A 63-year-old man with ischaemic cardiomyopathy (LVEF 28%) is reviewed in a heart failure clinic. He is in sinus rhythm with a resting heart rate of 76 beats/min and BP 118/70 mm Hg. Current medications include sacubitril-valsartan at target dose, bisoprolol at target dose, spironolactone 25 mg daily, and furosemide 40 mg daily. He has New York Heart Association (NYHA) class II-III symptoms and has had one heart failure hospitalisation in the past year. Which additional therapy has the best evidence to further reduce cardiovascular death and heart failure hospitalisation?