A 74-year-old man with long-standing hypertension and diabetes presents with bilateral leg swelling and fatigue. Laboratory tests: eGFR 25 mL/min/1.73 m², creatinine 210 µmol/L, urea 15 mmol/L, potassium 5.2 mmol/L, Hb 105 g/L. Urine ACR 80 mg/mmol. Blood pressure is 132/78 mmHg on ramipril and amlodipine. According to CKD guidelines, which additional therapy is most appropriate to reduce cardiovascular risk?