A 68-year-old man is evaluated at a follow-up appointment. He has a 7-year history of heart failure secondary to ischemic cardiomyopathy. Over the past 6 months, he has had three hospitalizations for exacerbations of his heart failure. He currently has exertional dyspnea while getting dressed, and his maximal activity level is limited to riding to the store with his wife but staying in the car. Medical history is significant for disseminated prostate cancer treated with androgen deprivation therapy. Medications are aspirin, lisinopril, carvedilol, furosemide, digoxin, spironolactone, rosuvastatin, and leuprolide. He is stable on his current medications.

On physical examination, blood pressure is 92/60 mm Hg and pulse rate is 80/min. There is no jugular venous distention. An S3 is heard on cardiac examination. The legs are cool to the touch; there is no edema.

Laboratory studies are significant for a serum sodium level of 132 mEq/L (132 mmol/L) and serum creatinine level of 1.8 mg/dL (159 µmol/L).

Which of the following is the most appropriate management?