Discussion

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Dr Todd Rassmussen (San Antonio, Tex). I thank you for the opportunity to review this and comment on the paper. I commend the authors for affording me the manuscript in advance and I enjoyed reading it and I congratulate the group from UT Southwestern on yet another clear, concise, neat, and germane manuscript. It was a good read and a nice presentation.

Because of the late hour, I won’t summarize the whole manuscript. I do, however, have a couple of specific questions and maybe you can clarify for me and the group. One pertains to the baseline similarity or dissimilarity potentially between the aneurysms compared in each of the three groups. As your group knows and has recently published, the characteristics of the aortic neck are very important in EVAR and yet in the manuscript there are no data on the neck anatomy between the three groups. No comparisons. There are no lengths. No diameters. No calcification scores. There is really no characterization of the necks in the three groups. And in the absence of this information, can the authors really be sure of that valid comparisons can be made between the three groups or among the three groups? In other words, were regression rates so favorable in the Medtronic group because the AneuRx grafts were placed in aneurysms with longer, less dilated necks, easier aneurysms, so to speak? Was there an incidence of graft migration at 1 year? Was there any incidence of Type I endoleaks in any of the groups?

The second and third questions really just pertain to clinical relevance and maybe put you on the spot with regards to your findings. Help us relate this to our practices. First of all, assuming these trends hold true in longer follow-up, what is their clinical relevance, would they impact your selection of grafts in the future? In other words, would you not use a specific graft because its rate of regression was 5% or 10% less than another graft at 1 year? Is it clinically relevant or are we just gilding the lily here?

And then lastly relates to the follow-up, which you mentioned, can we really make after EVAR—given what several groups around the country observed the expansion at 2 or 3 years—can we really make valid comparisons with only a 12-month follow-up? Again, I commend you on you paper. I think it has a lot of potential and you did a nice presentation.

Dr Harshal Broker. Thank you for those questions. To address your first question about the neck anatomy. We found that there were no differences between the aortic neck except that the Zenith graft was used in patients with larger necks, since this is the only graft currently available to treat necks greater than 28 mm; otherwise, there were no differences between the three groups. Again it should be noted that even with those who received the Zenith graft, there were no type I endoleaks and no evidence of type I endoleaks at 1 year. Furthermore, we found no differences between the groups with regard to type II endoleaks. So as far as we can tell, the aneurysm morphology between the three groups was fairly similar. The overall importance of sac shrinkage is unknown and how much is enough is uncertain. However, as an implanting physician, it is comfortable to know that the aneurysm is shrinking and it also comforts the patient as well. Certainly, it is important to follow these patients to see if these trends persist.

Unidentified speaker. I have two quick questions. There are pretty good data showing that volumetric analysis is more sensitive than actual size. Did you look at any volumetric data? And the second question, we have reported out of our core lab data that there is an endoleak influence on the rate of sac either expansion or regression amongst devices. Did you notice any difference when you looked at the influence of endoleak on sac regression or expansion in your study?

Dr Broker. As far as volumetric data, we did not look at that, but I think we do have the data to go back and look in this definite option to maybe strengthen the paper. In patients with type II endoleaks, there was still sac regression but it was significantly less than in those patients who did not have any endoleak. Because of the overall small number of patients with type II endoleak, we did not look at device specific outcomes in this regard.