Discussion

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Dr Hasan Dosluoglu (Buffalo, NY). In my practice, I have omitted the 1-month scan altogether if I am happy with the completion angiogram at the end of the procedure, because the studies show that most of these type 2 endoleaks, especially, will go away in 6 months. So why can't we do the exact reverse of what you did, and omit the first month CT and get the first one at 6 months and maybe go from there?

Dr Michael R. Go. Probably the most important reason to obtain the 1-month computed tomography (CT) is the 11% of patients who, in our hands, have an abnormality on that scan after EVAR. Almost all had no abnormalities on their completion angiograms. In fact, there were five type 1 endoleaks and one type 3 endoleak noted on 1-month scans in our study, all of which would require immediate intervention by today's standards.

Dr Keith Calligaro, (Philadelphia, Pa). A comment and a question. I think that in your last slide, the conclusion should be that a CT scan is not necessary at 6 months for Ancure grafts. The vast majority of your grafts were Ancure, and the remaining numbers were so small, I don't know if you can make that conclusion about those other type of grafts. My question is whether you are still doing CT scans as follow-up? We've stopped doing routine CT scans and just do duplex scan surveillance. If the first CT scan is normal, we will follow up with duplex scans only, unless a problem shows up.

Dr Go. There were a significant number of patients who did not have Ancure grafts, 63% in group I. But you are right, that number was only 26% in group II. And as we find out more and more that EVAR outcomes, and probably complications, are device-specific, your point is well taken. The frequency of positive findings at 1 month is equivalent, which would allow us to extend the recommendations to all grafts. As you mention, we agree that duplex can be substituted for CT once the aneurysm fails to expand; this requires a couple of CT scans and does not apply necessarily to the first year of follow-up, which is the focus of this paper. Our current policy is similar to yours.

Dr Clifford Buckley (Temple, Tex). We have come to the same conclusion. We have reviewed 4-year follow-up of 424 patients between our own institution and the UT Southwestern in Dallas, using a combined database. The distribution of the grafts was fairly equal between all of the four major players—Cook, Medtronic, Gore, and Ancure. The number of abnormal findings in patients who had one normal CT scan was extremely low. The number of interventions that were required was extremely low. It made us look at whether we were gaining anything at all from the intensity of the follow-up. It appears that we gained very little. Most of the patients who required an intervention came for an unscheduled evaluation with new symptoms. If they had aneurysm sac enlargement, they came in with complaints of abdominal pain or back pain. People who had graft limb occlusions came in because they had new onset claudication. The routine surveillance yielded very little information affecting patient care.

Dr Go. That is similar to our findings here. However, our current data only apply to the first year of follow-up and cannot be extrapolated to late follow-up, where a small number of patients still present with asymptomatic findings requiring treatment.

Dr Mark Fillinger (Lebanon, NH). I appreciate your paper and it was a nice study. I think I agree with your conclusions, but I just wanted to sound a couple notes of caution. One was your conclusion that the 6-month was of no value, period. But actually what you showed was there was no value if you had a normal 1-month CT, which was the majority of the patients.

The other caution is using “no change in diameter” as your criteria for “no problems.” If you look at the Gore Pivotal Clinical trial, the vast majority of patients had no enlargement at 1 year by diameter, and yet we now know that over a third of them were already enlarging by volume at that point. So you have to be cautious about using an insensitive parameter to declare that there is no present or future problem.

Dr Go. We agree that the 6-month CT is of little significance only when the 1-month CT is normal. Since a 1-year CT is still in our algorithm and we use a significant change of 5 mm in diameter as our threshold, we do not see the utility of a more sensitive longitudinal parameter.

Dr Roger Greenhalgh (London, United Kingdom). I thought the paper was a very useful contribution, and the information given us about the 6-month CT scan is a very helpful piece in the jigsaw. I think it is important to put this into perspective. We have gone through an era of the trials and during this decade of the trials, we have had to adopt a very, very careful attitude to this then new technique. CT scan was the agreed method of checking and during the trial period, we got used to using CT scans, frequently at first and annually.

I think we are moving away from the early experience, and it then becomes relevant to look at different health systems in the different parts of the world. The issue that you do not have in the United States to the same extent as in certain parts of Europe and Scandinavia and Britain with their National Health Service is this irritating matter of cost-effectiveness. Cost-effectiveness is something that our governments and the authorities will take into account and they will measure the benefit of EVAR against the various drawbacks against that benefit. One of the most important costs is the CT scan. An annual CT scan would seem to be high priority to lose in the follow-up for cost-effectiveness to have any hope of success. That is the background for my question.

But my question is, can you examine your data to look and see if you could, in retrospect, have done without your annual, 1-year CT scan? Could you have used other modalities to find those issues reliably without CT scan? Because if you can, that will be the beginning of a potential cost-effective future for EVAR.

Dr Go. Certainly, any advantage of EVAR over open repair in terms of cost-effectiveness is abrogated in the long-term by the need for this ongoing surveillance. Thus, we have been moving toward ultrasound surveillance. It would be possible to reanalyze our database beyond 1 year, and this is one of the next steps in our ongoing effort at University of Pittsburgh to pare down the surveillance regimen.

Dr Alan B. Lumsden (Houston, Tex). I think one of the exciting opportunities in imaging is that all of the new systems which we're installing will do fluoro-CT. We are going to have the opportunity in an operating room after the anticoagulation is reversed to do our own CT scans. And the question then is, we may not need a follow-up CT scan for 2 or 3 years, but it is going to put CT scanning in the operating room, basically, under a certain semblance of control of the surgeons.