Persistent Iatrogenic Atrial Septal Defect Following Pulsed Field Ablation Guided by Left Atrial Intracardiac Echocardiography: Incidence, Predictors, and Clinical Outcomes.

Background: Iatrogenic atrial septal defect (iASD) is a known consequence of transseptal catheterization. Left atrial intracardiac echocardiography (LA ICE) requires additional septal instrumentation, yet data on persistent iASD after pulsed field ablation (PFA) with an LA ICE workflow remain limited. We evaluated the incidence, predictors, and one-year clinical significance of persistent iASD in this setting. Methods: Consecutive patients undergoing PFA for atrial fibrillation with LA ICE were prospectively evaluated with transthoracic echocardiography before ablation and at one year, including systematic agitated saline contrast. Persistent iASD was defined as residual interatrial shunting on color Doppler at follow-up, classified as small (<3 mm), moderate (3-5 mm), or large (>5 mm). Groups were compared by t-test and chi-square test. Results: Among 850 patients, persistent iASD was identified in 153 (18.0%) at one year; 97 (63.4%) were small and 56 (36.6%) moderate, with no large defects. All shunts were left-to-right. No stroke or transient ischemic attack, paradoxical embolism, hypoxemia, right-heart enlargement, or septal closure occurred. Persistent iASD was associated with female sex (64.7% vs 48.1%), longer septal dwell time (52{+/-}12 vs 31{+/-}11 min), higher left atrial pressure (28{+/-}4 vs 12{+/-}3 mmHg), lower LVEF (32{+/-}11% vs 54{+/-}14%), and larger-caliber sheaths ([&ge;]17 Fr; 80.4% vs 48.2%; all p<0.001). Conclusions: Persistent iASD following PFA with LA ICE occurs in approximately one in five patients but is predominantly small, exclusively left-to-right, and clinically benign at one year. Persistence is associated with mechanical and hemodynamic factors, particularly sheath caliber, rather than the ablation energy source.