Refining angiographic biomarkers of revascularization: improving outcome prediction after intra-arterial therapy

Abstract

Background and purpose: Angiographic revascularization grading after intra-arterial stroke therapy is limited by poor standardization, making it unclear which scale is optimal for predicting outcome. Using recently standardized criteria, we sought to compare the prognostic performance of 2 commonly used reperfusion scales.

Methods: Inclusion criteria for this multicenter retrospective study were acute ischemic stroke attributable to middle cerebral artery M1 occlusion, intra-arterial therapy, and 90-day modified Rankin scale score. Post-intra-arterial therapy reperfusion was graded using the Thrombolysis in Myocardial Infarction (TIMI) and Modified Thrombolysis in Cerebral Infarction (mTICI) scales. The scales were compared for prediction of clinical outcome using receiver-operating characteristic analysis.

Results: Of 308 patients, mean age was 65 years, and median National Institutes of Health Stroke Scale score was 17. The mean time from stroke onset to groin puncture was 305 minutes. There was no difference in the time to treatment between patients grouped by final TIMI (ie, 0 versus 1 versus 2 versus 3) or mTICI grades (ie, 0 versus 1 versus 2a versus 2b versus 3). Good outcome (modified Rankin scale, 0-2) was achieved in 32.5% of patients, and mortality rate was 25.3% at 90 days. There was a 6.3% rate of parenchymal hematoma type 2. In receiver-operating characteristic analysis, mTICI was superior to TIMI for predicting 90-day modified Rankin scale 0 to 2 (c-statistic: 0.74 versus 0.68; P<0.0001). The optimal threshold for identifying a good outcome was mTICI 2b to 3 (sensitivity 78.0%; specificity 66.1%).

Conclusions: mTICI is superior to TIMI for predicting clinical outcome after intra-arterial therapy. mTICI 2b to 3 is the optimal biomarker for procedural success.

Keywords: TIMI; acute ischemic stroke; endovascular; intra-arterial therapy; modified TICI; revascularization.

Figure 1

Example of Modified Thrombolysis in Cerebral Infarction 2a (mTICI 2a). Lateral projection images of M1 occlusion at baseline (A), post-treatment early arterial (B), and late parenchymal-venous (C) phases demonstrate restoration of antegrade flow into the inferior division branches, which produces a capillary blush in <50% of the middle cerebral artery territory (dotted ovals).

Figure 2

Example of Modified Thrombolysis in Cerebral Infarction 2b (mTICI 2b). Lateral projection images of M1 occlusion at baseline (A), post-treatment early arterial (B), and late parenchymal (C) phases demonstrate restoration of antegrade flow into the dominant superior division branches, which produces a capillary blush in >50% of the middle cerebral artery territory (dotted ovals).

Figure 3

Proportion of good outcomes by mTICI grade (P<0.0001 for overall comparison). In successive stepwise comparison, the only significant difference was between mTICI 2a and 2b (P<0.0001); there was a trend for the difference between mTICI 2b and 3 (P=0.09). mRS indicates modified Rankin scale; and mTICI, modified thrombolysis in cerebral infarction.