ABSTRACT
Near-occlusions were identified in the NASCET, because it is not possible to measure the degree of stenosis using the NASCET method in cases where the post-stenotic internal carotid artery (ICA) is narrowed or collapsed due to markedly reduced post-stenotic biood flow (16). Patients with ‘abnormal post-stenotic narrowing’ of the ICA were also identified in the ECST (17). In both trials, these patients had a paradoxically low risk of stroke on medical treatment (16,17). The low risk of stroke is most likely due to the presence of a good collateral circulation, which is visible on angiography in the vast majority of the patients with narrowing of the ICA distal to a severe stenosis (Fig. 3). The benefit from surgery in near-occlusions in the NASCET had been minimal,(16) and both the re-analysis of the ECST and the pooled analysis suggested no benefit at all in this group in terms of preventing stroke (9,10). Some patients with near-occlusion may still wish to undergo surgery, particularly if they experience recurrent TIAs. In the
Figure 2 The effect of endarterectomy on the 5-year risks of each of the main trial outcomes in patients with <30% stenosis, 30-49% stenosis, 50-69% stenosis, 70% stenosis without near-occlusion, and in near-occlusions, in an analysis of pooled data from the ECST, NASCET, and VA#309 trials (10).
