AB-452663-2 LEFT ATRIAL BOX ISOLATION GUIDED BY FORCE-POWER-TIME FORMULA (ABLATION INDEX): HIGH PREVALENCE OF EPICARDIAL CONDUCTION VIA SEPTOPULMONARY BUNDLE IN ATRIAL FIBRILLATION PATIENTS

Circumferential, continuous, transmural atrial lesions are desired to facilitate pulmonary vein (PV) isolation. However, wall thickness around the PV is variable (5-6 mm in superior/anterior segments and 2-4 inferior/posterior segments). Previous experimental studies have shown that radiofrequency (RF) lesion depth diameter can be predicted by a logarithmic formula using contact force (CF), RF power application time (Force-Power-Time Formula, Ablation Index, AI). The purpose of this study was test ability AI guided ablation achieve left (LA) box isolation single encirclement examine location residual conduction (gap) within patients with fibrillation (AF). In 42 AF, LA performed 7.5Fr CF catheter (ThermoCool SmartTouch SF, Biosense Webster) CARTO system. Using (35-40Watts) (5-45g), target value 380-400 used for posterior/inferior an inter-lesion distance (ILD) 4mm 550-600 anterior/superior/septal ILD 6mm along circumference (Figure). delivered until reached values or terminated prematurely when esophageal temperature <38.5°C. After first line, activation mapping confirm identify gap locations. Total 27.2±4.6 min length 21.2±2.5 cm. Complete obtained 17/42 (40%) pts. remaining 25/42 (60%) pts, set identified earliest line only 4/42 (10%) pts (indicating endocardial gaps), whereas at site distant from 21/42 (50%) suggesting epicardial through septopulmonary bundle Focal gaps focal breakouts resulted compete all 25 effectively prevented line. via often observed (50%).