Prabhakaran, Shyam

Background: Tissue reperfusion is a critical determinant of outcomes after intra-arterial therapy (IAT). However, there is no standardized method for grading angiographic reperfusion. We sought to compare the two most commonly used reperfusion scales, TIMI and modified TICI (m-TICI), for predicting good long-term outcome following IAT. Methods: From a multicenter database, we evaluated acute stroke patients presenting with middle cerebral artery (MCA) M1 occlusions who underwent IAT. Clinical and angiographic data were collected. Reperfusion for each case was graded using the TIMI and m-TICI scales. The primary distinction between these scales is that partial reperfusion (TIMI 2) is sub-divided into minor (m-TICI 2A: <50%) and major (m-TICI 2B: 50-99%) grades in the m-TICI system. The performance of these scales for predicting a good 90-day outcome (mRS 0-2) was evaluated using the c-statistic. Results: There were 313 acute stroke patients with MCA M1 segment occlusions who underwent IAT at 6 academic centers; 171 (54.6%) were female. Mean age was 65.3±16.5 years. There were 157 (50.2%) right-sided strokes. Median baseline NIHSS score was 17 (IQR 15-20). Good outcome at 90 days was achieved in 32.5%. For predicting good outcome, the c-statistic was significantly higher for m-TICI (0.74 vs. 0.68; p<0.0001). The threshold that maximized predictive accuracy was m-TICI ≥2B (sensitivity 78%, specificity 65%; figure). Conclusions: The modified TICI scale is superior to the TIMI scale for predicting clinical outcome after IAT, and should be the standard tool for grading angiographic reperfusion. An m-TICI score ≥2B (≥50% reperfusion) is the optimal biomarker for successful reperfusion.