Although different diagnostic tools and criteria were chosen to determine the presence of an ISR, the incidence is surprisingly constant throughout most of the publications under review. The rate of moderate (≥50%) and high-grade ISR (≥70%) varies between 6.7–13.9% and 2.7–6.3%, respectively (see Table 1). Notably, this rate is higher as compared to those with a preceding CEA treatment within some of the randomised trials [16] and [42], which has led to a keen discussion on the long-term durability of a CAS procedure [10]. Against the background that

there is no established treatment learn more standard for patients with an ISR, this should be considered before a CAS intervention is recommended as the preferred treatment modality. The surgical treatment of an ISR remains an exception since it is technically demanding and might be associated with periprocedural complications [43]. In most of the cases, a redo-PTA or CAS is currently performed

after Natural Product Library datasheet ISR, which seems to be associated with an acceptable rate of periprocedural complications [29], [30] and [35]. As a method of first choice to diagnose ISR, preferably a non-invasive technique should be chosen to avoid a potential harm for the patient during the essential long-term follow-up. In this context, serial duplex ultrasound investigations seem to best fulfil the requirements for long-term follow-up and have been used in all studies retrieved for the current review. As a secondary validation method, high-grade ISR could be confirmed by CT angiography Sodium butyrate in some selected cases. Since duplex ultrasound has turned out to lead to a reliable ISR diagnosis whereas conventional angiography is

known to be an invasive procedure possibly linked with potentially dangerous complications such as stroke or bleedings, a conventional angiography should only be considered in those patients with a symptomatic or high-grade ISR, who are likely to be treated afterwards or within the same angiographic session. A fact which could reduce the value of duplex ultrasound as a first choice method for serial follow-up investigations is the generally lacking agreement of exact ultrasound criteria to grade an ISR. Considering the peak systolic velocity (PSV) as the most commonly used duplex criterion, a considerable distribution of cut-off values could be observed. For example, the cut-off PSV for the diagnosis of an ISR of ≥50% varied from ≥140 cm/s in one study [19], over a PSV ≥ 175 cm/s in the publication of Setacci et al. [25] and a PSV ≥ 220 cm/s in the study by Cosottini et al. [28] up to a PSV ≥ 224 cm/s by AbuRahma et al. [24]. Despite the fact that ultrasound criteria have to be adapted to each local high quality ultrasound laboratory, the wide range of values between the studies urges the need for an implementation of generally valid ultrasound criteria in ISR diagnosis [12] and [13].