ABSTRACTS S166 Heart, Lung and Circulation Abstracts 2009;18S:S1–S286 375 UTILITY OF INTRACARDIAC ECHOCARDIOGRA- PHY IN CATHETER ABLATION OF ATRIAL FIBRILLA- TION S. Townsend 1 , N. Wessel 2 , G. Scalia 1 , K. Phillips 1, 1 Greenslopes Private Hospital, Newdegate St, Brisbane, Aus- tralia 2 Johnson & Johnson Medical Pty Ltd, Australia Background: Intracardiac echocardiography (ICE) may confer additional benefits during left atrial catheter abla- tion procedures, contributing to improved safety and successful outcomes. We report on our initial experience using ICE in patients undergoing catheter ablation for atrial fibrillation. Methods: A 10Fr Acunav ® ICE catheter was posi- tioned within the right atrium for continuous imaging at 5–8.5 mHz during catheter ablation procedures for atrial fibrillation. Imaging was specifically employed to guide transseptal puncture, verify the position of catheters within the pulmonary veins (PVs) and left atrium, check PV velocities pre- and post-procedure, and to monitor for complications of thrombus formation or pericardial effu- sion. Results: Procedures were performed in 44 patients. All transseptal punctures (88 of 88) were successful. 173 of 174 pulmonary veins were successfully electrically isolated. No significant elevations in PV velocity were observed pre- or post-procedure. There were no intraprocedural compli- cations. Conclusions: Continuous ICE use during catheter abla- tion procedures for atrial fibrillation has unique imaging benefits which may contribute to improved safety and pro- cedural outcomes. doi:10.1016/j.hlc.2009.05.377 376 VAGAL PAROXYSMAL ATRIAL FIBRILLATION: PREVALENCE AND ABLATION OUTCOME IN PATIENTS WITHOUT STRUCTURAL HEART DISEASE Raphael Rosso , Paul B. Sparks, Joseph B. Morton, Peter M. Kistler, Jitendra K. Vohra, Karen Halloran, Caroline Medi, Jonathan M. Kalman The Department of Cardiology, Royal Melbourne Hospital and the Department of Medicine, University of Melbourne, Mel- bourne, Australia Introduction: In patients with paroxysmal AF referred for antral pulmonary vein isolation (APVI) we investigated the prevalence of vagal and adrenergic triggers and the ablation success rate in patients with these triggers com- pared to patients with random AF. Methods and results: 209 consecutive patients under- went a first APVI due to symptomatic drug refractory paroxysmal AF. Patients were diagnosed as vagal or adren- ergic AF if >90% of AF episodes were related to recognized vagal or adrenergic triggers. Otherwise a diagnosis of random AF was made. Clinical, ECG and Holter follow up was performed 3 monthly and for symptoms. Of 209 patients, 57 (27%) had vagal AF, 14 (7%) adrenergic AF and 138 (66%) random AF. Vagal triggers were sleep (96.4%), post-prandial-rest (96.4%), late post-exercise (51%), cold stimulus (20%), coughing (7%) and swallowing (2%). At APVI 94.3% of patients had successful isolation of all veins. Twenty-five (12%) patients had a second APVI. At a fol- low up of 21 ± 15 months, the percentage of patients free of AF was 75% in the vagal group, 86% in the adrener- gic group and 82% for random AF (p = 0.51). Forty-eight (28.6%) patients were taking previously ineffective anti- arrhythmic agents with no difference between the three groups. In 21 vagal patients who had AF recurrence, the vagal pattern was maintained in 20. Conclusions: In patients with PAF and no structural heart disease referred for APVI, vagal AF is present in approximately one quarter. APVI is equally effective in patients with vagal AF as in adrenergic and random AF. Vagal AF Adrenergic AF Random AF p-Value Number (%) 57 (27) 14 (7) 138 (66) Mean age (years) 58 ± 10 57 ± 10 56 ± 10 0.69 Gender (male/female) 43/14 13/1 104/34 0.33 Hypertension (%) 13 (22.8%) 3 (21.4%) 40 (29.0%) 0.61 Left atrium size (cm) 4.1 ± 0.7 3.9 ± 0.4 4.1 ± 0.6 0.82 Mean duration of AF (months) 112 ± 81 120 ± 100 103 ± 62 0.68 Number of AAD (n) 1.5 ± 0.7 1.2 ± 0.6 1.5 ± 0.7 0.34 Patients requiring 2nd procedure (%) 7 (12%) 1 (7%) 17 (12%) 0.85 Number of procedures (n) 1.2 ± 0.4 1.1 ± 0.3 1.2 ± 0.4 0.81 Mean follow up (months) 21 ± 15 21 ± 13 22 ± 15 0.92 Freedom from AF (%) 43 (75%) 12 (86%) 113 (82%) 0.51 Freedom from AF on AAD (%) 12 (27.9%) 2 (16.7%) 34 (30.1%) 0.62 doi:10.1016/j.hlc.2009.05.378 377 VALIDATION OF TEMPLATE MATCHING FOR ASSESSMENT OF LOCAL WAVE FRONTSTABILITY P. De Sciscio , P. Kuklik, A.G. Brooks, M.K. Stiles, C.X. Wong, B. John, D. Lau, H. Dimitri, G.D. Young, P. Sanders Cardiovascular Research Centre, Department of Cardiology, Royal Adelaide Hospital and the Disciplines of Medicine and Physiology, University of Adelaide, Adelaide, South Australia, Australia Introduction: Sites of high dominant frequency (DF) and/or fractionation have been implicated in the main- tenance of permanent AF. Analysis of wave front characteristics may provide more significant information regarding the mechanism of AF. We aim to validate a new method for quantifying activation temporal stability dur- ing AF.