. CSP leads are combined with conventional coronary sinus leads in a hybrid approach when CSP resynchronisation is incomplete. This may negate repolarisation benefits. Arrhythmogenesis requires repolarisation substrate and triggering heart-rate changes; resting heart-rate assessments do not fully realise pro-arrhythmic potential. In this fellowship I will conduct a randomised head-to-head study comparing CSP with BVP, measuring long-term repolarisation heterogeneity using validated, non-invasive, high-resolution electrical mapping (ECGi). Incomplete CSP resynchronisation will necessitate coronary sinus leads, allowing assessment of the trade-off between activation synchrony and repolarisation heterogeneity. I will perform programmed pacing manoeuvres to replicate arrhythmogenic coupling intervals, and analyse 24-hour 12-lead ECGs to assess spontaneous heart-rate variability effects. This fellowship will provide mechanistic insights into the arrhythmogenicity of BVP and CSP, informing future trial design. Physiological repolarisation with CSP could reduce fatal arrhythmias and defibrillator lead requirement, along with their associated complications.