Review Question - QID 210421

A 61-year-old man is brought to the emergency room with chest pain. He developed severe, crushing, substernal chest pain 10 hours ago while he was hiking in the Adirondack mountains. He was with 2 friends at the time who gave him aspirin before carrying him 5 miles to a town to get phone service, where they then called emergency medical services. His past medical history is notable for hypertension, diabetes mellitus, and hyperlipidemia. He takes enalapril, metformin, and atorvastatin. He has a 20-pack-year smoking history and is an avid hiker. His temperature is 100°F (37.8°C), blood pressure is 102/60 mmHg, pulse is 130/min, and respirations are 28/min. He is diaphoretic and intermittently conscious. Bilateral rales are heard on pulmonary auscultation. An electrocardiogram demonstrates ST elevations in leads I and aVL. Despite appropriate management, the patient expires. An autopsy is performed demonstrating ischemia in the left atrium and posterior left ventricle. Which of the following vessels was most likely affected in this patient?