Mapping and ablation of left atrial tachycardias occurring after atrial fibrillation ablation

Regular left atrial tachycardias are a frequent complication of atrial fibrillation ablation procedures. The arrhythmia mechanism appears to be due to focal pulmonary vein reentry in patients who undergo only electrically guided pulmonary vein isolation. The most common site of origin is the septal and inferior aspect of the right pulmonary veins. Attention to avoiding gaps when ablating along this region will minimize the occurrence of these tachycardias. In patients who also undergo linear left atrial ablation lesions and in patients with significant left atrial disease, macroreentry around the mitral annulus or ipsilateral pulmonary veins is frequently observed. Confirming electrical block across any prophylactic linear lesions (mitral isthmus line, left atrial roof line) likely is important for preventing gap-related proarrhythmic tachycardias. When tachycardias do occur, temporizing with ventricular rate control and cardioversion is initially indicated, as approximately one third of these atrial tachycardias may resolve with time. For tachycardias persisting after ablation, detailed three-dimensional activation and entrainment mapping can facilitate localization of the atrial tachycardia and guide the approach to eliminating the arrhythmias. This review provides a systematic approach to the evaluation, diagnosis, localization, and elimination of left atrial tachycardias occurring after atrial fibrillation ablation.