Invited commentary

Article Outline

• Copyright

One important disadvantage of endovascular aneurysm repair (EVAR) is the requirement for intense and lifelong surveillance. Dr Chaer et al have put this assumption to the test in a retrospective analysis of outcomes after EVAR in a selection of patients with a shrinking or stable aneurysm sac in whom follow-up was switched to color duplex ultrasound (CDU) imaging as the sole surveillance method. They conclude that CDU-only surveillance is safe in these patients and that it can be applied in almost all patients by 3 years postoperatively. There are several reasons why these conclusions must be interpreted with caution.

First, the reported safety is established in a highly selected group of patients who had been doing fine for 2 to 5 years under the previous (elaborate) follow-up protocol and after having been scrutinized and treated for endoleak: in short, successful EVAR patients.

Furthermore, the selection criteria for CDU-only surveillance were expanded after 1 year, skewing the study population. The early switchers were predominantly long-term successful Ancure (Guidant, Minneapolis, Minn) patients. Although this device is no longer commercially available, it was shown to lead to early and considerable sac shrinkage and to be durable. Conversely, the late switchers were the patients with the newer endografts—mainly Excluder (W. L. Gore and Assoc, Flagstaff, Ariz) and Zenith (Cook Inc, Bloomington, Ind)—and therefore had shorter follow-up after the switch. In fact, the Ancure contributes almost 2600 of the overall 4500 patient-months of follow-up after the switch compared with 550 months for the Excluder and 1200 months for the Zenith. Even more impressive is the difference in follow-up before the switch: around 4000 patient-months for Ancure, about 800 for Excluder, and 1000 for Zenith. So, the conclusion that CDU-only follow-up is safe mainly pertains to patients who can be considered successful EVAR cases >4 years after implantation of an Ancure endograft. There is relatively little evidence this is true for the other endografts.

With respect to the 97% “virtual” applicability at 3 years, I note that only half were actually switched to CDU-only. Extrapolation of safety may not be appropriate here.

It is not clear if endoleak should be the main objective of long-term EVAR follow-up. Many authors believe size is a more important indicator of failure, and CDU imaging has been shown to be less sensitive for size changes than computed tomography.

Finally, the authors make no mention of the value of plain abdominal films. This follow-up modality has many of the advantages of CDU imaging and also produces more objective results. Long-term concerns mainly pertain to device (metal or fabric) failures, and CDU imaging can only be expected to diagnose the consequences of these failures, whereas plain films might diagnose problems before consequences actually arise. Therefore, a follow-up protocol with both CDU imaging and plain abdominal films may even be safer than only CDU imaging, without many extra risks and costs.

Owing to the low incidence of treatment failure with the currently available endografts, large and long-term prospective studies are required to prove whether one can safely switch to a CDU-only follow-up policy, or even stop active surveillance entirely. With the described restrictions in mind, Dr Chaer and colleagues should be congratulated for their provocative and first-time report of outcomes of a minimized follow-up regimen.