An Australian case series of vaccine-induced thrombotic thrombocytopenia (VITT) following first ChAdOx1 COVID-19 vaccinations highlights the fact that the presentation can include arterial thrombosis in addition to venous involvement.
The case series, published in BMJ Neurology Open, comprised three women in their 50-60s.
Two women developed severe headaches within 7-10 days of vaccination which progressed to right-sided weakness in one case and reduced level of consciousness in the other. The third woman presented to hospital with convulsive status epilepticus 10 days after vaccination.
In Case 1, a CT demonstrated an extensive left common carotid thrombus extending into the left internal carotid artery (ICA) with a large penumbra of the left middle cerebral artery territory.
“The patient was administered intravenous alteplase and transferred for emergency endovascular clot retrieval. En route, the patient was found to have marked thrombocytopenia (platelet count 40×109/L), an elevated D-dimer of 8.55 mg/L (normal <0.50 mg/L) and fibrinogen level at the lower limit of normal (2.1 g/L, reference 2–4 g/L). Thrombolysis was promptly ceased given the severe thrombocytopenia and she underwent endovascular clot retrieval with excellent angiographic result.”
CT in Case 2 demonstrated extensive right-sided temporal lobe haemorrhage with mass effect.
The patient underwent an emergency right-sided decompressive craniectomy and temporal intracranial haemorrhage removal.
In Case 3, CT brain and venogram demonstrated extensive CVST with a large left temporo-occipital haemorrhagic transformation of a venous infarct with a mild degree of midline shift and transtentorial herniation
After transfer from a regional hospital, cerebral angiography demonstrated complete occlusion of the left ICA from the cervical segment, non-occlusive thrombus within the proximal right ICA and extensive CVST. She went on to thrombectomy.
The report said the complication with arterial thrombosis causing stroke posed special difficulties in acute management.
“Thrombolysis is often given in the emergent patient with a neurological deficit, often well before blood results have demonstrated the characteristic abnormalities.”
“However, vigilance is warranted in these situations with an awareness of the possibility of VITT, as thrombocytopenia, especially if it is significant, is a contraindication to thrombolysis. Nevertheless, in certain other scenarios, such therapy is warranted, as in massive pulmonary embolism with circulatory compromise.”
The authors said endovascular clot retrieval, if possible for large vessel occlusive stroke, is preferred but still poses threats given the bleeding and rethrombosis risk.
They said that while the arterial involvement may be severe in cases, the increased risk of arterial thromboembolic events with VITT appears to remain much lower than the rate of arterial thrombosis seen with COVID-19 infection.
Vaccination with ChAdOx1 nCoV-19 should still be considered, taking into account the likelihood of COVID-19 infection as well as other available vaccine types and their inherent risks in the community, they said.