New grading system for angiographic evaluation of arterial occlusions and recanalization response to intra-arterial thrombolysis in acute ischemic stroke

Abstract

Objective: The Thrombolysis in Myocardial Infarction (TIMI) grading scheme and other classification systems are limited because they do not account for occlusion location or collateral circulation. A new scheme for angiographic classification of arterial occlusion and recanalization response to intra-arterial thrombolysis in acute ischemic stroke was designed because of limitations in existing grading systems.

Methods: The proposed scheme assigns a score from 0 to 5 on the basis of occlusion site and collateral supply. The pre- and post-thrombolysis angiograms of 15 patients with acute ischemic stroke were independently graded by three neurointerventionists according to TIMI perfusion grade (0-3), a grading scheme developed by Mori et al. (Mori E, Tabuchi M, Yoshida T, Yamadori A: Intracarotid urokinase with thromboembolic occlusion of the middle cerebral artery. Stroke 19:802-812, 1988) (0-4), and the proposed scheme (0-5); and interobserver agreement was assessed. The effect of severity of initial arterial occlusion on outcomes of good recovery (National Institutes of Health Stroke Scale score of < or =4) or death at 7 days after thrombolysis according to the proposed and TIMI grading schemes was also assessed in 60 patients with acute ischemic stroke. Multivariate analyses were performed to assess these relationships after adjusting for patient age, sex, time interval between symptom onset and treatment, and thrombolytic agent used.

Results: Interobserver agreement was higher for pre- and posttreatment grading of angiographic images using the new classification scheme (kappa = 0.73) than with either TIMI perfusion grade (kappa = 0.68) or Mori et al. grade (kappa = 0.68). The proposed grading scheme was inversely associated with good recovery at 7 days (odds ratio, 0.4; 95% confidence interval, 0.2-0.9) and directly associated with 7-day mortality (odds ratio, 2.0; 95% confidence interval, 1.1-3.6) after treatment. Initial TIMI grade did not correlate with either good recovery or death at 7 days. An inverse trend was observed between initial severity of angiographic occlusion as determined by the proposed scheme and complete recanalization after treatment (odds ratio, 0.6; 95% confidence interval, 0.4-1.02).

Conclusion: Application of the new classification scheme for assessing pretreatment occlusion and response to intra-arterial thrombolysis resulted in high interobserver agreement and correlated with 7-day outcomes. The six grades used in this scheme allowed precise angiographic evaluation of perfusion changes.