Cardiopulmonary arrest research and guidelines have generally focused on the treatment and management of ventricular fibrillation and pulseless ventricular fibrillation (electrical shockable rhythms). Less investigation has been done on the subpopulation of cardiopulmonary arrest victims that present with non-shockable rhythms. In a new paper, Goto, Maeda, and Goto present evidence that early use of epinephrine for treatment is associated with better survival with functional outcome. While there is a lack of evidence to support epinephrine for management of cardiopulmonary arrest presenting with initial shockable rhythms (presumed primary cardiac origin), there is now evidence that epinephrine may potentially benefit those presenting with non-shockable cardiopulmonary arrest (presumed heterogeneous origins). Further research on non-shockable rhythm cardiopulmonary arrest is needed to understand the subpopulation and develop better treatment guidelines.