A 68-year-old man with a previous anterior myocardial infarction and reduced left ventricular ejection fraction (30%) remains symptomatic NYHA class II on optimal doses of an ACE inhibitor, evidence-based beta-blocker and mineralocorticoid receptor antagonist. Blood pressure is 110/70 mm Hg and eGFR is 70 mL/min/1.73 m². According to CCS heart failure guidance, which additional therapy should be prioritised to reduce mortality and hospitalisation?