A 71-year-old woman named B.D. presented to the emergency department with a two-week history of fatigue, cough, and dyspnea. She complained that morning of a sudden worsening of respiratory symptoms, and a chest x-ray demonstrated an enlarged cardiac silhouette and left pleural effusion. Routine laboratory tests showed anemia, elevated liver enzymes, and renal insufficiency. A computed tomography (CT) scan of the thorax was ordered, revealing lung and liver lesions with a pericardial effusion. A follow-up 2D echocardiogram showed a pericardial effusion with evidence of cardiac tamponade. B.D. deteriorated rapidly in the emergency department. She had a decreased level of consciousness and was hypotensive with distended neck veins and muffled heart sounds. An electrocardiogram showed a rapid atrial fibrillation with electrical alternans. A echo-guided pericardiocentesis was performed at bedside. B.D. suffered cardiac arrest during the procedure but was successfully resuscitated. Two liters of fluid were drained from the pericardial sac. A surgical referral was requested for a pericardial window and an oncology referral was made because this was B.D.'s de novo presentation of metastatic disease.