International Circulation: Does circumferential pulmonary vein (PV) isolation guided by image integration improve the procedural and clinical outcomes of atrial fibrillation (AF) ablation in comparison with segmental PV isolation and circumferential PV isolation guided by three-dimensional (3D) electroanatomical mapping alone，and why?

　　《国际循环》：与单独应用3维电生理标测系统引导的部分肺静脉消融和环肺静脉消融治疗房颤相比，是否图像整合标测引导下的环肺静脉消融改善了消融程序及临床预后，为什么?

　　Roberto De Ponti: In my experience， image integration has been essential in guiding this kind of ablation because in the majority of cases you may have different anatomical variations of the pulmonary veins. Therefore you can never be sure of where you are based only on fluoroscopy. The 3D imaging of the CT scan integrated into electroanatomical mapping is quite essential to guide this kind of ablation. In my opinion it renders the procedure easier and， in our center， also more effective for circumferential pulmonary vein ablation. However， if you look at the literature there are conflicting data. Some data are in favor of the fact that you can improve the outcome of the procedure by using this kind of ablation strategy. In other cases no data show that you have a decrease in the fluoroscopy time and in the procedure time. We have just published in the August issue of EUROPACE our experience of the Italian registry， where we compared the procedure of circumferential pulmonary vein ablation guided only by the CartoXP technology with the procedure guided by CartoMerge. On the medium-term follow-up， those patients who underwent the procedure on the Cardomerge guidance had a significantly better outcome in terms of recurrence after the ablation. We couldn’t demonstrate that there was a decrease in the procedure time nor in the fluoroscopy time. But I do think that what we were able to achieve was a good result . In that registry we were able to include more than 500 patients treated over no more than a couple of years.

　　International Circulation: Which imaging integration do you think is better， CT or MRI?

　　Roberto De Ponti: This has been debated a little bit. MRI spares a lot of radiation exposure whereas CT doesn’t spare radiation exposure but in our experience does provide better imaging of the pulmonary vein vessels. In our experience， if you optimize acquisition of the CT scan by not using the ECG-gated modality but just the non-gated modality， you are able to spare a lot of radiation exposure. Our average radiation exposure goes from 23 mSv to only 3mSv. I think this is the best way to provide nice imagining with very low radiation exposure.