by Korea University College of Medicine

Subgroup analyses revealed significantly higher risk of thrombo-embolic events in patients with atrial fibrillation/flutter (AF/AFL) not receiving oral anticoagulants (OACs). COVID-19 vaccination is relatively safe for patients with AF/AFL, especially with concurrent OACs. Credit: Professor Jin Oh Na from Korea University College of Medicine

Development of the coronavirus disease 2019 (COVID-19) vaccine has been key to countering the pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Despite the current endemic status of COVID-19, patients with comorbidities and older adults remain vulnerable to severe illness and death due to COVID-19 infection. Therefore, medical agencies and organizations worldwide recommend COVID-19 vaccination, especially for individuals with an underlying disease.

However, several real-world studies have reported complications following COVID-19 vaccination such as thromboembolism—a health complication where circulating blood clots block the flow of blood to organs and bleeding events. Additionally, patients with atrial fibrillation/flutter (AF/AFL) are predisposed to higher risks of thrombo-embolic events.

To evaluate the risks of thromboembolism following COVID-19 vaccination in patients with AF/AFL, a collaborative team of researchers led by Professor Jin Oh Na from Korea University College of Medicine, and Professor Hyung-Kwan Kim from Seoul National university College of Medicine have conducted a self-controlled case series (SCCS) study. Their research findings were made available online on 12 July 2024 and was published in the European Heart Journal on August 21, 2024.

“Recent studies in France and UK have identified elevated risks of pulmonary embolism, acute myocardial infarction, and thrombo-embolic events after COVID-19 vaccination. Our findings are crucial for the development of future COVID-19 vaccine policies and treatment guidelines,” says Prof. Na, explaining the inspiration behind the present research.

Initially, the team of researchers utilized data from the National Health Insurance Service database of South Korea to include 124,127 patients with AF/AFL who received COVID-19 vaccine between February 2021 to December 2021. Subsequently, they measured the incidence of thrombo-embolic events, such as ischemic stroke and transient ischemic attack, within the 21-day risk period post-vaccination.

Preliminary analysis revealed that there was no increase in the risk of thrombo-embolic events following COVID-19 vaccination with an incidence rate ratio (IRR) of 0.93. To clarify whether the risks varied with respect to specific categories, Prof. Na and co-researchers conducted subgroup analyses. While the risks of thromboembolism did not vary with sex, age, or vaccine type, patients with AF/AFL who did not receive anticoagulant therapy after vaccination had a significantly increased IRR of 1.88.

“This finding underscores the necessity of anticoagulant therapy in real-world clinical practice, particularly for patients with AF/AFL following COVID-19 vaccination,” remarks Prof. Na.

Since the risk period of the current study was only 21 days post-vaccination, future research involving longer time-frames and booster doses of vaccine are needed to comprehensively understand the long-term complications associated with the COVID-19 vaccination.

“As the number of older adults in the high-risk category for cardiovascular disease rises, the need for COVID-19 vaccination in this demographic will also increase. The results of our study may therefore help in reducing the severe adverse effects like thromboembolism in such patients,” concludes Prof. Na, elaborating on the long-term implications of his research work.

Empowering safer vaccinations, this research offers a lifeline for protecting heart health in high-risk patients.

More information: You-Jung Choi et al, Thromboembolism after coronavirus disease 2019 vaccination in atrial fibrillation/flutter: a self-controlled case series study, European Heart Journal (2024). DOI: 10.1093/eurheartj/ehae335

Journal information:European Heart Journal

Provided by Korea University College of Medicine

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