Development of the Circle of Willis Score (COWS) to help guide decision making during acute tandem occlusion treatment: Preliminary analysis.

Background: Acute tandem occlusions (TOs) are challenging to treat. Although acute carotid stenting of the proximal lesion is well tolerated, there are certain situations when the practitioner may be wary of acute stenting (bleeding concerns).

Objective: The purpose of this study was to retrospectively study patients with tandem occlusions who had re-occlusion of the extracranial ICA and develop a Circle of Willis Score (COWS) to help predict which patients could forego acute stenting.

Methods: This is a retrospective review of TO patients with a persistent proximal occlusion following intervention (either expected or unexpected). Pre intervention CTA and intraoperative DSA were reviewed, and each patient was assigned a score 2 (complete COW), 1a (patent A1-Acomm-A1), 1p (patent Pcomm), or 0 (incomplete COW). Findings from the DSA took precedence over the CTA. Two cohorts were created, the complete COW cohort (COWS 2) versus the incomplete COW cohort (COWS 1a,1p, or 0). Angiographic outcomes were assessed using the mTICI score (2b-3) and clinical outcomes were assessed using discharge mRS (good outcome mRS 0-3).

Results: Of 68 TO cases, 12 had persistent proximal occlusions. There were 5/12 (42 %) patients in the complete COW cohort, and 7/12 (58 %) in the incomplete COW cohort (5/12 with scores of 1a/1p and 2/12 with a score of 0). In the complete COW cohort, there were 2 ICA-ICA and 3 ICA-MCA occlusions. In the incomplete COW cohort, there was one ICA-ICA occlusion and 6 ICA-MCA occlusions. LKW-puncture was shorter in the complete COW cohort (208 min vs. 464 min, p = 0.16). Successful reperfusion was higher in the complete COW cohort (100 % vs. 71 %). There was a trend toward better clinical outcomes in the complete COW cohort (80 % vs 29 %, p = 0.079).

Conclusion: The COWS is a simple score that may help predict a successful clinical outcome without proximal revascularization when concerned about performing an acute carotid stent during TO treatment. Evaluation in larger TO cohort is warranted.