ABC | Volume 110, Nº2, February 2018

Original Article Leiria et al Uninterrupted anticoagulants and flutter ablation Arq Bras Cardiol. 2018; 110(2):151-156 corresponded to ablation for AFL. Data collection counted on the present description of the electrophysiological reports and with information obtained in an electronic and physical chart. The patients who discontinued the follow-up at the hospital outpatient clinic were selected for a telephone interview, and their consent was registered by the listener. AFL was defined as a macro-reentrant atrial arrhythmia, electrocardiographically characterized by the presence of F-waves with constant morphology, and atrial frequency higher than 250 bpm. AFL typical was considered when the electrocardiogram (ECG) showed negative F-waves in derivations DII, DIII and VF, and positive in V1. 3 The parameters of the left ventricular ejection fraction (LVEF) and left atrial (LA) diameter were collected by the most recent echocardiogram found in the records, that had been conducted before ablation, which includes both transesophageal (TEE) and transthoracic (TTE) examinations. The ejection fraction was calculated using the methods of Teichholz or Simpson, according to the presence of segmental dysfunction. The atrial diameters were assessed using the M mode. The charts were revised aiming at recording the clinical information that was necessary for points in the score of CHA 2 DS 2 VASc (congestive heart failure, hypertension, age, diabetes, stroke, vascular disease, and female gender): sex, age, diagnosis of systemic arterial hypertension (SAH), diabetes mellitus (DM), congestive heart failure (CHF) or LVEF < 50%, peripheral vascular disease, myocardial infarction or aortic atherosclerosis and history of stroke or TIA. The referred diagnoses were defined according to previous publications. 10 Data of anticoagulation were registered before the ablation. The patients who were receiving the same medication in the four weeks prior to the procedure were considered as undergoing uninterrupted use: VKAs (warfarin and phenprocoumon), with international normalized ratio (INR) between 2 and 3.5, and NOACs (dabigatran, rivaroxaban and apixaban). All patients received the dosage of NOAC on the day before the procedure, in the morning or in the afternoon, at the assistant physician’s choice and according to the posology of the NOAC used (once or twice a day). None of the cases was performed with an interval higher than 24 hours after the administration of the daily use NOACs, or 12 hours after the ones with double dosage. The dose on the day of the ablation was instituted four hours after the removal of the introductory sheaths. The patients on VKA received the dose of the medication four hours after the removal of the introducers. The patients were followed-up at the outpatient clinic, and the first appointment was conducted from one to three months after ablation, through a clinical visit and 12-lead ECG. During the follow-up of these patients, we also included the data referring to emergency care or hospitalizations that took place in our institution. The patients who discontinued the follow-up at the outpatient clinic were selected for a telephone interview to clarify the following: • If they continued to use the anticoagulant; • If they presented an episode of stroke or TIA; • If they had any late complications related with the procedure. The Research Ethics Committee of our hospital approved the study protocol and we obtained a consent from all listeners for the performance of the interview. The study’s protocol n. is UP 5252/16. Outcomes We defined the following as main outcomes: the occurrence of hemorrhagic complication during the procedure; some examples are cardiac tamponade, bleeding that requires transfusion, bleeding with reduction of ten percentage points in the hematocrit, local vascular complication requiring intervention (major hemorrhagic events), and clinically uncomplicated hematomas (minor hemorrhagic event); adverse heart events were considered as a compound of all mortality causes, stroke, TIA, during follow-up. One specialist of each field validated each outcome. Exclusion criteria All patients with AFL submitted to a second procedure were excluded, as well as those with history of previous ablation at another service, those with left AFL and those who did not undergo the uninterrupted use of OAC in the peri‑procedural period. The patients using low-molecular- weight heparin (full anticoagulant dose or unfractionated heparin in continuous intravenous infusion, even if anticoagulated) were not included in this study. Statistical analysis The data were stored and analyzed with the Statistical Package for the Social Sciences (SPSS), version 22.0 (SPSS Inc., Chicago, IL, USA). The continuous variables were expressed as mean ± standard-deviation, and compared by the Student’s t test for independent samples. The categorical variables were expressed in percentage and compared using the χ 2 test. The variables were considered normal according to the observation of the central tendency measurements, kurtosis and asymmetry in the frequency histograms. The incidence density was calculated using the people-time interval for the occurrence of thromboembolic phenomena in the post‑ablation follow-up. This measure was carried out combining the number of people and the contribution of time during the study, and it was used as a denominator in the incidence rates. It was defined as the sum of individual units of time to which the people in the population studied were exposed, or at risk for the outcome of interest. The statistical significance level adopted was 5%. Results In the study period, there were 288 ablations per AFL. Of these, 154 were conducted with the uninterrupted use of oral anticoagulants, and these cases were included in the study. Figure 1 demonstrates the organization chart of inclusion of cases in the study. The mean age was 57.3 ± 13.1, and most were male (70%). The mean CHA 2 DS 2 -VASc was 2.1 ± 1.5 points, and 63% had a score higher than or equal to 2. Of the ablations, 98% were carried out with an 8 mm catheter – only 2% were conducted with an irrigated catheter. 152