A 60-year-old man comes t...

A 60-year-old man comes to the physician because of progressive fatigue and shortness of breath for 2 months. The dyspnea occurs on moderate exertion and during the night; he sometimes wakes up coughing and “gasping for air.” He has also had several episodes of heart pounding. Two weeks ago, he had a runny nose and a productive cough. He has type 2 diabetes mellitus and peripheral arterial disease. He has never smoked. He drinks one to two beers occasionally. He has a history of intravenous illicit drugs use but has not used in over 25 years. Current medications include aspirin, atorvastatin, and metformin. Vital signs are within normal limits. Examination shows bilateral basilar rales. Cardiac auscultation is shown (in the video above).