A patient in their 20s without a noteworthy medical history presented to the emergency department with chest pain and dyspnea. The patient began experiencing palpitations and symptoms of upper respiratory tract infection 3 days prior. Vital signs revealed a temperature of 36.5 °C, heart rate of 88 beats per minute, respiratory rate of 22 breaths per minute, blood pressure of 105/70 mm Hg, and oxygen saturation of 89% on room air. The initial electrocardiogram (ECG) is shown in Figure, A. The patient lost consciousness 20 minutes after arriving to the emergency department, and blood pressure decreased to 67/43 mm Hg. The ECG obtained after cardiopulmonary resuscitation and defibrillation is shown in Figure, B. Testing results revealed elevated levels of troponin T (4.74 μg/L; normal range, 0-0.03 μg/L) and pro–brain natriuretic peptide (4850 pg/mL; normal range, <300 pg/mL; to convert to ng/L, multiple by 1.0). C-reactive protein was elevated to 18.50 mg/L (normal range, 0-6 mg/dL; to convert to mg/L, multiply by 10), and procalcitonin was elevated to 39.68 ng/mL (normal range, 0-0.05 ng/mL). Findings from transthoracic echocardiography revealed severe left ventricular dysfunction (ejection fraction, 38%) and wall motion abnormalities in multiple vascular territories.