DISCUSSION
We previously reported 15 patients with clinically suspected SARS-CoV-2 mRNA vaccine induced myopericarditis. All patients had an abnormal CMR, with edema and or LGE in addition to clinical symptoms and troponin elevation, and some had abnormal ECG or echocardiogram [[3]
We have since established a clinical protocol for serial CMR performance in these patients consistent with the 2021 American Heart Association (AHA) statement that stressed the risk of sudden cardiac death, particularly with exercise, while active inflammation is present. [[6] our patients were restricted from exercise on discharge. Repeat CMR was performed within 3-6 months to guide next clinical decision-making steps; timing was modified in some individuals based on scanner accessibility and safety precautions during the COVID-19 pandemic. Although symptoms were transient and most patients appeared to respond to treatment (soley with NSAIDS), we demonstrated persistence of abnormal findings on CMR at follow up in most patients, albeit with improvement in extent of LGE.
CMR has increasingly been identified as an important diagnostic tool for myocarditis given its ability to identify subclinical injury and fibrosis by markers of LGE and edema. CMR also has been utilized in longitudinal follow up of patients with myocarditis to help therapeutic management, although exact screening protocols remain controversial[[6]
The presence of LGE is an indicator of cardiac injury and fibrosis and has been strongly associated with worse prognosis in patients with classical acute myocarditis. In a meta-analysis including 8 studies, Yang et al found that presence of LGE is a predictor of all cause death, cardiovascular death, cardiac transplant, rehospitalization, recurrent acute myocarditis and requirement for mechanical circulatory support[[5]
Similarly, Georgiopoulos et al found presence and extent of LGE to be a significant predictor of adverse cardiac outcomes in an 11 study meta-analysis[[7]
The persistence of LGE over time and its prognostic value is less well established. Malek et al found that in a cohort of 18 patients with myocarditis, nearly 70% had persistent CMR changes at a median follow-up time of 7 months[[5] Dubey et al found similar findings in their cohort of 12 pediatric patients, with persistence of LGE in all patients despite resolution of edema[[9] Prognostic meaning of LGE in vaccine associated myopericarditis requires further study.
Strain analysis by CMR also has been shown to have prognostic utility in myocarditis even in the setting of normal LV function[[10]
Strain testing can be performed without use of contrast material and can be particularly useful in situations where contrast administration is challenging or contraindicated. Notably, in our cohort, though there was significant reduction in LGE at follow up, abnormal strain persisted for the majority of patients at follow up.
This study has certain limitations. Patients who did not seek medical attention during acute illness or did not present with significant symptoms and require hospitalization were not captured, and their disease course may be different. Incomplete CMR data on other patients precludes extrapolation of our CMR findings to all who experienced mRNA vaccine-related myopericarditis. In addition, follow-up CMR timeframes varied from patient to patient making it difficult to predict the timing of CMR changes over time. the total number of patients reported is small, limiting ability to draw conclusions about the effect of treatment modalities or to generalize regarding outcomes of vaccine-associated myopericarditis.
In a cohort of adolescents with COVID-19 mRNA vaccine-related myopericarditis, a large portion have persistent LGE abnormalities, raising concerns for potential longer-term effects. Despite these persistent abnormalities, all patients had rapid clinical improvement and normalization of echocardiographic measures of systolic function. For patients with short acute illness, no dysfunction demonstrated by echocardiogram at presentation and resolution of symptoms at follow up, return to sports was guided by normalization of CMR alone. In patients with persistent CMR abnormalities we performed exercise stress testing prior to sports clearance per myocarditis recommendations[[6]
We plan to repeat CMR at 1 year post-vaccine for our cohort to assess for resolution or continued CMR changes.
The CDC notes that even though the absolute risk for myopericarditis following mRNA COVID-19 vaccine is small, the relative risk is higher for particular groups, including males 12-39 years of age. Some studies have suggested that increasing the interval between the first and second dose may reduce the incidence of myopericarditis in this population [[11] ] . These data led to an extension in CDC recommended dosing interval between dose 1 and dose 2 to 8 weeks. Further follow up assessment and larger multicenter studies are needed to determine the ultimate clinical significance of persistent CMR abnormalities in patients with post COVID-19 vaccine myopericarditis
Source:
https://www.jpeds.com/article/S0022-3476(22)00282-7/fulltext#secsectitle0025