C42-46 The Bleeding Never Ends: A Superwarfarin Story

Introduction Superwarfarins are 2nd-generation Vitamin K antagonists that are 100x more potent than Warfarin. They have 10-50x longer half-life than warfarin, with effects lasting upto 6 months. They cause significant bleeding, with most common sites being urine, retroperitoneum, alveoli, GI and intracranial. Case Presentation We present a 65-year-old male farmer with history of interstitial lung disease, major depressive disorder, and methamphetamine use disorder, who presented with hemoptysis and dyspnea for 1 day. On arrival, he was in severe respiratory distress prompting intubation. He was found to have copious blood in the oropharynx. Laboratory evaluation revealed acute anemia (hemoglobin 9 g/dL), elevated INR (7.01), prolonged PT (78 s) and PTT (67 s). Urine drug screen was positive for methamphetamine. Chest imaging showed bilateral interstitial fibrosis with superimposed right-lower lobe perihilar pneumonitis suggesting pulmonary edema vs pneumonitis. Bronchoscopy revealed progressively bloody serial aliquots and incremental RBC counts, consistent with diffuse alveolar hemorrhage. Thromboelastogram showed prolonged clotting (R) time (>17 minutes) and maximum amplitude. Peripheral smear revealed normochromic, normocytic anemia. Rheumatological workup including ANCA panel, anti-GBM, cryoglobulin antibodies and infectious workup including bacterial, viral, tick-borne and fungal etiologies were unrevealing. Coagulation factor levels found isolated factor X deficiency (<10%). On further questioning, the patient’s wife reported exposure to rat poison as pesticide, with Brodifacoum (superwarfarin) listed as the main ingredient. Throughout hospitalization, the patient remained on maximal ventilatory support. He received multiple blood products including 4-factor PCC, FFP, pRBCs, daily tranexamic acid nebulization, and broad-spectrum IV antibiotics without improvement in coagulation profile or respiratory status. He was given high-dose IV Vitamin K upto 200 mg/day with goal to continue for 6 months, and pulse-dose IV steroids followed by prednisone taper. Despite aggressive measures for 2 weeks, patient failed to improve. He was subsequently transitioned to comfort measures and expired. Discussion Superwarfarin toxicity is poorly understood. It is found in rodenticides and pesticides. Treatment includes discontinuing toxin exposure and prolonged course of high-dose Vitamin K. There is limited benefit to giving blood products like 4-factor PCC or FFP, given the long half-life of superwarfarin. It is peculiar that this patient had isolated factor X deficiency with normal factor VII levels, which is the first factor to diminish in warfarin overdose. Differential diagnoses include acquired factor X deficiency from AL amyloidosis. Although patient had no other identifiable features of amyloidosis, a mixing study could have helped identify if acquired factor deficiency were present.