Ablation of consecutive atrial tachycardia (AT) after ablation of atrial fibrillation (AF) or cardiac surgery can be challenging due to complex substrate and AT mechanisms. A substantial portion of patients is known to show various tachycardias and recurrences occur in a noticeable number of cases. With the availability of novel ultra-high-density mapping techniques characterization and understanding of AT mechanisms and underlying substrate can be improved. Aim of this prospective, multi-center, randomized study is to compare a standard AT ablation approach versus minimalized ablation of the clinical AT in regards to arrhythmia free survival.

Inclusion Criteria:

• Consecutive AT subsequent to prior AF ablation procedure or cardiac surgery
• Surface ECG-documentation of AT as primary clinical arrhythmia
• ECG indicating stable, map-able AT (stable activation sequence, and CL stability) with cycle length ≥ 200ms

Exclusion Criteria:

• < 18 years
• No previous atrial fibrillation ablation procedure or cardiac surgery
• Pregnant women or women of childbearing potential without a negative pregnancy test within 48 hours prior to treatment
• History of hemorrhagic diathesis or other coagulopathies
• Contraindications for oral anticoagulation
• Hyper- or hypothyroidism
• Has any condition that would make participation not be in the best interest of the subject