Prognosis of Proximal and Distal Vertebrobasilar Artery Stent Placement

Abstract

Background and purpose: Vertebrobasilar artery stent placement (VBS) is potentially effective in preventing recurrent posterior circulation strokes; however, the incidences of in-stent restenosis and stented-territory ischemic events based on the location of stent placement have rarely been investigated. We aimed to investigate the characteristics and prognosis of VBS between intracranial and extracranial.

Materials and methods: This study was single-center retrospective cohort study, and we obtained medical records of patients who underwent VBS. We compared clinical and periprocedural factors between extracranial and intracranial VBS. The primary outcomes included the incidence of in-stent restenosis (>50% reduction in lumen diameter) and stented-territory ischemic events. We compared the incidence of in-stent restenosis and stented-territory ischemic events by using Kaplan-Meier curves.

Results: Of the 105 patients, 41 (39.0%) underwent extracranial VBS, and 64 (61.0%) underwent intracranial VBS. During the follow-up, the incidences of in-stent restenosis and stented-territory ischemic events were 15.2% and 22.9%, respectively. The procedure time was longer (47.7 ± 19.5 minutes versus 74.5 ± 35.2 minutes, P < .001), and the rate of residual stenosis (≥30%) just after VBS was higher (2 [4.9%] versus 24 [37.5%], P < .001) in intracranial VBS than in extracranial VBS. Also, the incidences of in-stent restenosis were significantly higher in intracranial VBS than in extracranial VBS (4.9% versus 21.9%, P = .037). On the other hand, the incidences of stented-territory ischemic events (7.3% versus 32.8%, P < .001) were significantly higher in intracranial VBS than in extracranial VBS. The main mechanisms of stroke were artery-to-artery embolism (2 [66.7%]) in extracranial VBS, and artery-to-artery embolism (9 [42.9%]) and branch atheromatous disease (8 [38.1%]) in intracranial VBS. The Kaplan-Meier curve demonstrated a higher incidence of in-stent restenosis and stented-territory ischemic events in intracranial VBS than in extracranial VBS (P = .008 and P = .002, respectively).

Conclusions: During the follow-up, the incidence of in-stent restenosis and stented-territory ischemic events was higher in patients with intracranial VBS than in those with extracranial VBS. The higher rates of postprocedural residual stenosis might have contributed to the increased risk of in-stent restenosis. Furthermore, prolonged procedure time and additional stroke mechanism, including branch atheromatous disease, might be associated with a higher risk of stented-territory ischemic events in intracranial VBS.

FIG 1.

Schematic diagram of the measurement of residual stenosis after stent placement (≥30%) and in-stent restenosis (>50%) during follow-up period. Residual stenosis after stent placement was defined as the remaining stenotic portion compared with the normal vessel diameter ([a-b]/a × 100). When (a-b)/a × 100 was larger than 30%, we considered it indicative of residual stenosis after stent placement. On the other hand, in-stent restenosis was defined as a stenosis of >50% when compared with the residual stenosis immediately following a procedure during the follow-up period ([b-c]/b × 100). When (b-c)/b × 100 was larger than 50%, we considered it as in-stent restenosis.

FIG 2.

Two illustrative patients. A, DSA (left image) revealed severe basilar artery stenosis. After procedure (middle image), severe stenosis of the basilar artery has improved. However, DWI (right image) showed bilateral medial pontine infarction after VBS. B, Patients with moderate vertebrobasilar artery stenosis (left image) had recurrent ischemic stroke in the posterior circulation. After procedure (middle image), moderate vertebrobasilar stenosis has improved. Follow-up DWI (right image) revealed multiple artery-to-artery infarction after VBS.

FIG 3.

Kaplan-Meier curves for in-stent restenosis and stented-territory ischemic events.