Serial monitoring of reverse left-atrial remodeling after pulmonary vein isolation in patients with atrial fibrillation: A magnetic resonance imaging study
Introduction
Pulmonary vein isolation (PVI) by radiofrequency percutaneous catheter ablation has been established as an important therapeutic alternative in patients with drug-refractory and symptomatic atrial fibrillation [1]. Importantly, atrial fibrillation is associated with atrial remodeling [2]: the hallmark of structural remodeling is atrial dilatation frequently accompanied by a change in atrial function [3]. Various studies using echocardiography [4], [5], [6], magnetic resonance imaging [7], [8] and computer tomography [9] demonstrated that restoration of sinus rhythm resulted in a reduction of left-atrial (LA) size. Two-dimensional transthoracic echocardiography is the most commonly employed method for determination of LA size with the aim to assist preprocedural planning and to determine reverse LA remodeling on follow-up examinations. However, left-atrial size needs to be calculated based on geometrical assumptions which may result in an insufficient estimate of LA size particularly in case of remodelled atria with asymmetric dilatation. Three-dimensional techniques inherently overcome these limitations and provide direct measurement of atrial volumes without underlying assumptions [10], [11], [12]. Consequently, functional cardiac magnetic resonance (CMR) based on steady state free precession imaging is increasingly gaining importance since it allows three-dimensional visualization of all cardiac cavities with consistently high endocardial border delineation [13], [14]. Thus, CMR imaging has the potential to accurately characterize the process of reverse atrial remodeling after pulmonary vein isolation by serial monitoring of left-atrial size and function based on three-dimensional volumetry.
Hence, the present study sought to prospectively determine the impact of sinus rhythm restoration on left-atrial volumes and function assessed serially by CMR imaging during the first year after pulmonary vein isolation in patients with paroxysmal or non-paroxysmal atrial fibrillation.
Section snippets
Subjects
Forty-one consecutive patients (28 men; age: 57 ± 10 years) referred for pulmonary vein isolation were prospectively enrolled. Pulmonary vein isolation was indicated if patients suffered from symptomatic paroxysmal or non-paroxysmal atrial fibrillation and medical treatment was regarded unsuccessful. Patients with normal left-ventricular ejection fraction but no valvular disease on transthoracic echocardiography were considered for study participation. Patients with known contraindications to CMR
Patient characteristics
Prior to the ablation procedure, paroxysmal atrial fibrillation was present in 25 patients (61%) and non-paroxysmal atrial fibrillation in 16 patients (39%). During the initial CMR examination 24 patients (59%) had regular sinus rhythm and 17 patients (41%) had atrial fibrillation. The pulmonary vein isolation procedure was completed in all 41 patients. The follow-up examinations at 1, 3, 6 and 12 months were missed by 3, 2, 7 and 2 patients, respectively, with each patient omitting one
Discussion
The present CMR imaging study prospectively assessed the impact of sinus rhythm restoration on reverse left-atrial remodeling using serial follow-up examinations during a 1-year period after pulmonary vein isolation. The main findings of the study are: [1] a significant and progressive decrease of left-atrial diastolic and systolic volumes occurred within one year after pulmonary vein isolation [2], successful restoration of sinus rhythm led to a significant decrease of LA diastolic and
Study limitations
At baseline CMR imaging 41% of patients had normofrequent atrial fibrillation and the irregular RR-interval length may have influenced the accuracy of LA volume assessment to some degree. However, many patients with atrial fibrillation exhibit diminished or absent active atrial contraction. Thus, in these cases the impact of arrhythmia on accuracy and reproducibility of LA volume measurements may be less relevant. The assessment of cardiac volumes and function using the disc summation method is
Conclusion
Pulmonary vein isolation based restoration of sinus rhythm led to a significant and progressive decrease of LA diastolic and systolic volumes during one year as assessed by direct volumetric CMR imaging. Hence, serial monitoring of LA volumes further corroborated the impact of sinus rhythm restoration and highlighted the temporal pathophysiological sequence of reverse left-atrial remodeling. Future studies with long-term follow-up exceeding the 12-month period may therefore be of interest.
Acknowledgement
The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology [22].
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