Objective: 
To report and compare the degree of intracranial carotid artery calcification (ICAC), procedural and clinical outcomes of patients with intracranial atherosclerosis-related occlusions (ICAS-O) treated with thrombectomy.

Methods:
 The clinical characteristics, imaging, and thrombectomy outcomes of ICAS-O and non-ICAS-O patients were analysed from our prospective database. ICAC was determined on the non-contrast CT at presentation, using the Woodcock scale which assessed the thickness and severity of calcification. Patients were treated with an aspiration-first approach, and stent-retriever was used as rescue when required. Stenting and angioplasty of the stenotic vessel was performed if there was early re-occlusion after thrombectomy.

Results: 
Between 2006 to May 2017, 64 consecutive patients treated with endovascular thrombectomy for acute large vessel occlusion stroke were included. The mean age was 63.4 years (range 20-92) and 98.4% were ethnic Chinese. 14.1% were ICAS-O. The mean Woodcock scale for ICAC was significantly higher in the ICAS-O group compared to non-ICAS-O (2.8 vs 1.6, p=0.044). There were no significant difference in the rate of successful reperfusion (defined as TICI2b/3), functional independence at 90 days, and mortality between groups. ICAS-O was associated with significantly higher need of rescue therapy with stent –retriever (55.6% vs 5.5%, p=0.001) and adjuvant stenting and angioplasty due to early reocclusion (33.3% vs 0%, p=0.002). 

Conclusion: 
The severity of ICAC may be correlated with ICAS-O in thrombectomy patients. Compared with other stroke etiologies, ICAS-O was associated with a higher need of stent-retriever rescue, adjuvant stenting and angioplasty, but clinical outcomes were similar.

Endovascular thrombectomy for occlusions due to intracranial atherosclerosis: correlation with intracranial carotid artery calcification and treatment implications