A 58-year-old man from Delhi presents to the emergency department with acute onset left-sided weakness and slurred speech of 2 hours duration. Blood pressure is 165/95 mmHg, heart rate 88/min regular. Non-contrast CT head shows no hyperdensity. MRI brain performed 3 hours after symptom onset reveals restricted diffusion in the right middle cerebral artery territory on DWI sequences with corresponding low signal on ADC maps. What is the most appropriate next step in management?