Electrical alternans is defined as alternating QRS amplitude that is seen in any or all leads on an electrocardiogram (ECG) with no additional changes to the conduction pathways of the heart. This rhythm is typically associated with pericardial effusion via the “swinging heart” from the fluid surrounding the heart. However, electrical alternans is also associated with other pathologies including but not limited to ventricular tachycardia, Wolff-Parkinson-White (WPW), accelerated idioventricular rhythm, and supraventricular tachycardia. Understanding the varied pathologies causing this ECG finding is key to evaluation and if necessary, treatment success.