A woman in her early 40s, gravida 3, para 3, with a history of migraines and recurrent preeclampsia and who was 11 weeks post partum presented with acute pleuritic chest pain, shortness of breath, and nausea that started several hours after a flight from Florida to New York City. She was noted to have tachycardia (110 beats/min) and hypoxemia (90% receiving room air) with a blood pressure of 106/81 mm Hg. Cardiac, respiratory, and pulse examination results were unremarkable. She denied any clear physical or emotional triggers preceding presentation. Before presentation, the patient reported good health with satisfactory employment-mandated routine physical examinations. She denied a history of smoking, alcohol, or illicit drug use. She was not taking hormonal birth control or hormone therapy. Laboratory values demonstrated a normal complete blood cell count and metabolic panel. Chest radiograph results were unremarkable. A computed tomographic chest scan excluded pulmonary embolism but suggested pulmonary and interstitial edema. Results of an electrocardiogram revealed sinus tachycardia with premature ventricular contractions, subcentimeter ST-segment elevation in leads I and aVL and 1-mm ST-segment depression in leads II, III, aVF, and V5 through V6. Initial high-sensitivity troponin was 110 000 ng/mL (to convert to micrograms per liter, multiply by 1). Results of cardiac point-of-care ultrasonography demonstrated a severely reduced left ventricular ejection fraction of 40%, with hypokinesis of the anterolateral and posterior walls. Emergent cardiac catheterization revealed spontaneous coronary artery dissection (SCAD) of the left main coronary artery (Figure 1 and Video).