A recent study conducted in Japan suggests that individuals who have received a COVID-19 vaccine exhibit higher levels of a glucose analogue, indicating potential heart inflammation. The study compared 700 vaccinated individuals with 303 unvaccinated ones, all of whom showed no cardiac symptoms.
The research utilized positron emission tomography and computerized tomography (PET/CT) scans to analyze the uptake of fluorodeoxyglucose F18 (FDG), a glucose analogue that serves as an inflammation marker in the body.
Those who received Moderna or Pfizer vaccines demonstrated elevated FDG levels in the heart, liver, and spleen compared to the unvaccinated group.
This heightened FDG in the heart persisted across various factors, such as age, except for individuals tested more than 180 days post-vaccination. According to Dr. Takehiro Nakahara of Keio University School of Medicine, and co-authors, these increased FDG levels indicate heart inflammation.
They also noted that this inflammation might be minor, referencing a cardiac MRI study which suggested that post-vaccination heart issues were less severe than those resulting from COVID-19.
While the results are compelling, some aspects warrant consideration. The study did not include myocardial enzyme analysis or cardiac function testing. Additionally, researchers did not scrutinize the oncologic histories and treatments of the patient groups.
Dr. David Bluemke, editor emeritus of the journal and a radiology professor, emphasized that retrospective studies are more susceptible to bias due to unknown factors influencing who receives a vaccine.
Heart inflammation is a recognized side effect of Pfizer and Moderna vaccines, which can sometimes be serious. The most common symptom is chest pain, though none of the analyzed patients reported experiencing it. Some reported noncardiac symptoms like fever and a sore arm.
The study’s findings indicate that mild asymptomatic myocardial inflammation may be more prevalent than previously thought. This could potentially lead vaccine manufacturers to consider adjustments in their vaccines or delivery systems to mitigate inflammation.
Dr. Sanjay Verma, an American cardiologist, suggested that the increased FDG uptake in vaccinated patients implies a causal link between vaccination and heightened FDG levels. He emphasized the need for healthcare professionals to broaden their understanding of symptoms related to heart issues post-COVID-19 vaccination.
However, Dr. Andrew Bostom, a U.S. heart expert, and Dr. Verma both noted that the findings remain preliminary as there were no indications that the FDG levels led to health problems. Prospective follow-up studies would be necessary to ascertain if PET findings predict hospitalizations for heart-related issues.
The study retrospectively reviewed scans conducted between November 2020 and March 2022, including approximately 9,400 adult patients before exclusions. Some limitations include the retrospective nature of the study, emphasizing the need for a prospective study to validate the findings. The Pfizer and Moderna vaccines utilize mRNA technology.
The study was published by the Radiological Society of North America. Some authors disclosed grants from pharmaceutical companies, including Nihon Medi-Physics. The authors said they received no funding for the retrospective study.