ABC | Volume 111, Nº6, December 2018

Original Article Odozynski et al PV anatomy and AF ablation Arq Bras Cardiol. 2018; 111(6):824-830 Figure 3 – Kaplan-Meier curves for AF relapse after catheter ablation categorized by the presence of the left common trunk of the pulmonary veins; Log-rank test for comparison of recurrence curves between groups (LCT x n-LCT). p-value = 0.04. AF: atrial fibrillation; PV: pulmonary veins. 100% 90% 80% 70% 60% 50% Recurrence in AF ablation by presence of PV left common trunk non-LCT LCT 90% 73% 0 9 18 27 36 Time (months) Freedom from AF recurrence rate (%) 24-hour Holters, and even coronary angiography with the intention of diagnosing a possible trigger for AF. Infrequently, however, these patients undergo heart CT/MRI that, if properly performed, could define the pulmonary venous anatomy and assist in the clinical decision facilitating the indication of catheter ablation. Our study is not aligned with evidence that the presence of PVs anatomical variations (number and disposition) would be associated with a higher and more advanced degree of atrial remodeling from the electrical and structural point of view and, consequently, worse post-ablation outcome. 4,14,15 In our results, the relapse rate in the LCT group was 3 times lower than in the non-LCT group, with patients’ clinical characteristics being similar and homogeneous in all analyzes. From the technical point of view, the presence of LCT facilitates the manipulation and the contact of the ablation catheter in the left atrium. The simpler the manipulation, the better the contact with the region to be ablated. Recent studies have shown that the tissue-to-contact relationship during ablation is crucial for lesion formation and is linked to better outcomes. 16 Therefore, efficient tissue contact presumes a greater energy delivery through radiofrequency and formation of a more stable and homogeneous scar, 17 which would ultimately result in a longer lasting isolation of PVs. That way, other studies using cryoablation also presented a more favorable result in patients with LCT. In cryoablation studies, however, the presence of LCT was not related to a more satisfactory outcome when compared to patients without the structure. 18 Limitations The objective of this study was to describe the clinical characteristics and efficacy and safety outcomes in patients undergoing catheter ablation in the treatment of AF. This is a case-control study and, certainly, there are limitations. First, the sample size is small and may not be sufficient to detect differences between the two groups, particularly because of the low prevalence of LCT. Second, the presence of observation bias is recognized, since PVs anatomy is revealed during the procedure. Third, no detailed tool was used to assess symptoms in the presence of AF, but rather CCS-SAF and the EHRA score, which are generic scales for symptomatic evaluation. Despite this, the study provides an interesting perspective on the invasive treatment of AF in patients with LCT. Conclusion In our sample, patients with LCT who underwent the first catheter ablation procedure to treat PAF presented a lower rate of relapse compared to patients without this anatomical alteration. The research on LCT should be incorporated to the investigation of PAF patients because ablation is more effective in this group of patients. Author contributions Conception and design of the research, Acquisition of data, Critical revision of the manuscript for intellectual contente and Analysis and interpretation of the data: Odozynski G, Dal Forno ARJ, Lewandowski A, d'Avila A; 828