ABC | Volume 114, Nº5, May 2020

Original Article Risk of Atrial Fibrillation after Ablation of Cavotricuspid Isthmus- Dependent Atrial Flutter: Is Combined Ablation of Atrial Fibrillation Worthwhile? Isabella Bianco, 1 Gabriel Odozynski da Silva, 2 Alexander Romeno Janner Dal Forno, 2 Helcio Garcia Nascimento, 2 Andrei Lewandowski, 2 Elayne Pereira, 1 André d’Avila 2 Universidade do Sul de Santa Catarina, 1 Palhoça, SC - Brazil Hospital SOS Cardio, 2 Florianópolis, SC – Brazil Mailing Address: Isabella Bianco • Universidade do Sul de Santa Catarina - Avenida Pedra Branca, 25. Postal Code 88137-270, Palhoça, SC – Brazil E-mail: isabellabianco97@hotmail.com Manuscript received April 09, 2019, revised manuscript July 17, 2019, accepted July 17, 2019 DOI: https://doi.org/10.36660/abc.20190238 Abstract Background: Simultaneous ablation of atrial fibrillation (AF) and cavotricuspid isthmus (CTI)-dependent atrial flutter can be performed when both arrythmias had been recorded before the procedure. However, the best approach has not been defined in case of patients referred for ablation with CTI-dependent atrial flutter, without history of AF. Objectives: To assess the prevalence and to identify predictors of the first episode of AF after ablation of CTI-dependent atrial flutter in patients without history of AF. Methods: Retrospective cohort of patients with CTI-dependent atrial flutter without history of AF undergoing catheter ablation. Clinical characteristics were compared between patients who developed AF and those who did not have AF after the procedure. Significance level was set at 5%. In the analysis of predicting factors, the primary outcome was occurrence of AF after CTI-dependent atrial flutter ablation. Results: Of a total of 227 patients undergoing ablation of CTI-dependent atrial flutter (110 with history of AF and 33 without adequate follow-up), 84 were included, and 45 (53.6%) developed post-ablation AF. The HATCH and CHA2DS2- VASC scores were not different between the groups. Recurrence rate of CTI-dependent atrial flutter and complication rate were 11.5% and 1.2%, respectively, after ablation. Conclusions: Although ablation of CTI-dependent atrial flutter is a safe and effective procedure, 50% of the patients developed AF after the procedure. However, the role of combined ablation (CTI-dependent atrial flutter plus AF) aiming at preventing AF is still uncertain. (Arq Bras Cardiol. 2020; 114(5):775-782) Keywords: Arrhythmias, Cardiac; Atrial Flutter; Conduction; Radiofrequency Ablation; Isthmus Cavo-Tricuspid; Arial Fibrillation/prevention Introduction Cavotricuspid isthmus (CTI)-dependent atrial flutter is a common cardiac arrhythmia, safely and effectively treated by radiofrequency ablation with success and complication rates of 92-97% and 0.5-2.6%, 1-4 respectively. In this group of patients, those presenting atrial fibrillation (AF) before flutter ablation have an AF recurrence rate of 30-50% in the first 30 months 5,6 and of up to 82% in the following 90 months. 7,8 It has been suggested that AF and CTI-dependent atrial flutter are manifestations of the same atrial disease, and thus are associated with each other. For this reason, it has been advocated that patients with common atrial flutter, and history of AF, should benefit from simultaneous ablation of AF and atrial flutter during the first procedure, reducing the risk and costs of treatment when a second procedure is needed. The objective of our study was to assess the prevalence and to identify predictors of AF after ablation of CTI-dependent atrial flutter in a group of patients with no history of AF before flutter ablation. Ideally, if a risk profile for FA following CTI- dependent atrial flutter could be determined, a combined approach, including ablation of both arrhythmias, could be suggested in patients with atrial flutter and no history of AF. 6,9-11 Methods Study design and participants This was a cross-sectional study that evaluated patients of both sexes aged 18 years or older, undergoing ablation of CTI- dependent atrial flutter between 2017 and 2018 at SOS Cardio Hospital in the city of Florianopolis, Brazil, and at Institute of Cardiology of Santa Catarina in the city of São Jose, Brazil, with a follow-up of one year or longer, without history of AF 775