A 58-year-old man from Delhi presents to the emergency department with acute onset left-sided weakness and facial droop. CT head (non-contrast) is normal. MRI brain shows acute infarction in the right middle cerebral artery (MCA) territory. Carotid duplex shows 85% stenosis of the right internal carotid artery (ICA). The patient is within the thrombolytic window. What is the most appropriate next step in management?