lar model reproducing experimental observed atrial cellular properties. Sustained AF, typical and atypical flutter could be reproduced using a burst-pacing protocol. Based on a model of chronic AF, surgical/ radiofrequency (RF) ablation lines were implemented by making the cardiac cells located on the ablation lines non conductive. Several published ablation patterns were implemented in the computer model and their results compared to clinical data. We thus evaluated the standard Maze llI

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... ure and less invasive patterns involving fight and/or left ablation lines. Success rate, time to AF termination and AF reinitiation capacities were assessed for each studied pattern. Results: among all simulated ablation patterns, the most efficient is the Maze llI procedure with a 100% success rate (no significant difference compared with the clinical success of 98% published by Cox in 1993). We observed that the most complex ablation patterns led both to the best success rate and shortest time to AF termination. Ablation patterns involving lines in the right or left atrium led to success rates in the range 60-65% while those combining lines in both atria showed an increased rate in the range from 80-100%. For example, a simplified Maze pattern led to success rate of 88% (comparable to success rate of 92% in our clinical experience using RF ablation). However, some specific ablation lines such as those connecting pulmonary veins and mitral valve annulus appear more sensitive to gaps simulating non-transmurality; this resuks in a lower performance generally manifested by the appearance of uncommon flutter after ablation. Conclusions: this simulation study confirms the good performance of the standard Maze llI procedure in treating chronic AF. It suggests that less invasive patterns need to include ablation lines in both atria and that discontinuities in specifically located ablation lines lead to a decrease in success rate. 566 A prospective and comparative study of different techniques for atrial fibrillation ablation