Thrombotic thrombocytopenic purpura following coronary artery bypass graft surgery: prospective observations of an emerging syndrome.

Thrombotic thrombocytopenic purpura (TTP) is a rapidly progressive syndrome of thrombocytopenia, microangiopathic hemolysis, and organ dysfunction. While most TTP is idiopathic, we have observed four cases following coronary artery bypass graft (CABG) surgery in a 2-year period. We have studied these cases prospectively to define the natural history, and potentially unique characteristics, of a post-CABG TTP syndrome. On average, the onset occurred 4.75 days postoperatively (post-op), but the diagnosis was made 8.5 days post-op. All four patients exhibited microangiopathic hemolysis, thrombocytopenia, mental status changes, and severe renal failure. Three also had unexplained fever. All patients received therapeutic plasma exchange for 5, 6, 8, and 11 days, respectively, and all achieved complete hematological remission. Three patients required dialysis for 7, 15, and 16 days, respectively, but were restored to baseline renal function if they survived. One patient with severe pre-existing peripheral vascular disease died of Candida sepsis. None of the surviving patients have relapsed at a median follow-up of 19 months. These cases appear distinguished by a delay in diagnosis despite intensive medical supervision, a florid presentation with most, or all, of the components of the classic TTP pentad, an excellent and rapid response to plasma exchange, and a tendency not to relapse. As such, they may represent a subgroup characterized by a more rapid and severe onset, but also a rapid response to therapy and earlier recovery than the typical idiopathic form of TTP. An aggressive approach to management is warranted.