Soru

A 54-year-old woman presents to the outpatient clinic reporting a three-week history of progressively worsening exertional dyspnea, fatigue, and bilateral lower extremity swelling. She states that she now requires three pillows to sleep comfortably at night without waking up short of breath. Her medical history is significant for estrogen-receptor-negative, HER2-positive breast cancer, for which she underwent surgical resection and completed a chemotherapy regimen containing doxorubicin and cyclophosphamide six months ago. She is currently receiving maintenance therapy with trastuzumab. Vital signs show a temperature of $37.1^\circ C$ ($98.8^\circ F$), heart rate of $105\text{ /min}$, respiratory rate of $22\text{ /min}$, and blood pressure of $114/74\text{ mmHg}$. Pulse oximetry is $94\%$ on room air. Physical examination reveals an elevated jugular venous pressure of $9\text{ cm H}_2\text{O}$, fine bibasilar crackles, and a distinct third heart sound ($S_3$). Pitting edema is present to the mid-calves bilaterally.

Recent laboratory studies are as follows:

Which of the following is the most appropriate next step in management?