Acquisition of the pulmonary venous and left atrial anatomy with non-contrast-enhanced MRI for catheter ablation of atrial fibrillation: Usefulness of two-dimensional balanced steady-state free precession

Background: Usually, the pulmonary venous and left atrial (PV–LA) anatomy is assessed with contrast-enhanced computed tomographic imaging for catheter ablation of atrial fibrillation (AF). A non-contrast-enhanced magnetic resonance (MR) imaging method has not been established. Three-dimensional balanced steady-state free precession (3D b-SSFP) sequences cannot visualize the PV–LA anatomy simultaneously because of the signal intensity defect of pulmonary veins. We compared two-dimensional (2D) b-SSFP sequences with 3D b-SSFP sequences in depicting the PV–LA anatomy with non-contrast-enhanced MR imaging for AF ablation. Methods: Eleven healthy volunteers underwent non-contrast-enhanced MR imaging with 3D b-SSFP and 2D b-SSFP sequences. The MR images were reconstructed on the 3D PV–LA surface image. Two experienced radiological technicians independently scored the multiplanar reformatted (MPR) images on a scale of 1–4 (from 1, not visualized, to 4, excellent definition). The overall score was a sum of 5 segments (LA and 4 PVs). Results: In the 2D b-SSFP method, MR imaging was successfully performed, and the 3D PV–LA surface image was precisely reconstructed in all healthy volunteers. The image score was significantly higher in the 2D b-SSFP method compared to the 3D b-SSFP method (19 [19; 20] vs. 12 [11; 15], p=0.004, for both observers). No PV signal intensity defects occurred in the 2D b-SSFP method. Conclusions: The 2D b-SSFP sequence was more useful than the 3D b-SSFP sequence in adequately depicting the PV–LA anatomy

Visualizing radiofrequency lesions using delayed-enhancement magnetic resonance imaging in patients with atrial fibrillation: A modification of the method used by the University of Utah group

Background: Atrial tissue fibrosis has previously been identified using delayed-enhancement MRI (DE-MRI) in patients with atrial fibrillation (AF). Although the clinical importance of DE-MRI is well recognized, the visualization of atrial fibrosis and radiofrequency (RF) lesions has still not been achieved in Japan, primarily because of the differences in contrast agents, volume-rendering tools, and technical experience. The objective of this study was to visualize RF lesions by using commercially available tools. Methods: DE-MRI was performed in 15 patients who had undergone AF ablation (age, 59±4 years, left atrium diameter, 40±2 mm). Specific parameters for MR scanning obtained from previous reports were modified. Results: Of the 15 images, the images of three patients were uninterpretable owing to low image quality. RF lesions could be visualized in 8 (67%) of the 12 patients. Conclusions: In the current study, we successfully demonstrated that RF lesions could be visualized in Japanese patients using DE-MRI, although only commercially available tools were used

Incidence of esophageal injury after pulmonary vein isolation in patients with a low body mass index and esophageal temperature monitoring at a 39 °C setting

Background: Esophageal injury following catheter ablation of atrial fibrillation (AF) is reported to occur in 35% of patients. Even with a low energy setting (20–25 W), lesions develop in 10% of patients. Body mass index (BMI) has been reported to be a predictor of esophageal injury, indicating that patients with a low BMI (<24.9 kg/m2) are at a higher risk. We hypothesized that catheter ablation with a lower energy setting of 20 W controlled by esophageal temperature monitoring (ETM) at 39 °C could prevent esophageal injury even in patients with a BMI <24.9 kg/m2. Methods: Twenty patients with AF were included (age, 63±8 years; BMI, 22.9±1.3 kg/m2, left atrium diameter, 44±11 mm). If the esophageal temperature probe registered a temperature of >39 °C, radiofrequency (RF) application was stopped immediately. RF application could be performed in a “point by point” manner for a maximum of 20 s. Endoscopy was performed 1–5 days after ablation. Results: Esophageal mucosal injury was not observed in any patient in the study. Conclusions: Catheter ablation using ETM reduced the incidence of esophageal injuries, even in patients with a low BMI