ABC | Volume 114, Nº5, May 2020

Original Article Bianco et al. Ablation of atrial flutter and fibrillation Arq Bras Cardiol. 2020; 114(5):775-782 investigating the benefits of combined procedures in patients without history of AF are needed. 19 It is worth highlighting that the choice for the combined therapy is always made for patients with CTI-dependent atrial flutter and history of AF. Predicting factor for AF In the present study, none of the variables or scores analyzed was able to predict the occurrence of AF after ablation of CTI-dependent atrial flutter in the study population. The literature about predictors for the occurrence of AF is inconclusive. Different studies have described clinical variables such as comorbidities, previous history of AF, duration of atrial flutter, 20 echocardiographic and electrocardiographic variables as predictors of AF. 6,10,21-23 On the other hand, Chinitz et al., 5 in a study with 254 patients undergoing ablation of CTI- dependent atrial flutter, followed-up for a mean of 30 ± 22 months, did not find any predictors for AF, even among those more commonly associated with arrhythmia, corroborating our findings. The HATCH score has been proposed to predict the progression of AF from paroxysmal to persistent AF. In sub- analyses, the HATCH was useful in predicting the occurrence of AF in asymptomatic patients. In our analysis, no difference was observed between the groups in the occurrence of AF after ablation of CTI-dependent atrial flutter according to the HATCH score. 24 In addiction to predicting the risk of stroke in patients with AF, the CHA 2 DS 2 -VASC score is known to be used for prediction of morbidity and mortality in different clinical settings. However, in the present study, the score did not show statistically significance in predicting AF after ablation CTI-dependent atrial flutter. Limitations The first limitation of the study is its retrospective nature. Second, the limited sample size may have prevented the detection of significant differences between the two groups (AF vs. non-AF) and identify predicting variables of AF after invasive treatment for CTI-dependent atrial flutter. Finally, we did not monitor asymptomatic arrythmias after ablation of CTI-dependent atrial flutter, and hence the real incidence of AF may have been underestimated. Conclusions In our study, ablation of CTI-dependent atrial flutter was an effective and safe procedure. There was a high incidence of AF after the ablation procedure, even in patients without history of AF, and regardless of clinical characteristics of the patients. There is not enough evidence to recommend combined ablation for treatment of atrial flutter aiming at preventing the occurrence of AF. Studies with longer follow up are needed to determine the real benefits of simultaneous ablation. Author contributions Conception and design of the research: Bianco I, Silva GO, Pereira E, d’Avila A; Acquisition of data and obtaining financing: Bianco I; Analysis and interpretation of the data: Bianco I, Silva GO, d’Avila A; Statistical analysis: Bianco I, Silva GO; Writing of the manuscript: Bianco I, Pereira E, d’Avila A; Critical revision of the manuscript for intellectual content: Bianco I, Silva GO, Dal Forno ARJ, Nascimento HG, Lewandowski A, Pereira E, d’Avila A. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding This study was funded by Programa Unisul de Iniciação Científica. Study Association This study is not associated with any thesis or dissertation work. Ethics approval and consent to participate This study was approved by the Ethics Committee of the Unisul under the protocol number 2.412.219. All the procedures in this study were in accordance with the 1975 Helsinki Declaration, updated in 2013. 781