Abstract 57: Main Results of the CTP to Predict Response to Recanalization in Ischemic Stroke Project (CRISP)

Abstract

Background: Recent acute stroke trials showed benefit from intra-arterial thrombectomy (IAT) up to 6 hrs. We aimed to assess CT Perfusion (CTP) for selection of patients for endovascular therapy up to 18 hrs. Hypothesis: CTP target mismatch profile (TMM) identifies patients likely to benefit from IAT. Methods: The CTP to predict Response to recanalization in Ischemic Stroke Project (CRISP) is an NIH funded multicenter cohort study of consecutive acute stroke patients scheduled to undergo IAT within 90 min after a baseline CTP. Volumes for the CTP ischemic core (rCBF<30%) and critically hypoperfused tissue (Tmax>6s) were computed with automated software (RAPID). Target Mismatch (TMM) was defined as a CBF core <70 mL, a Tmax>6s – core difference >15mL, a Tmax>6s : core ratio >1.8, and a Tmax>10s lesion <100 mL. Reperfusion was defined as >50% reduction in Tmax>6s lesion volume between baseline CTP and follow-up MRI (obtained <36 hrs after CTP), or TICI 2b/3 at completion of IAT if follow-up MRI was not performed/technically inadequate. Good functional outcome (GFO) was defined as mRS 0-2 on day 90. Results: Of the 201 patients enrolled, 6 had inadequate baseline CTP (3%), 3 did not undergo angiography, and 2 were lost to follow-up. Therefore, 190 patients were included; mean age 66 yrs, median NIHSS 16, median time from symptom onset to IAT 5.2 hrs (>6 hrs in 40%). Rate of reperfusion was 89% (87% TICI 2b/3) and 55% had GFO. In patients with TMM (n=131), reperfusion was associated with higher odds of GFO (66% vs 29%; OR=4.3; 95% CI 1.4-13). This association remained significant when adjusted for age and NIHSS (OR=8.4; 95% CI 2.5-28). In patients without TMM (n=51), the effect of reperfusion could not be assessed, since almost all patients (95%) reperfused. Independent of reperfusion status, patients with TMM had a higher rate of GFO (61%) than those without TMM (42%, p=0.02). Conclusion: In this multicenter study, a technically adequate baseline CTP was obtained in nearly all patients and almost half underwent IAT beyond 6 hrs. Patients with the TMM profile had a high rate of GFO (61%) and a robust association between reperfusion and good outcome. These results support the feasibility of a randomized trial of IAT in an extended window using the CTP-TMM profile for patient selection.