Surgical approaches to atrial fibrillation.

Abstract

Atrial fibrillation (AF) remains an unsurmounted hurdle toward the cure of supraventricular arrhythmias. Despite its high prevalence, a definitive treatment approach has not been established. AF is triggered in most cases by early premature atrial beats and is maintained by anomalies of the substrate. Elimination or modification of either one or both may be effective in the cure of AF. Surgical ablation, which originated with the favorable results of the Maze procedure developed by Cox, has an important role in the cure of AF associated with heart diseases that require cardiac surgery. This is due to the high success rate and to the simplification of the procedure now used which has resulted in reduction of the procedural time and complications. Various techniques have been proposed, however, it is noteworthy that the posterior part of the left atrium and the ostia of pulmonary veins are involved in all approaches despite the different energy sources used (radiofrequency or cryo energy) and the different design of the intended lesion. These results imply that the posterior part of the left atrium is crucial in the genesis and maintenance of atrial fibrillation. On the other hand, it is not clear if the results of the ablation are due to the linear lesions that modify the substrate or to the electrical isolation that eliminate the triggers. A thorough electrophysiological evaluation post ablation has been performed only in few cases. Greater understanding of the mechanism of success of surgical ablation may advance the development and success of other approaches. Considering that surgical ablation is usually performed in patients with permanent AF, linear lesions modifying the substrate together with pulmonary vein isolation have shown better results than the elimination of the triggers with a pure electrical isolation of the pulmonary veins. Prevention of AF recurrences has been relatively good, however some severe complications (atrioesophagus fistula, coronary artery damage, etc.) have been reported. Considering the relatively benignity of AF in absence of associated cardiopathy, the risk of complications should discourage widespread application of surgical ablation in patients with lone AF. On the contrary it should be routinely proposed in most patients with permanent or paroxysmal AF undergoing cardiac surgery.