A 55-year-old man with stable angina experiences chest pain 2-3 times per week on moderate exertion, relieved by GTN spray. He is already on aspirin 75mg OD and atorvastatin 80mg OD. His blood pressure is 130/80 mmHg and heart rate is 70 bpm. According to NICE guidelines, what is the most appropriate next step in his pharmacological management?