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'Near occlusion' of the carotid artery (NOCA) is not a well-defined entity. Recently, NOCA has been subclassified into two forms: 1) NOCA with collapse of the carotid artery, 2) NOCA without collapse. We aimed to compare the technical success and perioperative complication rates of these two sub-types to see whether there is a clinical correlate of this classification.

We retrospectively evaluated all patients with atherosclerotic extracranial carotid stenosis treated by carotid artery stenting (CAS) in a single medical institution between January 2014 and January 2018. Patients with NOCA were identified based on cerebral DSA findings. Patient demographics, presence of vessel collapse distal to the stenosis, technical success rate and perioperative (<=30 day) complication rate were analyzed.

We identified 59 NOCAs in 58 (46 male, 12 women) patients; one patient had bilateral NOCA. The mean age of patients was 67.4 (range 46 to 86) years. Twelve cases (20.3%) had NOCA with collapse and 47 cases (79.6%) had NOCA without collapse. The NOCAs were symptomatic in 42 cases (71.1%) and asymptomatic in 17 cases (28.8%). Fifty-eight of the 59 CAS procedures were successful. In one case of NOCA, we were not able to pass through the stenosis because of significant patient motion; the patient was advised to undergo stenting under general anesthesia but refused this procedure. The overall perioperative complications included hyperperfusion (HP; 8.6%) and minor stroke (1.7%). Compared to patients with NOCA but no collapse (4.2% of 47 cases), those with NOCA resulting in vascular collapse (27.2% of 11 cases stented) had significantly higher rates of post-intervention HP (Fisher's exact test, p=0.042). Permanent morbidity and mortality rate was 1.7% and 1.7%, respectively.

CAS is feasible in the setting of NOCAs with and without collapse. Care should be taken for HP risk, especially in the subgroup of patients with collapse.

Special care should be taken for HP in the treatment of NOCA by CAS