Acute pulmonary thromboembolism after messenger RNA vaccination against coronavirus disease 2019: A case report

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is defined as thrombosis after inoculation of adenovirus vector vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). VITT rarely occurs with messenger RNA vaccines, and the use of heparin for VITT is also controversial. A 74-year-old female patient with no risk factors for thrombosis was brought to our hospital after loss of consciousness. Nine days before admission, she had received the third vaccine against SARS-CoV-2 (mRNA1273, Moderna). Immediately after transport, cardiopulmonary arrest occurred, prompting extracorporeal membrane oxygenation (ECMO). Pulmonary angiography showed translucent images of both pulmonary arteries, resulting in the diagnosis of acute pulmonary thromboembolism. Unfractionated heparin was administered, but D-dimer subsequently became negative. Pulmonary thrombosis remained in large volume, indicating that heparin was ineffective. Treatment was shifted to anticoagulant therapy using argatroban, which increased D-dimer level and improved respiratory status. The patient was successfully weaned from ECMO and ventilator. Anti-platelet factor 4 antibody examined after treatment initiation showed negative results; however, VITT was considered as an underlying condition because of the time of onset after vaccination, the ineffectiveness of heparin, and the absence of other causes of thrombosis. In case heparin is not effective, argatroban can be an alternative therapy against thrombosis. LEARNING OBJECTIVE: During the coronavirus disease 2019 pandemic, treatment with vaccine against severe acute respiratory syndrome coronavirus 2 has been widely performed. Vaccine-induced immune thrombotic thrombocytopenia is the most common thrombosis after adenovirus vector vaccines. However, thrombosis can also occur after messenger RNA vaccination. Though commonly used for thrombosis, heparin may be ineffective. Non-heparin anticoagulants should be considered.