METHODS
The single-center CHAOS study prospectively included all patients scheduled for reentrant AT ablation from May 2017 to December 2019, excluding patients diagnosed with CTI-dependent atrial flutter, in which the tachycardia circuit was deemed non-mappable due to continuous circuit modification or conversion to atrial fibrillation. All patients had pre-procedural documentation of reentrant AT on the surface ECG based on: 1) the presence of continuous atrial activity on the surface ECG, or: 2) in patients with focal AT pattern, the arrhythmia behavior (stable cycle length without modification at onset or end) and patient characteristics (diseased atria).13 Patients could present to the ablation procedure in sinus rhythm, AT or AF.
Written informed consent was obtained before the procedures and patient data were collected in a dedicated database. The study complied with the Declaration of Helsinki and received prior approval by the ethics committee of our institution.