5, A 74-year-old woman presents to clinic for heart failure follow-up. She is classified as NYHA FC II. Her blood pressure is 144/82 mm Hg, and most recent EF is 26% (0.26). Her current medication regimen includes lisinopril 20 mg Qday, carvedilol 25 mg BID, digoxin 0.125 mg Qday, and furosemide 20 mg BID. Which of the following would be the BEST choice to add at this time?