Patent Foramen Ovale-associated Stroke and COVID-19 Vaccination.

Background: COVID-19 infection has been associated with paradoxical thromboembolism through a patent foramen ovale (PFO) and ischaemic stroke. Such events have not been reported after COVID-19 vaccination. The aim of the present study was to investigate PFO-associated stroke during the mass COVID-19 vaccination in Slovenia. Methods: This prospective study, conducted between 26 December 2020 and 31 March 2022, enrolled consecutive patients (≥18 years) with PFO-associated stroke referred for a percutaneous closure to a single interventional facility in Slovenia. Results: A total of 953,546 people aged between 18 and 70 years received at least one dose of a COVID-19 vaccine approved by the European Medicines Agency. Of the 28 patients presenting with PFO-associated stroke, 12 patients (42.9%) were vaccinated prior to the event, of whom nine were women and three were men, aged between 21 and 70 years. Stroke occurred within 35 days after vaccination in six patients (50%). Clinical presentation included motor dysphasia, paresis, vertigo, ataxia, paraesthesia, headache, diplopia and hemianopia. At hospital discharge, 11 patients (91.6%) had at least one residual ischaemic lesion. Conclusion: A temporal coincidence of COVID-19 vaccination and PFO-associated stroke has been described. A potential cause-effect relationship may only be hypothesised.