Abstract Introduction Acquired hemophilia A (AHA) is a rare condition caused by autoantibodies against factor VIII (FVIII), leading to severe bleeding. While spontaneous hemorrhage is common, pericardial effusion and tamponade due to FVIII inhibitors are exceptionally rare. This case highlights a patient with FVIII inhibitor-induced pericardial effusion progressing to tamponade and obstructive shock, emphasizing diagnostic work-up and incidence. Case Presentation A 75-year-old male with a history of COPD, ulcerative colitis, atrial fibrillation, and remote pacemaker placement presented with hypotension and dyspnea. Physical exam revealed hypotension (BP 60/30 mmHg) and muffled heart sounds. Echocardiogram confirmed a large pericardial effusion with tamponade physiology. Emergent pericardiocentesis drained 710 mL of frank bloody fluid, improving the shock state.Lab findings showed prolonged aPTT (50.1 sec), which failed to correct on mixing study, low FVIII activity (14%), and a FVIII inhibitor titer of 7.8 Bethesda units. Hematology consultation agreed with the diagnosis of AHA. Initial management included fresh frozen plasma and DDAVP while awaiting further confirmatory labs, followed by IVIg, methylprednisolone, and recombinant activated factor VII (rFVIIa) for hemostasis. The patient stabilized with recombinant FVIII and immunosuppressive therapy. Repeat echocardiography confirmed resolution of effusion. Discussion AHA has an incidence of 1.5 cases per million per year, mostly affecting older adults. While soft tissue and mucosal bleeding are typical, hemorrhagic pericardial effusion and tamponade are exceedingly rare.Diagnosis relies on prolonged aPTT uncorrected by mixing studies, low FVIII activity, and elevated FVIII inhibitor titers. Management includes hemostatic agents (e.g., rFVIIa, activated prothrombin complex concentrates) and immunosuppression.In this case, hemorrhagic pericardial effusion directly led to tamponade and obstructive shock, highlighting the need for early recognition. Prompt pericardiocentesis, coagulation studies, and targeted treatment were essential for stabilization. Conclusions This case underscores the rare but life-threatening manifestation of FVIII inhibitor-induced pericardial effusion and tamponade. Clinicians must consider AHA in patients with unexplained hemorrhagic effusions and prolonged aPTT to enable timely intervention. This abstract is funded by: N/a
Graumann et al. (Fri,) studied this question.