A patient in their 40s was transported to the emergency department by ambulance for sudden acute chest pain that had been present for 1 hour. The patient did not have dyspnea or history of cardiac disease. The electrocardiogram (ECG) obtained in the ambulance is shown in the Figure, A. In the ambulance, the patient received nitroglycerin intravenously. On arrival, the patient’s temperature was 36.4 °C, heart rate was 76 beats/min, and blood pressure was 90/56 mm Hg. Jugular distention was visible. No crackles were auscultated in the lungs. The initial serum troponin I and D-dimer levels were 0.03 ng/mL (normal range, ≤0.05 ng/mL; to convert to µg/L, multiply by 1.0) and 0.32 μg/mL (normal range, 0-0.55 μg/mL; to convert to nmol/L, multiply by 5.476), respectively. Peripheral oxygen saturation was 97% on room air. In the emergency department, a right ventricular and posterior wall ECG was obtained (Figure, B). Transthoracic echocardiography revealed severe global systolic dysfunction of the right ventricle (RV) with akinesia of the RV free wall and normal left ventricular systolic function.