Cerebral venous thrombosis (CVT) due to vaccine-induced immune thrombotic thrombocytopenia (VITT) might have an in-hospital mortality rate of up to 50% but new thrombotic and bleeding events and deaths are rare after the acute phase, research shows.
International registry data on 60 patients who survived the acute phase of CVT after COVID-19 vaccination has shown only two patients (3%) died during follow-up – one due to a new intracerebral haemorrhage and one of unknown causes.
“No other relapses or bleeding events were reported. No new venous or arterial thrombotic events were reported in any patient,” the study said.
“Hospital readmission occurred in 9/54 (17%) cases, 4 of which were for a planned cranioplasty following decompressive hemicraniectomy.”
The study, published in Stroke [link here], said functional independence was achieved by 88% of patients at follow-up and 53% had returned to work or school.
And given the median follow-up was only five months, there was potential for even further recovery.
The study authors, including Clinical Associate Professor Tim Kleinig, Dr Alvin Chew, Dr Carlos Garcia-Esperon, Associate Professor Karl Ng, Dr Miriam Wronski, Dr Alvaro Cerera, Dr Jim Burrow and Dr Sophia Chatterton from Australia, said the high proportion of patients who were functionally independent at follow-up was comparable to that of patients after CVT not related to VITT.
“The low number of adverse outcomes in surviving CVT-VITT patients may be explained by the fact that anti-PF4 (platelet factor 4) antibodies, which cause VITT, are transient. With the disappearance of the anti-PF4 antibodies, the triggering factor for VITT may have resolved,” they said.
The study also found that where D-dimer levels were available in the registry data, they declined from >4 mg/L in the acute phase to ≤0.5 mg/L at follow-up in most (70%) patients.
Meanwhile, in a related article using data from the international CVT registry, mortality was lower in patients treated according to VITT recommendations compared to those not treated according to recommendations (32% v 52%; OR 0.43).