Catheter ablation of atrial fibrillation using the Navx-/Ensite-system and a CT-/MRI-guided approach

Catheter ablation has become the first line of therapy in patients with symptomatic, recurrent, drug refractory atrial fibrillation. However, catheter ablation of atrial fibrillation is still a challenge. This is partially due to the high degree of variability with regard to the individual anatomy. Nevertheless, 3D imaging systems (CT, MRI) provide detailed information about the individual left atrial and pulmonary vein morphology. A 3D CT or MRI reconstruction of the left atrium can be displayed in the Navx-/Ensite-system in a synchronised way during the ablation procedure, thereby facilitating the intervention. This study summarizes our preliminary experience with different strategies of AF ablation using the Navx-/Ensite-system and a CT-/MRI-guided approach.

In a total of 41 patients, cardiac MRI (n = 7) or multi-detector spiral computed tomography (n = 34) was performed prior to an ablation procedure. Catheter ablation was performed for paroxysmal atrial fibrillation in 31 patients and for persistent atrial fibrillation in 10 patients. A 3D MRI or high resolution spiral CT data acquisition was performed and a surface rendered model of the LA was created. This model was displayed in the Navx-/Ensite-system throughout the ablation procedure.

Catheter ablation was performed using the Navx-system (n = 38) or the Ensite-system (n = 3). Three strategies were used depending on the type of atrial fibrillation: segmental isolation of the pulmonary veins (facilitated by a 3D real-time visualization of the ablation catheter and a circumferential mapping catheter; group A: 20 patients), linear lesions (group C: 3 patients) and a combined approach (group B; 18 patients). The CT-/MRI-models provided an excellent overview over the pulmonary veins and the left atrial appendage. They revealed a high degree of variability with regard to the individual anatomy (e.g. dimensions of the left atrial appendage, pulmonary vein ostia). The CT scans provided a more detailed reconstruction of the left atrial anatomy than the MRI scans (especially in patients who were in atrial fibrillation at the time of the data acquisition). In some patients, the CT-/MRI-models revealed a very small diameter of some pulmonary veins or side branches close to the ostium (e.g. right inferior pulmonary vein). Therefore, no attempt was made to achieve complete pulmonary vein isolation in some patients. In group A, 16/20 (80%) patients had no arrhythmia recurrence [mean follow-up 359 days (SD ± 317 days)]. Twelve out of eighteen (67%) patients in group B [mean follow-up 452 days (SD ± 311 days)] and 2/3 (67%) patients in group C did not experience an arrhythmia recurrence [mean follow-up 1,000 days (SD ± 34 days)]. There were no major complications.

The information derived from 3D CT- or MRI-reconstructions facilitates AF ablations performed with the Navx-/Ensite-mapping system and enhances the safety of these procedures.

Furthermore, the availability of an additional impedance-based 3D real-time visualization of the ablation catheter and the circular mapping catheter placed in the pulmonary veins represents a major advantage of the Navx system.