Abstract A036: Increased Focal Microvascular Resistance rather than Hyperemia Predicts Decreased Response to Successful Endovascular Reperfusion in Large Vessel Occlusion Stroke

Background: Excessive hyperemia and failed microvascular reperfusion have been linked to poor outcomes after successful endovascular therapy (EVT) for large-vessel occlusion stroke. We tested whether post-EVT transcranial doppler (TCD) indices of focal hyperemia or increased microvascular resistance in the reperfused MCA territory were associated with outcomes. Methods: This was a single-center retrospective study of adults with MCA or intracranial ICA occlusion who underwent adequate TCD 24–72 h after successful EVT (eTICI ≥2b50) from 8/2023 to 3/2025. Bilateral MCA mean flow velocity (MFV), peak systolic velocity (PSV), end-diastolic velocity (EDV), and pulsatility index (PI) were measured; stroke ipsilateral/contralateral ratios (MFV-R, PSV-R, EDV-R, PI-R) were computed. Focal hyperemia (MFV-R or PSV-R >1) and increased microvascular resistance (EDV-R<1 or PI-R>1) were tested for association with: early neurological improvement (ENI; DNIHSS≥4), early neurological deterioration (END; DNIHSS ≥4), hemorrhagic transformation (HT), and poor 90-day outcome (mRS 5–6). Multivariable logistic regression adjusted for age, sex, time from stroke onset to arrival, NIHSS, ASPECTS, IV thrombolysis, and eTICI. Results: A total of 165 patients were included (median age 73; 50% women; median NIHSS 17; 83% MCA occlusion; 23% IVT; 61% eTICI 2c–3). On unadjusted comparisons, ENI patients (n= 127, 77%) had higher MFV-R (p=0.04) and EDV-R (p=0.02), and lower PI-R (p=0.02); mRS 5–6 patients (n=39, 24%) had lower EDV-R (p=0.02) and a trend toward higher PI-R (p=0.05). In adjusted models, higher PI-R predicted lower odds of ENI (OR 0.08; 95% CI 0.01–0.82; p=0.03), higher odds of END (OR 27.3; 1.3–567.3; p=0.03), and higher odds of mRS 5-6 (OR 11.9; 1.4–98.3; p=0.02). Higher EDV-R associated with lower mRS 5-6 (OR 0.3; 0.1–0.9; p=0.03) and trended toward ENI (OR 2.8; 0.9–8.2; p=0.07). Higher PSV-R was associated with END (OR 7.3; 1.1–50.2; p=0.04). MFV-R trended toward lower odds of mRS 5-6 (OR 0.3; 0.09–1.1; p=0.07). No indices were associated with HT. Conclusions: Early TCD evidence of increased focal microvascular resistance after successful EVT independently correlated with worse early and 90-day outcomes, while relative hyperemia did not predict harm and may favor early improvement. These findings support the pragmatic use of TCD to monitor incomplete microvascular reperfusion, and its applications toward individualized blood pressure management post-EVT in future prospective studies.