Abstract WMP5: CT Perfusion Profiles of Infarct Growth in Large Vessel Occlusion Acute Stroke Patients Sensitive to Decreases in Blood Pressure

Abstract

The growth of a final infarct volume largely depends on cerebral perfusion after a large vessel occlusion (LVO) stroke. Decreases of blood pressure (BP) before recanalization are associated with larger infarct and worse functional outcome. It is uncertain whether an intervention to elevate BP improves outcome, particularly if susceptibility to the BP beneficial effect varies by individual factors such as the collateral vessel status. We aim to define the association of BP, infarct growth and perfusion patterns of potential vulnerable patients. We retrospectively studied patients with anterior LVOs who underwent mechanical thrombectomy (MT) at two comprehensive stroke centers. Only patients with TICI score ≥2b and admission CTP and 24 hours MRI were included. Infarct growth was calculated as 620 ADC volume subtracted from CBF <30% in the ischemic hemisphere using the Automatic Rapid Software. Hypoperfusion intensity ratio (HIR) was calculated as the ratio of the Tmax >10s volume to the Tmax >6s volume with a lower value indicating a more favorable ratio. Intra-procedural BP was continuously monitored using a non-invasive cuff or intraarterial catheter. Systolic BP (SBP) and mean arterial pressure (MAP) were averaged at various time points throughout MT. We analyzed 199 patients from 317 MT. A quantile regression with quantile τ = 0.25, 0.5 and 0.75 was fitted to study how Infarct Growth Rate (IGR) is affected by BP change. At 0.25 and 0.5 quantiles, one unit change in MAP did not lead to a significant change for IGR. At the 0.75 quantile (quartile 3), one unit change in MAP resulted in 0.79 unit change in IGR (95% CI: -0.11, 1.69; p= 0.09). Hence, we identified patients whose IGR is above the 0.75 quantile as the vulnerable subgroup. The vulnerable subgroup had significant larger median volumes of Tmax in all sequences when compared to the non-vulnerable subgroup: Tmax10 (67.8cc vs 40.0cc, p= 0.004), Tmax8 (92.9cc vs 62.0cc, p= 0.003), Tmax6 (134cc vs 98.7cc, p =0.003), Tmax4 (228.6cc vs 184.3cc, p= 0.016). The median HIR was also significantly higher (0.4 vs 0.3, p= 0.026) in the BP vulnerable population. Admission perfusion patterns of collaterals evaluated may help to identify the most vulnerable population to increase their infarct growth when facing decrease in BP.