Open‐Window Mapping for Accessory Pathway Ablation: Influence of Catheter Design on Mapping Performance

ABSTRACT Background Open‐window mapping (OWM) using the extended early‐meets‐late (EEML) algorithm is widely used for accessory pathway (AP) localization. However, the impact of catheter design on mapping performance and procedural outcomes remains unclear. Methods We retrospectively analyzed 43 consecutive patients undergoing OWM‐guided AP ablation. Twenty‐four patients were mapped using an 8‐spline high‐density catheter and 19 using a conventional 5‐spline catheter. Mapping characteristics and ablation outcomes were compared. Results The 8‐spline catheter was associated with higher mapping density (7974 [5618–11 017] vs. 2485 [734–12 577] points; p < 0.001) and shorter mapping time (11.0 [8.5–14.8] vs. 28.0 [15.0–40.0] minutes; p < 0.001). The EEML‐derived AP gap width was narrower in the 8‐spline group (6.1 [5.3–7.5] vs. 8.3 [2.9–15.6] mm; p = 0.023), with lower EEML thresholds required for visualization ( p = 0.003). First‐pass AP elimination was achieved in all patients in the 8‐spline group (100%) compared with 68% in the 5‐spline group ( p = 0.004), with fewer radiofrequency applications required ( p = 0.048). Fluoroscopy time and complication rates were similar between groups. Conclusion Compared with a conventional 5‐spline catheter, an 8‐spline high‐density catheter was associated with improved mapping efficiency and a higher rate of first‐pass ablation success. These findings suggest that catheter design may influence procedural performance in OWM‐guided AP ablation.