The aim of this prospective study by Canadian authors was to investigate possible cardiac sequelae of anti-SARS-CoV-2 vaccination in participants who met diagnostic criteria for acute myocarditis early after anti-SARS-CoV-2 vaccination. They evaluated the alterations of myocardial tissue with fluorine 18 fluorodeoxyglucose (FDG) PET and magnetic resonance imaging (MRI), several circulating biomarkers of cardiac injury and systemic inflammation, and adverse cardiac outcomes. PET and MRI visualization of myocardial tissue showed that localized myocardial inflammation and edema was present in a small proportion of patients with symptomatic myocarditis at approximately two months after anti-SARS-CoV-2 vaccination.
Various adverse events have been reported following anti-SARS-CoV-2 vaccination, including myocarditis and pericarditis. Previous studies showed an association between a myocardial injury and elevated circulating levels of the free full-length SARS-CoV-2 spike protein, which evades antibody recognition. https://discovermednews.com/elevated-circulating-levels-of-free-full-length-spike-protein-not-bound-by-antibodies-in-adolescents-and-young-adults-with-myocarditis-after-sars-cov-2-mrna-vaccination/
Cardiac MRI is important for assessing alterations in myocardial tissue, while cardiac FDG PET provides complementary physiological information about changes in myocardial metabolism.
About the study
This prospective cohort study was registered at ClinicalTrials.gov (NCT04967807) before the first participant was enrolled.
The study involved 54 participants aged 17 years or older who had been vaccinated against COVID-19. The participants were divided into three groups. The first group included 17 participants with new cardiac symptoms within 14 days of vaccination who met diagnostic criteria for acute myocarditis (symptomatic myocarditis). The second group included 17 participants with new cardiac symptoms who did not meet criteria for myocarditis (symptomatic without myocarditis). The third group included 20 participants who did not have cardiac symptoms within 14 days of vaccination and did not meet diagnostic criteria for acute myocarditis (asymptomatic).
The diagnostic criteria for acute myocarditis following anti-SARS-CoV-2 vaccination were: 1. the onset of symptoms within 14 days of vaccine administration without any other identified cause, 2 fulfillment of clinical presentation and diagnostic testing criteria for clinically suspected myocarditis, proposed by the European Society of Cardiology, and 3. fulfillment of the diagnostic criteria for myocarditis following anti-SARS-CoV-2 vaccination, proposed by the Center for Disease Control and Prevention. In patients with symptomatic myocarditis, 4 of 17 patients met probable criteria, whereas 13 of 17 participants met confirmed criteria for myocarditis at baseline.
The onset of myocarditis followed the administration of mRNA-1273 (Moderna) in nine patients (53%) and BNT162b2 (Pfizer-BioNTech) in eight patients (47%). Eleven patients had been admitted to the hospital after vaccination, and the median length of stay was 3 days. Five of them had been treated with anti-inflammatory therapy that had been stopped at least two weeks before the research visit.
Researchers also evaluated adverse outcomes after anti-SARS-CoV-2 vaccination, such as resuscitated sudden cardiac death, new-onset sustained atrial or ventricular arrhythmia, stroke, myocardial infarction, or heart failure that required medical care.
On the same day, approximately two months after anti-SARS-CoV-2 vaccination, all participants had cardiac PET and MRI, 12-lead electrocardiography (ECG) and clinical evaluation. In addition, circulating levels of interleukin 6, interleukin 8, high-sensitivity C-reactive protein, myeloperoxidase, high-sensitivity troponin I, and B-type natriuretic peptide were assessed.
At two months follow-up, in a small proportion of participants with acute myocarditis after vaccination had persistent myocardial inflammation and edema. This was detected by focal FDG uptake at PET (2 of 17 participants) and high T2 signal intensity on MRI (3 of 17 participants). In patients with symptomatic myocarditis, the level of high-sensitivity troponin I decreased significantly at follow-up in comparison to peak values found early after vaccination.
Additionally, one of 17 participants with symptomatic myocarditis had abnormal ECG findings with T-wave changes. Other ECG parameters or circulating blood biomarkers did not differ between the groups. None of the participants experienced adverse cardiac events beyond myocarditis, including myocardial edema or pericardial enhancement.
In conclusion, PET and MRI visualization of myocardial tissue showed that localized myocardial inflammation and edema was present in a small proportion of patients with symptomatic myocarditis at approximately two months after anti-SARS-CoV-2 vaccination. According to the authors, it is possible that more participants might have had focal FDG uptake or other cardiovascular abnormalities if they had been imaged sooner after vaccination.
This study demonstrated low rates of adverse events in patients with myocarditis after anti-SARS-CoV-2 vaccination. However, given the association of myocardial fibrosis with arrhythmias and major adverse cardiac events, the authors suggested that long-term follow-up is needed, especially in patients with persistent late gadolinium enhancement on MRI.
The study was published in Radiology: Cardiothoracic Imaging.
Marschner CA. et al. Myocardial Inflammation at FDG PET/MRI and Clinical Outcomes in Symptomatic and Asymptomatic Participants after COVID-19 Vaccination. Radiology: Cardiothoracic Imaging 2023; 5(2):e220247. Published Online:Mar 9 2023 (Open Access) https://doi.org/10.1148/ryct.220247