Macroreentrant atrial tachycardia detouring the epicardium at the anterior wall of the left atrium.

A 79-year-old woman with a history of pulmonary vein isolation for persistent atrial fibrillation was admitted for recurrence of atrial tachycardia, with a tachycardia cycle length of 236 milliseconds. The ultra-high-resolution mapping system revealed that tachycardia circuit detouring the epicardium at the anterior wall scar and breaking through to the endocardium below the left atrial appendage. Radiofrequency energy was applied to this site, which successfully terminated the tachycardia. This case suggests that epicardial conduction could occur even at the left atrial anterior wall and identifies a variation in epicardial conduction around the left atrium, which could be a tachycardia circuit.