(260) Severe Post-Stroke Complications: A Case of Heparin-Induced Thrombocytopenia and Thrombosis (HITT)

Introduction: Heparin, a widely used anticoagulant, can cause severe complications with prolonged use, including thrombocytopenia, bleeding, pulmonary embolism, and anaphylaxis. Heparin-induced thrombocytopenia (HIT), Type I, is a nonimmune form causing a transient platelet count drop within days of exposure, and HIT Type II (also known as HITT) is a rare but serious condition involving PF-IV-heparin complexes bound to IgG antibodies, leading to platelet activation and endothelial injury. Approximately 5% of heparin-exposed individuals develop HIT, with 50% resulting in thromboembolic events.

Description: A 69-year-old woman with a recent left pontine stroke, presented to the ED from an acute rehabilitation center, where she was receiving prophylactic subcutaneous heparin for 7 days, with sudden onset of shortness of breath. She was hypoxic with a platelet count of 56 k/µL, down from 205 k/µL at prior discharge and 131 k/µL two days earlier. En route from CT scan, she experienced agonal breathing and pulseless electrical activity (PEA) cardiac arrest with return of spontaneous circulation in 10 minutes. A CTA of the chest revealed saddle pulmonary emboli (PE) with right heart strain. She was initiated on heparin drip and vasopressors, transferred to the ICU, and started on VA-ECMO due to refractory shock. Suspected HITT (4T score of 8, high probability) led to switching from heparin to bivalirudin. She underwent thrombectomy, developed disseminated intravascular coagulation, had another PEA cardiac arrest, and ultimately passed after transitioning to comfort care.

Discussion: This case underscores the complexities of HIT/HITT and the necessity for high clinical suspicion. A drop in platelet counts during heparin use between 2 and 10 days post-exposure warrants immediate concern, especially in critically ill patients. Our patient, who received prophylactic subcutaneous heparin for 7 days prior to the diagnosis of PE, exemplifies this risk. Early 4T scoring is crucial for assessing HIT probability and guiding management, as patients may lack typical skin findings. Prompt recognition and immediate discontinuation of heparin, in favor of alternatives like bivalirudin, are vital to reduce the risk of catastrophic thromboembolic complications.