Q: Which pericarditis does not usually presents with classic ST elevations on EKG

Answer: Uremic pericarditis

In Uremic Pericarditis, classic finding of diffuse ST elevations are rare; rather more commonly, non- specific repolarization changes are present. This is due to the relative lack of  epicardial electrical injury. Also, pericardial fluid  is enriched with  oppositely charged uremic molecules  which neutralizes the electrical gradient.