Whether or not a patient is having a STEMI is a critical factor in deciding whether to take a cardiac arrest patient immediately to the cath lab. However, the post-ROSC ECG can often be difficult to interpret due to global myocardial ischemia. We discuss evidence for the optimal time to wait to perform an ECG post-ROSC to reduce STEMI false positive rates. Chao-Wei Hwang, M.D., Ph.D. Johns Hopkins University School of Medicine Cardiac Cath Lab, Frederick Health Hospital