Abstract
Background and purpose: To elucidate whether the effects of alteplase differ with occlusion site of the middle cerebral artery (MCA).
Methods: An exploratory analysis was made of 57 patients enrolled on the Japan Alteplase Clinical Trial II (J-ACT II). The residual vessel length (mm), determined on pretreatment MRA, was used to reflect the occluded site. The proportions of patients with valid recanalization (modified Mori grade 2–3) at 6 and 24 hours, and a favorable outcome (modified Rankin scale 0–1 at 3 months) were compared between the groups dichotomized according to their lengths of residual vessel. Multiple logistic regression models were generated to elucidate the predictors of valid recanalization and a favorable outcome.
Results: ROC analysis revealed that 5 mm was the practical cutoff length for the dichotomization. In patients with M1 length <5 mm (n=12), the frequencies of valid recanalization at 6/24 hours (16.6%/25.0%) were significantly low compared with those (62.2%/82.2%) of 45 patients with a residual M1 length of ≥5 mm and M2 occlusions (p=0.008 for 6 hours, p<0.001 for 24 hours). The proportion of a favorable outcome was also small in patients with M1 length <5 mm (8.3%), as compared to the others (57.8%, p=0.004). In logistic regression models, the site of MCA occlusion (<5 mm) was the significant predictor of valid recanalization at 6/24 hours and of a favorable outcome.
Conclusions: In patients with acute MCA occlusion, residual vessel length <5 mm on MRA can identify poor responders.
