A 48-year-old man presents to the emergency department with shortness of breath. He reports that 6 months ago he was able to walk several miles without stopping. Yesterday, he became short of breath walking from his bed to the bathroom. He also endorses worsening abdominal distension and leg swelling, which he reports is new from several months ago. The patient has a past medical history of hypertension and hyperlipidemia. On physical exam, the patient has moderate abdominal distension and pitting edema to the knee. Crackles are present at the bilateral bases. Laboratory testing reveals the following:
Hemoglobin: 13.4 g/dL
Mean corpuscular volume (MCV): 102 um^3
Leukocyte count: 11,200 /mm^3 with normal differential
Platelet count: 256,000/mm^3
Serum:
Na+: 137 mEq/L
Cl-: 100 mEq/L
K+: 4.2 mEq/L
HCO3-: 25 mEq/L
BUN: 18 mg/dL
Glucose: 126 mg/dL
Creatinine: 0.9 mg/dL
Alkaline phosphatase: 88 U/L
Aspartate aminotransferase (AST): 212 U/L
Alanine aminotransferase (ALT): 104 U/L
Which of the following is the best next step in management?