The Value of Inter-Lesion Time in Linear Lesion Formation Across Varying Catheter Angles and Inter-Lesion Distances.

BACKGROUND: Our previous ex-vivo study showed that shorter inter-lesion time (ILT), defined as the interval between consecutive ablations, enhances lesion depth and may reduce residual conduction during linear ablation. Its impact under practical scenarios, such as parallel catheter orientation and shorter inter-lesion distance (ILD), remains unclear. To investigate how ILT, catheter orientation, and ILD affect lesion depth during linear ablation using high-power (HP) and very-high-power short-duration (vHPSD) settings in an ex-vivo model. METHODS: Linear lesions (six per line) were created using the QDOT MICRO catheter (Biosense Webster). Phase 1 evaluated catheter orientation (parallel vs. perpendicular), and Phase 2 compared ILDs (6 mm vs. 4 mm). Minimum perpendicular inter-lesion depths and maximum lesion depths were measured under short ILT (15 s) or long ILT (60 s) using vHPSD (90 W/4 s) or HP (50 W, Ablation Index 350). RESULTS: Short ILT consistently increased maximum and inter-lesion depths across all settings. In Phase 1, parallel orientation produced deeper lesions than perpendicular under HP, whereas under vHPSD, parallel orientation generated shallower lesions. In Phase 2, lesions at ILD 4 mm were deeper than at 6 mm for the same ILT. Notably, short ILT at ILD6 mm achieved inter-lesion depths comparable to long ILT at ILD4 mm, suggesting an additive benefit of ILT shortening, though it cannot replace a short ILD. CONCLUSION: In this proof of concept study, shorter ILTs enhanced lesion depth across all conditions. The effect of catheter orientation varied between HP and vHPSD, suggesting that the optimal strategy to maximize ILT effectiveness depends on ablation setting.