We make no recommendation about the routine prophylactic use of antiarrhythmic drugs post after ROSC (GRADE used for evidence evaluation and synthesis only, very low confidence in effect estimate). Values, Preferences, and Task Force Insights The available data were too limited to have any confidence in any effect, and, therefore, no recommendation is made. We also place value on avoiding known side effects of medications when the treatment effect was unproven or unknown. The studies evaluated were all observational, and no causal relation could be determined. Moreover, they were performed before changes in current practice (ie, currently amiodarone is used during cardiac arrest more than lidocaine).