Abstract TMP72: Impaired Perfusion Predicts Early Recurrence in Symptomatic Intracranial Atherosclerosis

Abstract

Background: Intracranial Atherosclerosis (ICAS) leads to stroke by perforator disease, artery to artery embolism, and impaired distal flow/perfusion. While medical treatment is likely to stabilize atherosclerotic plaques, it is unlikely to improve distal perfusion in the acute setting. We hypothesize that medically treated patients with symptomatic ICAS with impaired perfusion have a high risk of recurrence. Methods: We included hospitalized patients with acute ischemic stroke due to ICAS involving the intracranial ICA, proximal MCA, intracranial vertebral artery, or basilar artery over a 3 year period. Patients were treated with medical treatment and followed for 30-days post stroke. Patients generally underwent perfusion imaging with MRI. The study outcome is recurrent ischemic stroke. We used univariate and multivariable Cox regression analyses to determine the association between risk factors, treatment strategies, perfusion delay at T max 4 sec and 6 sec thresholds. To account for multiple admissions per patient, we used robust variance estimator clustering on individual patients. Results: Over the study period, we identified 96 hospitalizations for symptomatic ICAD over 3 years. The recurrence risk within 30 days was 17.7% (17/96). In univariate analysis, factors associated with recurrent risk at 30 days were lack of dual antiplatelet therapy (47.1% versus 22.8%, P=0.068), increased Tmax perfusion mismatch volume as 6 sec (10[0-51] versus 0[0-0], P=0.008) and at 4 sec (60[37-170] versus 13.5[0-91], P=0.050). Using Youden’s index, we identified cutoffs of 6.5 ml and 35.5 ml for Tmax 6 sec mismatch and Tmax 4 sec mismatch respectively. In Cox regression analyses, only predictors of recurrence were T max 6 sec perfusion mismatch > 6.5 ml (aHR 6.72 95% CI 2.01-22.45 p=0.002) and T max 4 sec perfusion mismatch > 35.5 ml (aHR 5.78 95% CI 1.53-21.81 p=0.010). Dual antiplatelet therapy was not associated with reduced recurrence risk (p>0.05) in all models. Conclusions: Patient with symptomatic ICAS and impaired distal perfusion are at high risk of early recurrence. Studies testing reperfusion should focus on this subgroup and enroll patients early, when the risk of recurrence in medically treated patients is highest and likely driven by reperfusion.