Left-sided Macro-reentry or Right-sided Focal Tachycardia in Patients with Prior Pulmonary Vein Isolation: A Tale of Two Atria.

We report on three patients with prior pulmonary vein isolation who presented with atrial tachycardia/atrial flutter. During electrophysiology study, the whole tachycardia cycle length was mapped to the left atrium. Multiple ablation attempts failed to terminate the tachycardia and, subsequently, right atrial mapping revealed a focal early site of origin near the superior vena cava-right atrial junction in two patients and outside the coronary sinus ostium in one patient. In this report, we discuss the probable mechanism of these tachycardias.