Abstract 1916: Anatomic Relationship of the Left Atrium and the Esophagus in Patients Undergoing Catheter Ablation of Atrial Fibrillation
Background: Left atrio-esophageal fistula has been reported as a rare but life-threatening complication of atrial fibrillation (AF) ablation. The purpose of this study was to describe the topographic anatomy of the posterior left atrial (LA) and the esophagus by means of multidetector computed tomography (MDCT) for minimize the risk of esophageal injury during AF ablation.
Methods: MDCT was performed in consecutive 110 patients (mean age: 57 ± 9 years, 21 female) with paroxymal or persistent AF before an ablation procedure. Consecutive axial and sagital section of the CT scan were examined to determine the relationship, size, and thickness of the tissue layers between posterior LA and esophagus.
Results: Two major types of esophagus routes were demonstrated. Type A routes were found in 90% (99/110) patients with the lower portion of esophagus close to the ostium of the left inferior pulmonary vein (LIPV). Type B routes were found in 10% (11/110) patients with the lower portion of esophagus close to the ostium of the right inferior pulmonary vein (RIPV). LA sizes significantly differed between type A and type B (A: 42.3 ± 5.5 mm vs B: 36.7 ± 6.3 mm, P= 0.02). The shortest distance between descending aorta and the posterior LA aspect was significant closer in type B than type A (A:3.9 ± 1.8 vs B:2.2 ± 0.9 mm, P = 0.02). The mean thicknesses of the anterior esophageal and posterior LA walls were 2.1 ± 0.7 mm and 1.3 ± 0.3 mm. In 93% (102/110) of patients, there was an identifiable fat pad between the esophagus and the posterior LA. The thickness of the fat pad was significant thinner in larger LA size [> 42mm, mean: 46 ± 3 mm] than normal LA size [mean: 37 ± 4 mm] (1.2 ± 0.6 vs 1.6 ± 0.9 mm, P = 0.04).
Conclusions: There were marked variations in the anatomic relationship of the posterior LA and esophagus. In large LA patient, the fad pad between LIPV and esophagus to protect the esophagus from the direct thermal injury became thinner by stretching effect of enlarged LA. Visualization of anatomic relationship by MDCT before ablation procedure is important for deciding the location of the ablation lesions and avoiding the potential risk of esophageal injury.