Elena Zapata-Arriaza, MD

Broocks G, Kniep H, Schramm P, Hanning U, Flottmann F, Faizy T, et al. Patients with low Alberta Stroke Program Early CT Score (ASPECTS) but good collaterals benefit from endovascular recanalization. J Neurointerv Surg. 2019.

The primary therapeutic target of mechanical thrombectomy defined by the salvageable tissue at risk is minimized in patients with low Alberta Stroke Program Early CT Score (ASPECTS). In contrast, the risk of developing malignant infarctions is maximized in patients with a large early ischemic core, which can lead to severe complications by progressive ischemic edema within the first days after stroke onset. Low ASPECTS (≤5) still represents a limitation for stroke thrombectomy performance. But what happens in those patients with low ASPECTS and good collaterals after endovascular treatment? Do these cases have the potential to achieve good functional results? Broocks and colleagues have employed these questions as the starting point in the present paper.

Between October 2015 and December 2018, ischemic stroke patients with large vessel occlusion (LVO) in the anterior circulation and an ASPECTS ≤5 were analyzed. In addition, collateral status was assessed in CT angiography for all included patients. Good clinical outcome was defined as mRS 0-3. Patients were dichotomized by vessel recanalization status ( TICI 2b-3; successful recanalization and TICI 0-2a; failed recanalization).

One hundred patients achieved inclusion criteria, but endovascular recanalization was attempted in 74 patients, with TICI 2b-3 rate of 68%. The main finding of the study was that despite low ASPECTS, vessel recanalization with good collateral status and younger patient age were independent predictors of improved functional outcome. Furthermore, in patients with TICI 2b-3, collateral status was the only independent predictor of good functional outcome. Mentioned good collateral status increased 12% the probability for good outcome in patients without vessel recanalization and 47.5% in patients with vessel recanalization.

Up to 30% of patients with low ASPECTS may have good collateral status. According to the results described, the use of collaterals as a support element in patients with low ASPECTS could increase the number of thrombectomy candidates. However, the goal is not the quantity but the quality of mechanical thrombectomy in terms of functional outcome results of those patients with LVO stroke. It is possible that when we have an elderly patient, and a low ASPECTS, the balance leans towards conservative management. However, in younger patients, we look for all possible support elements to indicate thrombectomy is the best option. Currently, we have more and more imaging tools that yield data in favor of offering endovascular treatment despite a low ASPECTS. The use of collateral status allows us to offer this treatment to patients who until now were discarded, and despite the limitations of the study, they lay the foundations for broader investigations.