The authors from Hong Kong, China, studied the outcome of COVID-19 vaccine–associated myocarditis in adolescents up to one 1 after diagnosis. The global systolic ventricular function appeared to be preserved. However, impaired left ventricular and right ventricular myocardial deformation and the persistent late gadolinium enhancement were found in a significant subset of patients.
Myocarditis has been identified as a side effect of COVID-19 mRNA vaccinations, especially in adolescent and young adult male patients. In the majority of the young patients, the short-term clinical trajectory shows a resolution of cardiac symptoms and normalization of left ventricular ejection fraction. Some previous data showed myocardial tissue sequlae (myocardial inflammation and edema) in a small proportion of symptomatic adolescents with COVID-19 vaccine–associated myocarditis at approximately 2 months after vaccination. https://discovermednews.com/pet-and-mri-visualization-of-myocardial-tissue-sequlae-in-17-patients-with-myocarditis-after-covid-19-vaccination/
However, the long-term cardiovascular outcomes following COVID-19 vaccine–associated myocarditis remain unclear.
About the study
The researchers assessed the cardiac outcome of COVID-19 vaccine–associated myocarditis in adolescents up to one 1 after diagnosis. The findings of the electrocardiogram, echocardiogram, and cardiac magnetic resonance imaging at diagnosis were thoroughly examined. The clinical assessment, electrocardiogram, echocardiogram, and cardiac magnetic resonance imaging were performed at latest follow-up too.
The study included forty patients (33 male), 15.1±1.6 years of age (range 12.7–17.9). They were followed for a period of 10.0±1.3 months (range, 5.6–12.3), representing all cases identified in Hong Kong during the period of study. Twenty-nine patients (73%) were asymptomatic, 7 patients (18%) reported noncardiac chest pain, 3 patients (8%) reported palpitations, and 1 patient (3%) reported fatigue during follow-up. There were no patients diagnosed with cardiac arrhythmias, angina pectoris, or heart failure.
The electrocardiogram revealed abnormal results, with ST-segment or T-wave abnormalities in 31 patients (78%) at presentation. However, all patients had normalized electrocardiogram at the latest follow-up.
At presentation, the echocardiogram showed that the left ventricular ejection fraction was normal in all patients. However, mild increased echogenicity of the pericardium or left ventricular lateral wall in 6 patients (15%), and minimal (<2 mm) pericardial effusion in 2 patients (5%) were found.
At the latest follow-up, the echocardiogram showed normal left ventricular ejection fraction in 38 patients (95%), while 2 patients (5%) had borderline left ventricular ejection fraction of 51.1% and 53.6%. All patients had normal right ventricular fractional area change.
The LV 4-chamber longitudinal, global longitudinal, and circumferential systolic strain was impaired (Z score <–2) in 8 (22%), 7 (20%), and 4 (11%) patients, respectively. The right ventricular longitudinal systolic strain and early- and late-diastolic strain rates were impaired in 2 (6%), 3 (8%), and 10 (28%) patients, respectively. The mean Z scores of the diastolic functional indices of both ventricles were significantly lower than zero. There were no patients with coronary abnormalities.
At the time of presentation, 39 patients had cardiac magnetic resonance imaging, and 26 of them had abnormal findings. These findings included features of myocarditis in 22 patients (56%), abnormal T1 values in 21 patients (54%), abnormal T2 values in 24 patients (62%), late gadolinium enhancement in 19 patients (49%), and reduced left ventricular ejection fraction in 7 patients (18%).
In 26 patients who had initial abnormal findings on cardiac magnetic resonance imaging, follow-up cardiac magnetic resonance imaging was done. The findings revealed mild residual late gadolinium enhancement in 15 patients (58%), borderline left ventricular ejection fraction in 2 patients (8%), and normal findings in 11 patients (42%). No one of these patients had abnormal T1 values or features of myocarditis.
The distribution of late gadolinium enhancement in the 16 patients shows a predilection for involvement of the lateral segments. The presence of late gadolinium enhancement at diagnosis was found to be correlated with the presence of late gadolinium enhancement on follow-up. Patients with (n=16) and without (n=11) late gadolinium enhancement on follow-up cardiac magnetic resonance imaging had similar echocardiographic parameters.
The authors emphasized that this study is, to their knowledge, the longest follow-up study of the cardiac outcome of vaccine–associated myocarditis in adolescents. The results showed that the global systolic ventricular function appears to be preserved. However, comprehensive cardiac evaluation and imaging revealed impairment of left ventricular and right ventricular myocardial deformation and persistence of late gadolinium enhancement in a significant subset of patients with up to 1 year of follow-up.
The authors pointed to previous short-term study which reported abnormal cardiac magnetic resonance-derived left ventricular longitudinal strain and late gadolinium enhancement in 70% to 75% of adolescents with COVID-19 vaccine–associated myocarditis followed up for 3 to 8 months.
The researchers concluded that the implications of impaired systolic and diastolic myocardial deformation and late gadolinium enhancement found in this study remain unclear. They stated that impaired myocardial deformation and persistent late gadolinium enhancement are indicators of subclinical myocardial dysfunction and fibrosis. Hence, the authors assert that, there is a potential long-term effect on exercise capacity and cardiac functional reserve during stress.
This article was published in Circulation.
Journal Reference
Kwong-man Yu C et al. Cardiovascular Assessment up to One Year After COVID-19 Vaccine–Associated Myocarditis. Circulation. 2023;148:436–439. Published online 2023 Aug 1 (Open Access) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10373639/