Delayed-Onset Heparin-Induced Thrombocytopenia Following Aortic Valve Replacement / 日本心臓血管外科学会雑誌

ABSTRACT

Some 50% of patients who undergo cardiac surgery will have heparin-induced thrombocytopenia (HIT) antibodies, only 1% will develop typical clinical HIT. Especially delayed-onset HIT is not well-known and extremely rare. A 83-year-old man underwent aortic valve replacement (AVR) with a bioprosthetic valve (Mitroflow 21 mm) and pulmonary vein isolation (PVI). Intravenous unfractionated heparin (8,000 I.U./day) was administered for 5 days after surgery. He had a good recovery and was discharged to home with a platelet count of 100,600/μl on POD 15 on warfarin. On POD 18, he was readmitted to our hospital due to cerebral infarction with hemiparesis. As MRI revealed a multiple left hemispheric infarction, the presence of cardiogenic cerebral infarction was suspected. Continuous intravenous administration of unfractionated heparin (15,000 I.U./day) was started. On POD 24, the platelet count fell to 27,000/μl, and a contrast CT scan revealed a giant thrombus in the aortic arch. He was found to have HIT antibodies, supporting a diagnosis of HIT. After cessation of heparin therapy and administration of vitamin K antagonist, argatroban was administered. He recovered neurologically and was discharged on POD 58. He remains well at 3 years follow up. If a patient has an unexplained and severe thrombocytopenia after cardiovascular surgery, delayed-onset HIT should be taken into consideration.