Mantziari L, et al. - Using ultra-high-density mapping, researchers assessed data to describe the atrial tachycardia (AT) mechanism and investigate the relationship between substrate characteristics and ablation outcomes. In all, 50 ATs were mapped with ultra-high-density mapping in 23 procedures, and patients were followed up for ≤ 12 months. They classified the procedures into two groups: A) if there was a single AT induced (n=12) and B) if there were ≥ 2 ATs induced (n=11). Higher procedure duration, low voltage area (0.05–0.5 mV), and low voltage area indexed for volume in group B were reported. They observed similar dense scar and atrial volume between groups. They found that acute success and freedom from arrhythmia recurrence were unfavorable in group B (100% vs 77%). They suggested the prediction of recurrence with indexed low voltage area ≥0.24 cm²/mL with 100% sensitivity and 77% specificity.