A 68-year-old man presents to your clinic for a scheduled appointment. He says that he called the clinic about three weeks ago with “the flu” but could not get an appointment until today. He reports that he was feeling “really bad” back then but could not be more specific. With coaxing, you discover that he was significantly short of breath for four or five days and that his legs were swollen. He tried to work but could not function.

The patient reports that, although his symptoms have improved during the past week, he still does not “feel right.” His history is remarkable for gastroesophageal reflux disease, hypertension, and hypercholesterolemia. He has not been compliant with his hydralazine or simvastatin regimen.

Physical examination reveals a blood pressure reading of 168/98 mm Hg; pulse, 50 beats/min; respirations, 18 breaths/min. His weight is up 5 lb from his last visit a year ago. You notice a new early systolic murmur, and there is an S3 gallop. The lower extremities are remarkable for 2+ pitting edema to the midcalf.

A chest x-ray shows a small left pleural effusion. The electrocardiogram (ECG) shows sinus bradycardia with a ventricular rate of 48 beats/min; PR interval, 179 ms; QRS duration, 92 ms; QT/QTc intervals, 471/421 ms; P axis, -15º; R axis, -5º; and T axis, -17º. There are Q waves in leads III and aVF.

Considering the patient’s clinical history, the physical examination findings, and your interpretation of the ECG, what is your diagnosis?