While the scientific statement, published in Circulation and endorsed by the Myocarditis Foundation, was developed before the COVID-19 pandemic started, the recommendations should be useful for suspected myocarditis following infection or vaccination, as cases have been reported primarily in teens and young adults, according to a press release with an additional statement from the AHA and its science leadership.
“Health care professionals should strongly consider inquiring about the timing of any recent COVID vaccination among patients presenting with symptoms related to cardiovascular conditions, as needed, in order to confirm the diagnosis and to provide appropriate treatment quickly,” the AHA stated.
Cardiologists are the ones to consult if myocarditis or any other heart-related condition is suspected in primary care, they added, echoing guidance from the CDC.
Nevertheless, the benefits of COVID-19 vaccination far outweigh the very rare risk of myocarditis and other adverse events, the organization argued. “We remain steadfast in our recommendation for all adults and children ages 12 and older in the U.S. to receive a COVID-19 vaccine as soon as they can receive it,” they wrote.
Overall, myocarditis lacks a universally accepted definition for both adults and children, which makes the gamut of clinical care and research more challenging.
The scientific statement by Yuk Law, MD, of Seattle Children’s Hospital, and colleagues recommended a comprehensive clinical assessment.
“Given the invasive and low-sensitivity nature of endomyocardial biopsy, its diagnostic focus shifted to a reliance on clinical suspicion,” they noted.
Clinical criteria aren’t enough to definitively confirm the diagnosis of myocarditis — that takes cardiac MRI (CMR) or biopsy — but a combination of clinical and laboratory features can upgrade a case from possible to clinically suspected, they said.
Myocarditis more often presents as a fulminant condition in children, with viral infection preceding it in about two-thirds of patients.
The most common symptoms are fatigue, shortness of breath, abdominal pain, and fever. Fever and arrhythmia are common at presentation. In COVID-19 vaccine-associated suspected myocarditis, chest pain is the primary symptom that has been reported.
The size of the patient, stability for transportation and sedation, technical capabilities at the treating center, and contraindications to gadolinium can help determine next steps on whether to go for CMR or biopsy.
Because acute cases can deteriorate rapidly, inpatient monitoring should be considered, especially continuous rhythm monitoring.
Early intervention with mechanical circulatory support can be lifesaving, so patients should be cared for at a pediatric center with expertise in its use and capable of transplantation, according to the statement.
Treatment often includes intravenous immunoglobulin and corticosteroids but should follow the etiology — whether it’s systemic autoimmune disease, Kawasaki disease, or COVID-linked multisystem inflammatory syndrome in children (MIS-C).
Once patients recover acutely, regular cardiology follow-up is recommended with echocardiography, electrocardiography, and laboratory testing every 1 to 3 months initially. Follow-up CMR or biopsy would be reasonable if other measures continue to be abnormal.
Because sudden death risk doesn’t necessarily disappear with normal systolic function after myocarditis, competitive sports should be avoided as long as active inflammation is present. After other measures normalize but no sooner than 3 to 6 months post-diagnosis, athletes should undergo 24-hour Holter monitoring and exercise stress testing before return to competition.
The authors expressed hope that the attention drawn to myocarditis by COVID-19 and by these guidelines would drive development of a universally accepted definition of myocarditis, without which progress in targeted therapy will continue to struggle.
“With improved cardiovascular diagnostic tools such as comprehensive viral PCR from tissue, biomarkers, immunohistochemistry, and CMR, formulating a set of criteria for its diagnosis based on the accuracy of testing from these studies should be top priority,” they concluded.