Arterial occlusion sites on magnetic resonance angiography influence the efficacy of intravenous low-dose (0.6 mg/kg) alteplase therapy for ischaemic stroke

Abstract

Aims: To determine the predictors of efficacy, including magnetic resonance imaging information, for low-dose intravenous alteplase therapy for stroke patients.

Methods: Seventy-eight patients were prospectively enrolled in a single Stroke Unit (SU) receiving alteplase at a dose of 0.6 mg/kg during the initial 27 months after its approval in Japan. Ischaemic changes and vascular lesions were identified using computed tomography, diffusion-weighted magnetic resonance imaging, and magnetic resonance angiography. Early ischaemic signs were assessed using the Alberta Stroke Program Early CT Score.

Results: The median baseline National Institutes of Health Stroke Scale score of 78 patients was 12. In 19 patients (24%), the National Institutes of Health Stroke Scale score improved by >or=8 points at 24 h. After multivariate adjustment, occlusion at the internal carotid artery (odds ratio 11.82, 95% confidence interval 1.73-142.74), Alberta Stroke Program Early CT Score on diffusion-weighted imaging <or=6 (15.23, 1.88-351.50), and a lower National Institutes of Health Stroke Scale score (1.24, 1.08-1.47, per 1-point decrease) were inversely correlated with early improvement. Four patients (5%) had symptomatic intracranial haemorrhage. At 3 months, 76 patients (98%) survived, and 36 of 78 patients (46%) overall, but only two of 19 patients (11%) with internal carotid artery occlusion, had a favourable functional outcome, corresponding to a modified Rankin scale score <or=1. After multivariate adjustment, internal carotid artery occlusion (odds ratio 15.84, 95% confidence interval 3.12-128.69) and Alberta Stroke Program Early CT Score on diffusion-weighted imaging <or=6 (15.62, 1.78-410.12) were independent predictors of poor outcome.

Conclusions: Intravenous alteplase therapy at a dose of 0.6 mg/kg resulted in a relatively good overall outcome when compared with outcomes reported by western studies using an alteplase dose of 0.9 mg/kg. However, patients with occlusion at the internal carotid artery did not respond to this low-dose alteplase therapy.