A rare case of factor V inhibitor in a patient on amiodarone therapy

Factor V inhibitor is in itself a rare entity. We are reporting a case of an elderly male who presented with symptoms of bleeding and was later found to have developed factor V inhibitors. He had been on amiodarone for atrial fibrillation and developed hemorrhagic manifestations due to factor V inhibitors within a few months of initiating amiodarone therapy. Most of the cases of factor V inhibitors reported in the literature were found to be associated with exposure to bovine coagulation factors. However, in our case there was no evidence of bovine thrombin use during surgery. Furthermore, bovine thrombin-associated factor V inhibitors commonly emerge within 1-2 weeks after exposure during surgery versus several months later in our patient. There was dramatic improvement in the coagulation profile 6 weeks after discontinuation of amiodarone and institution of steroids and cyclophosphamide. We propose the consideration of amiodarone as a contributing agent in inhibitor generation even though a spontaneous development of factor V inhibitor could not be ruled out.