A 55-year-old man with a history of hypertension and hyperlipidemia presents to the ED with sudden-onset pleuritic chest pain and dyspnea. He recently completed a transatlantic flight. His vital signs show HR 110/min, BP 130/80 mmHg, RR 28/min, SpO2 90% on room air. ECG shows sinus tachycardia. What is the most appropriate initial diagnostic test?

The correct answer to the question "A 55-year-old man with a history of hypertension and hyperlipidemia presents to the ED with sudden-onset pleuritic chest pain and dyspnea. He recently completed a transatlantic flight. His vital signs show HR 110/min, BP 130/80 mmHg, RR 28/min, SpO2 90% on room air. ECG shows sinus tachycardia. What is the most appropriate initial diagnostic test?" is Option C: CT pulmonary angiography.

The other options — A) Chest X-ray, B) D-dimer assay, D) Ventilation-perfusion scan — are incorrect for this USMLE Exam Prep question. As explained above: Given the high suspicion for pulmonary embolism (sudden pleuritic chest pain, dyspnea, risk factors like recent long flight, and hypoxemia), CT pulmonary angiography is the gold standard for diagnosi…