Background and purpose: The Thrombolysis in Cerebral Infarction (TICI) 2b classification is defined as “near complete” recanalization for acute ischemic stroke. While this category has historically combined with TICI 3 (“complete reperfusion”) as “successful recanalization”, recent studies have suggested that TICI 3 and a proposed intermediate TICI 2c (“near complete reperfusion except for slow flow or distal emboli”) should be distinguished from TICI 2b due to differences in outcomes. In this study, we examined if early neurologic improvement differed significantly between patients with TICI 2b, TICI 2c, and TICI 3 recanalization for emergent large vessel occlusions treated with mechanical thrombectomy (MT).
Methods: Retrospective analysis was performed using data from 133 consecutive patients with middle cerebral artery or internal carotid artery occlusions treated with MT from January 2015 to June 2016. Patient angiograms were graded independently and blinded to clinical data by two experienced readers based on original TICI (oTICI), modified TICI (mTICI), and modified TICI with TICI 2c (mTICI 2c) grading scales. Early neurologic improvement was assessed using change in NIHSS by discharge. General linear modeling was used to evaluate difference in NIHSS delta scores between TICI scales with SAS/PROC GLIMMIX. Multiple comparisons were evaluated using Tukey corrections with significance established at the .05 level.
Results: Without the TICI 2c category, there was not a significant difference in change in NIHSS observed between TICI 3 and TICI 2b for both the oTICI (delta 1.4, p=0.355) and mTICI scales (delta 2.1, p=0.190). However, when an additional category (TICI 2c) was added, there was a significant difference in change in NIHSS observed between TICI 3 and TICI 2b (delta 3.8, p= 0.026) as well as between TICI 2c and TICI 2b (delta 3.7, p=0.019).
Conclusion: Utilizing a TICI recanalization grading system that adds an additional category beyond TICI 2b allows for improved prediction of neurological improvement in patients treated with MT. Higher levels of recanalization are associated with greater neurologic improvement.