Distinct prognostic impacts of both atrial volumes on outcomes after radiofrequency ablation of nonvalvular atrial fibrillation: Three-dimensional imaging study using multidetector computed tomography
Introduction
Atrial fibrillation (AF) induces structural, histological and electrical remodeling of the atria and promotes the continuation of AF itself [1]. However, the majority of research has focused on left atrial (LA) disease; thus, LA is believed to play a key role in the initiation and continuation of AF. In contrast, the role of right atrial (RA) remodeling in the pathophysiology of AF has not been elucidated.
Recently, radiofrequency ablation (RFA) was shown to be a promising treatment strategy in selected AF patients [2]. However, even a successful RFA often fails to maintain sinus rhythm in a considerable number of patients; thus, predicting the outcomes of AF after successful RFA is of clinical importance. There are numerous predictors of AF recurrence after RFA, and recent studies have suggested the potential prognostic implication of the RA [3], [4]. Previously, using multidetector computed tomography (MDCT), we revealed that anatomical remodeling of RA was a determinant of early recurrence of AF after RFA (< 3 months after the index procedure), whereas LA volume was not [3]. Rather, the chronicity of AF, not RA and LA sizes, was an independent predictor of 1-year AF recurrence after the index RFA [3]. However, Akutsu et al. [4] reported that both atrial volumes are equally associated with AF recurrence after RFA and it is conflicting with the results of our previous study. Meanwhile, Shin et al. [5] suggested that LA alone, not RA size, was a predictor of AF recurrence after RFA in their investigation using echocardiography. Conceivable reasons for the discrepancy among those studies include differences in study sample, unidentical imaging modalities and various monitoring time windows. Moreover, those studies were limited by small sample sizes and low event rates, as mentioned by the authors of the papers. To verify the impact of both atrial volumes on outcomes of AF after index RFA, we sought to uncover the prognostic implications of both RA and LA volumes in a larger cohort.
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Study sample
The study protocol was approved by the Institutional Review Board of Yonsei University College of Medicine and complied with the Declaration of Helsinki. All patients provided written informed consent. All 242 patients with AF who underwent RFA were consecutively enrolled at Severance Cardiovascular Hospital between 2009 and 2012. No subjects in the current research had medical histories of more than mild valvular heart disease, cardiomyopathy, pericardial disease or cardiac congenital
Baseline characteristics
Patient characteristics are summarized in Table 1. The proportion of PeAF patients was 34%. Demographic findings were grossly similar between the PaAF and PeAF groups. On echocardiography, LV ejection fraction was lower (64 ± 7% vs. 62 ± 9%, P = 0.04) and LA anterior–posterior diameter was larger (40 ± 6 mm vs. 46 ± 6, P < 0.001) in PeAF patients.
Mean radiation dose for cardiac CT was 2.7 ± 1.6 mSv. Mean heart rate during cardiac CT was 63 ± 11 bpm and irregular heart rhythm during acquisition of cardiac CT was
Principal findings
The main findings of this study are: (1) both RA and LA volumes are larger in PeAF than in PaAF; (2) patients with larger RA and LA sizes have poor recurrence-free survival after RFA of AF; (3) failure of maintaining sinus rhythm after the index RFA was independently associated with the severity of LA enlargement in the overall AF cohort; (4) in PaAF patients, RA size might affect the outcome after RFA and be more important than LA size; and (5) in PeAF patients, LA size is more closely related
Sources of funding
This study was supported in part by research grants from Yonsei University College of Medicine (8-2011-0250, 7-2011-0758, 7-2011-0702, 7-2011-0015) and the Basic Science (20120007604) and National Research Program (2012045367) through the National Research Foundation of Korea, funded by the Ministry of Education, Science and Technology. This work was also supported by the Gachon University Gil Medical Center (Grant Number 2013-10).
Acknowledgments
The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology. We thank Kyu-Hyun Kim for his technical support.
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These authors contributed equally to this work.