A 53-year-old male with several cardiac risk factors presented to the emergency department with backpain and an electrocardiogram concerning for an anterior ST-elevation myocardial infarction. The patientdecompensated hemodynamically and a point-of-care ultrasound revealed a small pericardial effusion.An aortic dissection was ruled out by computed tomography angiography and coronary catheterization didnot reveal a culprit lesion. The diagnosis of tamponade was made in the catheterization laboratory aftermeasurement of intra-cardiac diastolic pressures and the patient’s symptoms resolved after drainage of 100mL of pericardial fluid.