Question

A 63-year-old woman is brought to the emergency department from an inpatient rehabilitation facility due to sudden-onset severe shortness of breath and lightheadedness. Two weeks ago, she underwent an uncomplicated right total hip arthroplasty. Her medical history includes chronic obstructive pulmonary disease, essential hypertension, and hypothyroidism. Upon arrival, her blood pressure is 76/45 mmHg, heart rate is 126/min, respiratory rate is 28/min, and oxygen saturation is 84% on room air. She appears diaphoretic, agitated, and is using accessory muscles of respiration. Physical examination reveals jugular venous distention up to the angle of the mandible while seated upright. Auscultation of the lungs demonstrates scattered expiratory wheezes. Cardiac examination shows a prominent right ventricular heave, a loud P2, and a grade 2/6 holosystolic murmur at the left lower sternal border. The right thigh and calf are moderately swollen and tender. An electrocardiogram shows sinus tachycardia, new-onset complete right bundle branch block, and T-wave inversions in leads V1 through V4. Laboratory studies show a serum troponin I of $0.8$ ng/mL (normal $<0.04$), thyroid-stimulating hormone of $1.2$ $\mu U/mL$ (normal $0.4-4.0$), and free T4 of $0.6$ ng/dL (normal $0.9-1.7$). Which of the following is the most appropriate next step in the management of this patient?