THrombolysis for Acute Wake-up and unclear-onset Strokes with alteplase at 0·6 mg/kg (THAWS) Trial

Rationale: Because of lack of information regarding timing of stroke, patients who suffer stroke during sleep are generally ineligible for intravenous thrombolysis, although many of these patients could potentially recover with this treatment. Magnetic resonance image findings with positive diffusion-weighted imaging and no marked parenchymal hyperintensity on fluid-attenuated inversion recovery (negative pattern) can identify acute ischemic stroke patients within 4·5 h from symptom onset.

Aims: The THrombolysis for Acute Wake-up and unclear-onset Strokes with alteplase at 0·6 mg/kg trial aims to determine the efficacy and safety of intravenous thrombolysis with alteplase at 0·6 mg/kg body weight, the approved dose for Japanese stroke patients, using magnetic resonance image-based selection in ischemic stroke patients with unclear time of symptom onset, and compare findings with standard treatment.

Design: This is an investigator-initiated, multicenter, prospective, randomized, open-treatment, blinded-end-point clinical trial. The design is similar to the Efficacy and Safety of MRI-based Thrombolysis in Wake-up Stroke trial. Patients with unclear-onset time of stroke symptoms beyond 4·5 h and within 12 h after the time of the last-known-well period and within 4·5 h after symptom recognition, who showed a negative fluid-attenuated inversion recovery pattern, are randomized to either intravenous thrombolysis or standard treatment.

Study outcomes: The primary efficacy end-point is modified Rankin Scale 0-1 at 90 days. The safety outcome measures are symptomatic intracranial hemorrhage at 22-36 h, and major bleeding and mortality at 90 days.

Discussion: This trial may help determine if low-dose alteplase at 0·6 mg/kg should be recommended as a routine clinical strategy for ischemic stroke patients with unclear-onset time.