How to treat recurrent renal artery instent restenosis? Editorial comment on treatment of reoccuring instent restenosis following reintervention after stent‐supported renal artery angioplasty–Article by Zeller et al.

Treatment of instent restenosis remains one of the major drawbacks of endovascular stenting in almost all vessel areas. Different strategies have been proven effective with respect to immediate angiographic results, however, reported intermediate and long term data are scarce and disappointing for most vessel areas. Fortunately, in renal arteries of 6 mm in diameter restenosis rarely occurs [1], but restenosis rather frequently is encountered after stenting of small arteries and long lesions. Zeller et al. [2] reported their vast experience with renal stenting in several publications and in this issue of the Journal present a series of 33 patients treated for recurrent renal instent restenosis. Repeat balloon angioplasty, bare metal stenting, drug eluting stents, stent graft implantation, and cutting balloon angioplasty were used to resolve the recurrent renal instent restenosis with variable success. The authors conclude from their series that drug-eluting stents and stent grafts yielded the best results with no further occurrence of restenosis during follow-up, whereas balloon angioplasty and bare stents had intermediate results. Cutting balloon angioplasty unexpectedly showed the worst results. Importantly, numbers within the different subgroups are quite small and, therefore, results have to be interpreted with caution. Nevertheless, the observed effects with the different treatment options seem to reflect what can be expected from pathophysiological assumptions on the behavior of instent neointimal hyperplasia: patients with repeat instent restenosis seem to represent a selection of individuals prone to excessive and progressive neointimal hyperplasia, who likely will exhibit ongoing restenosis unless the proliferative process is stopped. Therefore, additional measures rather than just redilating a critical restenosis are needed to prevent recurrent failure. Nevertheless, in patients with a first restenosis-repeat balloon angioplasty with secondary restenting on indication in case of an unacceptable result seems to be the treatment of choice. To resolve the problem of repeated recurrent restenosis, on the one hand, purely mechanical measures like stentgrafts or cutting balloon are available, and on the other hand, combined pharmacological and mechanical strategies, namely coronary drug eluting stents, can be used to handle this problem. From a personal perspective the use of drug eluting stents is favored, as it is technically straight forward and based on the results of the sirolimus eluting stent arm of the GREAT study [Sapoval et al., unpublished results] in de novo lesions safety of this approach has been demonstrated in renal arteries. Furthermore, the elution of an antiproliferative drug likely may stop the ongoing process of neointimal hyperplasia. Unfortunately, the use of drug eluting stents is limited by the diameter of the artery, as current devices can be postdilated only to a maximum of around 4.0–4.5 mm. In larger arteries with repeated restenosis, stent graft implantation may be an alternative as reported by Zeller et al. [2]. However, one has to be aware that the midterm and long-term experience with these devices is very limited, and poor results have been encountered in coronary arteries [3] and in the carotid territory [4] with certain products. Finally, cutting balloon angioplasty was used in three patients included in the current study, and all three patients developed an early restenosis. Disappointingly, the concept of controlled incision and less traumatic dilatation does not prove to be effective in renal instent restenosis, as it was ineffective in coronary restenosis [5]. In conclusion, the experience reported by Zeller et al. [2] seems useful in clinical practice, and based on these findings, further systematic evaluation of drug