A 67-year-old woman with long-standing type 2 diabetes, peripheral arterial disease and previous NSTEMI is on maximal-dose ACE inhibitor, beta-blocker, and high-intensity statin. Her HbA1c is 7.4% on metformin 1 g twice daily. eGFR is 55 mL/min/1.73 m². She continues to smoke 5 cigarettes per day. Which additional pharmacologic therapy is most strongly recommended to reduce her cardiovascular risk?