A 58-year-old woman with a history of transient ischaemic attack (TIA) 2 months ago is reviewed in clinic. Carotid Doppler showed 40% stenosis bilaterally. She is on aspirin 100 mg daily and atorvastatin 40 mg nocte. BP averages 136/82 mmHg, HbA1c 5.8%. What is the most appropriate additional therapy to reduce her stroke risk?