Patient Characteristics
A cohort of 65 consecutive patients with AT/flutter who were referred to our institution for radiofrequency (RF) catheter ablation between April 2018 and December 2020 were evaluated retrospectively. Of these 65 patients, a total of 8 patients (5 men and 3 women) with more than two types of stable ATs during ablation were included in this study. The patients with unstable cycle length (CL), unsustainable ATs and in whom ablation failed were excluded due to the unascertainable mechanism of these ATs. Seven patients had permanent AT, and 1 patient had paroxysmal AT for an average of 12 months (range, 1 month to 36 months) despite the use of antiarrhythmic drugs. All patients had been on oral anticoagulants before ablation. Transesophageal echocardiography was performed to rule out left atrial (LA) thrombi in all patients. Oral anticoagulants were stopped at admission and replaced with intravenous heparin to maintain partial thromboplastin time at 2 to 3 times the control value. This was stopped 6 to 8 hr before ablation for transseptal puncture. All patients gave written informed consent, and the study protocol was approved by the local Research and Human Ethics Committees.