mTICI 1 vs. mTICI 0 before endovascular stroke treatment in middle cerebral artery M1-occlusion - predictor for revascularization success and outcome?

Background - Endovascular stroke treatment (EST) has become the treatment of choice for middle cerebral artery (MCA) M1-segment occlusions. Little is known about the implications for revascularization success of an M1-occlusion with persisting antegrade perfusion before initiation of treatment (modified Treatment In Cerebral Ischemica (mTICI 1)) compared to a complete occlusion (mTICI 0). Here, we compared the impact of these two states of target vessel occlusion on recanalization success and clinical outcome. Methods - Retrospective, single-center analysis of patients treated for M1-segment MCA occlusion with EST from 01/2015 until 05/2020 in a tertiary stroke center. Primary study endpoint was successful recanalization (mTICI 2c-3) after one thrombectomy attempt (first pass effect). Secondary endpoints were the clinical outcome (as modified Rankin Scale 90 days after stroke onset) and the complication rate. The two study groups were compared in univariate analysis including patient characteristics and procedural details. Results - In this study, 422/581 patients (72.6%) presented with complete M1-occlusion compared to 159/581 (27.4%) with incomplete M1-occlusion. Neither did the rate of FPE differ between the study groups nor the rate of procedural complications (mTICI=: 10 (2.4%), mTICI 1: 1 (0.6%), p = 0.304). Patients with incomplete initial occlusion showed a lower mRS at discharge (median (IQR) mTICI0: 4 (3-5) vs. mTICI 1: 3 (2-6), p = 0.014), but a comparable mRS 90 days after stroke onset (mTICI0: 3 (2-6) vs. mTICI1: 4 (2-6), p =0.479). Conclusion - Complete M1-occlusions (mTICI 0) and incomplete occlusions (mTICI 1) show the same recanalization success and complication rate. The study groups showed a comparable clinical outcome 90 days after stroke onset. Thus, incomplete M1-occlusions should be treated with the same urgency as initial complete occlusions.