Use of a biophysical model of atrial fibrillation in the interpretation of the outcome of surgical ablation procedures.

OBJECTIVE To determine the adequacy of 'in silico' biophysical models of atrial fibrillation (AF) in the design of different ablation line patterns. BACKGROUND Permanent AF is a severe medical problem for which (surgical) ablation is a possible treatment. The ideal ablation pattern remains to be defined. METHODS Forty-six consecutive adult patients with symptomatic permanent drug refractory AF underwent mitral surgery combined with non-transmural, (n=20) and transmural (n=26) radiofrequency Minimaze. The fraction of 'in vivo' conversions to sinus rhythm (SR) in both groups was compared with the performance of the fraction of 'in silico' conversions observed in a biophysical model of permanent AF. The simulations allowed us to study the effectiveness of incomplete and complete ablation patterns. A simulated, complete, transmural Maze III ablation pattern was applied to 118 different episodes of simulated AF set-up in the model and its effectiveness was compared with the clinical results reported by Cox. RESULTS The fraction of conversions to SR was 92% 'in vivo' and 88% 'in silico' (p=ns) for transmural/complete ablations, 60% respectively 65% for non-transmural/incomplete Minimaze (p=ns) and 98% respectively 100% for Maze III ablations (p=ns). The fraction of conversions to SR 'in silico' correlated with the rates 'in vivo' (r2=0.973). CONCLUSIONS The fraction of conversions to SR observed in the model closely corresponded to the conversion rate to SR post-surgery. This suggests that the model provides an additional, non-invasive tool for optimizing ablation line patterns for treating permanent AF.