ABC | Volume 111, Nº6, December 2018

Original Article Odozynski et al PV anatomy and AF ablation Arq Bras Cardiol. 2018; 111(6):824-830 a 3D atrial model constructed during the procedure with an electroanatomic mapping system by (NavX®). Patients with persistent or long-term persistent AF, patients with previous ablations and AF of reversible etiology, hypertrophic cardiomyopathy, rheumatic heart disease, congenital heart disease and prior catheter ablation were excluded from the sample (Figure 1). Procedures and ablation protocol All procedures were performed under general anesthesia, orotracheal intubation, and invasive monitoring of blood pressure by radial or left femoral puncture, under the care of an anesthesiologist. Transseptal punctures were performed with echocardiography assistance, which was maintained throughout the procedure. All patients underwent circumferential isolation of the PVs through a 3.5-mm tip irrigated catheter ablation without contact force measurement, using radiofrequency energy with applications of up to 35 watts and 43°C for 30‑45 seconds, and demonstration of electrical VPs entrance and exit block in relation to the left atrium at the end of the isolation. After the demonstration of entrance and exit block, patients received 18 mg of IV adenosine bolus. In cases of electrical reconnection, new mapping-guided radiofrequency applications were performed until adenosine-mediated reconnection no longer occurred. The applications in the left atrium posterior wall were performed with 20 watts for up to 15 seconds, and were interrupted in case of increased esophageal temperature > 38°C. Applications to the left atrium posterior wall were monitored through an esophageal thermometer with multiple coated sensors (Circa®), and were stopped whenever there was a change in esophageal temperature above 38°C. During all procedures performed with an electroanatomical mapping system based on thoracic impedance (EnSite Navx - Abbott®), IV heparin bolus of 100mg/kg was performed, followed by continuous infusion to keep activated coagulation time between 350 and 450s. Definitions of anatomical variants of the pulmonary veins The vein anatomy was defined as normal when two right PV and two distinct left PV were viewed, and the presence of the left common trunk was defined when the two left PV coalesced on a path > 10 mm from before insertion into the left atrium in a common ostium (Figure 2). Clinical follow-up After the procedure, patients remained on antiarrhythmic drugs (propafenone, sotalol or amiodarone depending on the preference of the attending physician) for 1 month, and anticoagulant for at least 3 months regardless of CHA 2 DS 2 ‑VASc. There was a clinical follow-up of 1, 3, 6 and 12 months after the procedure with ECG and at least two continuous 5-day electrocardiographic (Holter) monitoring throughout the whole clinical follow-up. At the 10th week after ablation, patients were encouraged to undergo a 5-day Holter. Any atrial arrhythmia greater than 30 seconds duration documented after 1 month of blanking period indicated arrhythmia recurrence. 2 Symptoms severity before ablation and during any recurrences was characterized by the Canadian Cardiovascular Society Severity of Atrial Fibrillation (CCS-SAF) score, and the score of atrial fibrillation related symptoms of the European Heart Rhythm Association ( EHRA). 7 Statistical analysis Patient characteristics and procedures, recurrence rates after a single procedure, and complication rates were compared according to the groups: LCT (case) or non-LCT (control). The sample size was determined by a 1: 4 ratio for cases and controls with study power of 80%. Continuous variables were described as mean and standard deviation and compared using unpaired Student's t-test (two-tailed), respecting the criteria of normality by Shapiro-Wilk test. Categorical variables were described by absolute number and percentages in relation to the total sample, and were compared using the χ ² test or Fisher's exact test. The level of statistical significance adopted was 5%. Kaplan-Meier curve was used to evidence the relapse‑free rates over the follow-up time, and Log-Rank test was used to evaluate the difference between the groups (LCT x non-LCT). Statistical analysis was performed using IBM SPSS Statistics Editor software, version 22.0. Figure 1 – Flowchart study: patients undergoing ablation of AF categorized by presence of left trunk of the pulmonary veins. 266 patients undergoing AF ablation 172 patients included 30 LCT 142 n-LCT 94 excluded: – 5 long-term persistent AF – 36 persistent AF – 20 previous ablation – 33 minimum follow-up 825