Crista Caval Line: Lattice-Tip Pulsed Field Ablation for Right Atrial Substrate Modification.

INTRODUCTION: Pulmonary vein isolation remains central to atrial fibrillation (AF) ablation, yet right atrial substrate modification remains incompletely defined. The crista terminalis (CT) region lies close to the right phrenic nerve and may exhibit anisotropic conduction and native or functional conduction block, while also serving as a potential non-pulmonary-vein trigger site. We evaluated the acute feasibility and electroanatomic endpoint of the Crista Caval Line (CCL), a CT-guided, sinoatrial node (SN)-sparing lesion set created with lattice-tip pulsed field ablation (PFA). METHODS AND RESULTS: We prospectively enrolled 36 consecutive patients undergoing CCL creation during repeat AF ablation or ablation for non-paroxysmal AF. Pre-CCL sinus-rhythm high-density right atrial activation mapping was performed in all patients. CT-related conduction delay or block was observed in 27 patients (75.0%). In 14 patients (38.9%) with an apparent CT block line, the inferior application-set edge was aligned to the block line; in the remaining 22 patients without an apparent block, placement was primarily guided by intracardiac echocardiography. The CCL was positioned posterior to the CT, with the lateral margin of its superior application set kept approximately 15 mm posterolateral to the earliest mapped sinus activation site for SN protection. The CCL measured 78.8 [66.4-86.0] mm from first to last tag and required 26 [22-30] PFA applications over 370 [282-481] s. First-pass bidirectional transverse conduction block was confirmed in all patients by postablation activation mapping and differential pacing from both sides of the CCL. Next-day inspiratory/expiratory chest radiography showed no abnormality suggestive of phrenic nerve palsy; no pacemaker-requiring SN dysfunction or other clinically apparent collateral injury occurred. CONCLUSIONS: A CT-guided, SN-sparing CCL can be reproducibly created with lattice-tip PFA, producing a first-pass bidirectional transverse conduction block without clinically apparent phrenic nerve palsy. These findings establish acute feasibility and an electroanatomic endpoint; lesion durability, arrhythmia recurrence, and incremental clinical benefit require further study.