Behavior-Based Electrogram Mapping Identifies Potential Functional Substrates in Atrial Fibrillation: The KSP-AF Randomized Study

BACKGROUND AND AIMS: Conventional substrate mapping during atrial fibrillation (AF) may fail to capture dynamic electrogram behavior. Key spatiotemporal potentials (KSPs) are electrogram patterns identified by their temporal behavior during AF. We evaluated whether KSP-guided ablation improves outcomes beyond pulmonary vein isolation (PVI) and characterized their short-term frequency consistency. METHODS: In this single-center randomized study, 100 patients with paroxysmal or persistent AF undergoing first-time ablation were assigned to PVI plus KSP-guided ablation or PVI alone. The primary endpoint was 24-month single-procedure freedom from documented AF recurrence without antiarrhythmic drugs. Dominant frequency (DF) analysis included 93 KSP regions from 18 patients, assessed across four consecutive 5-second epochs. RESULTS: Acute AF termination occurred in 68% of patients with PVI + KSP versus 26% with PVI alone (P < 0.001). At 24 months, freedom from AF recurrence was 74% versus 48% (HR 0.38, 95% CI 0.18-0.79; P = 0.010), and freedom from AF/atrial tachycardia recurrence was 68% versus 46% (HR 0.49, 95% CI 0.25-0.97; P = 0.040). Within-recording temporal DF variability was low (coefficient of variation, 4.8 ± 1.2%). CONCLUSION: Adding KSP-guided ablation to PVI improved acute and 24-month rhythm outcomes in this single-center trial. These findings support further evaluation of behavior-based mapping to identify potential functional AF substrates and require multicenter confirmation.