Fatal Acute Intestinal Infarction Following Abrupt Dabigatran Withdrawal in Unrecognized Masked Polycythaemia Vera: Rebound Vascular Risk, Corporate Opacity, and Clinical Trial Safety Governance

Background: Direct oral anticoagulant (DOAC) withdrawal carries a known risk of prothrombotic rebound, but its impact in unrecognized myeloproliferative neoplasms (MPNs) is under-reported. Objectives: To evaluate a fatal adverse drug reaction (ADR) following dabigatran withdrawal in a participant with unrecognized Masked Polycythaemia Vera (mPV) enrolled in the RE-SONATE trial (BI 1160.63), and assess associated trial safety governance failures. Case Presentation & Safety Data: A 69-year-old male with recurrent mixed arterial-venous thrombosis was enrolled in the RE-SONATE trial. Warfarin was abruptly stopped upon entry. At the end-of-treatment visit on July 27, 2009, laboratory testing revealed severe hyperviscosity: hemoglobin 19.5 g/dL, hematocrit 56.9%, platelets 493,000/μL, and PCT 0.51%. Investigators performed no therapeutic phlebotomy or anticoagulant safety bridging and discharged the participant. Eighteen days post-trial, the patient suffered fatal acute mesenteric infarction. Post-mortem molecular testing confirmed the JAK2 V617F mutation. Global WHO VigiAccess data corroborate this hazard, with ~5% of dabigatran ADRs involving haematological/hyperviscosity disorders. Discussion & Governance: Discharging a participant with extreme hyperviscosity directly violated ICH-GCP E6 and European LeukemiaNet guidelines. Furthermore, the sponsor's ongoing refusal to disclose unblinded trial records (eCRF) or insurance conditions mirrors historical criticisms of withheld trial safety data. Conclusions: Unbridged DOAC withdrawal in unrecognized mPV precipitates fatal thrombosis. Trial safety protocols must enforce mandatory MPN screening and post-trial data transparency.