Review Question - QID 109339

A 51-year-old woman presents to the emergency room complaining of shortness of breath. Her dyspnea began several months ago and has become progressively worse. She denies chest pain, palpitations, or syncope, but she reports fatigue, hot flashes, and painful joints. Her last menstrual period was 7 months ago. Her medical history is significant for sickle cell disease, for which she receives frequent blood transfusions, type 2 diabetes mellitus, hypertension, and osteoarthritis. Her medications include metformin and lisinopril. The patient’s temperature is 98.6°F (37°C), blood pressure is 130/78 mmHg, pulse is 72/min, and respirations are 14/min with an oxygen saturation of 98% O2 on room air. On physical exam, she has skin hyperpigmentation, elevated jugular venous pressure, hepatomegaly, and bilateral 2+ pitting lower extremity edema. Labs are drawn, with results shown below:

Hemoglobin: 15.9 g/dL
Hematocrit: 38%
Reticulocyte count: 3%
Serum ferritin: 215 µ/L
Serum iron: 202 µg/dL
Transferrin saturation: 55%
TIBC: 220 µg/dL

An EKG is obtained, as shown in Figure A. Echocardiography shows symmetrical thickening of the left ventricle and normal left ventricular volume. In addition to diuretics, which of the following is the most appropriate next step in management for this patient’s cardiac findings?