Case Report: Heparin resistance as the harbinger of heparin-induced thrombocytopenia in acute pulmonary embolism

The case involves a 50-year-old man with acute pulmonary embolism who received high-dose unfractionated heparin up to 1,850 units per hour. Despite dose escalation, the patient showed no expected anticoagulant response, a condition called heparin resistance. During treatment, he experienced two episodes of hemodynamic instability requiring rescue thrombolysis. On day 8 of heparin therapy, thrombocytopenia with platelet count of 104 × 10⁹/L and a high 4Ts score (6 points) led to suspicion of heparin-induced thrombocytopenia. Heparin was immediately replaced with argatroban, which achieved the target anticoagulant response. The diagnosis was confirmed by positive anti-platelet factor 4/heparin antibodies. After platelet recovery, the patient was switched to oral rivaroxaban. Follow-up examinations at discharge and 3 months showed significant improvement with normalized cardiac function.