The Latest on COVID-19 and the Heart in Children

William T. Basco, Jr, MD, MS


May 31, 2022

The 2022 Pediatric Academic Societies meeting included an excellent session by Dr Michael R. Carr on the acute and delayed effects of COVID-19 on children's hearts. Data on the risk for cardiac injury during acute COVID-19, return-to-play guidelines after COVID-19–related heart injury, and postvaccine-associated myocarditis were reviewed.

COVID-Induced Cardiac Injury

The risk for COVID-induced cardiac injury is directly associated with age. Recent Centers for Disease Control and Prevention data revealed a "myocarditis or pericarditis" rate in the range of 12-17 cases per 100,000 SARS-CoV-2 infections among male children aged 5-11 years (lower rates for females); the rate jumps to 50-65 cases per 100,000 infections among male children aged 12-17 years. So cardiac injury due to acute COVID-19 appears rare, but the risk is clearly associated with male sex and adolescent age.

Return to Play After COVID-19

Clinicians may be pressed by patients and parents for advice on return to play after illness with COVID-19. In July 2020, the American College of Cardiology published an algorithm that has been adjusted over time, most recently in 2022 by the American Academy of Pediatrics. These algorithms stratify recommendations by degree of illness. One rule of thumb: Patients with severe COVID-19 (ICU care or multisystem inflammatory syndrome in children [MIS-C]) have only one box on the algorithm, and that is to rest for 3-6 months and only return to usual activity after cardiac clearance. Moderate disease (defined as ≥ 4 days of fever > 100.4 °F; ≥ 1 week of myalgia, chills, lethargy, or any non-ICU hospital stay; and no evidence of MIS-C) require undergoing an ECG to look for cardiac dysfunction, followed by at least 10 days of rest if the ECG is negative or referral for cardiac evaluation if either ECG or exam by a pediatric cardiologist is abnormal.

Clinicians can perhaps be more permissible with patients who are younger or who have had less severe disease. For example, if a patient younger than 12 years of age is asymptomatic with routine activity at the time of evaluation, an ECG is not indicated. For patients aged 12-15 years who are asymptomatic at the time of evaluation but participate in a high-intensity sport, clinicians might consider obtaining an ECG. As few as 3 days of rest might be enough for select patients who are asymptomatic at presentation. For other patients, clinicians should work with parents to introduce activity gradually and make it clear to parents that any activity intolerance requires quick reevaluation. On existing athlete registries, no deaths that are attributable to post–COVID-19 cardiac effects have been confirmed in children; however, all data presented during the session were from prior to the Omicron variant surge in early 2022, so more information may be forthcoming.

Considerations For MIS-C

Among children experiencing MIS-C, 35% had ECG changes, 40% exhibited left ventricular systolic or diastolic dysfunction, and 30% had mitral regurgitation, meaning that a large percentage of patients with MIS-C show some degree of cardiac dysfunction. Unfortunately, we are still in the data-gathering phase for long-term outcomes. Functional parameters tend to improve within a week, and most patients will return to normal cardiac function by 3-4 months.

Return to play after MIS-C is quite different from that for acute COVID-19. Patients with MIS-C should be treated much like other patients with myocarditis with an expected return to play in 3-6 months and only after cardiac follow-up. Another good-to-remember recommendation is to delay COVID-19 vaccination for at least 90 days after an episode of MIS-C.

Vaccine-Related Myocarditis

Once again, older age appears to be a risk factor because most patients with postvaccine myocarditis have been in their mid-teens to early 20s, with events more likely after the second vaccine dose and also more likely in male children (4:1 ratio to female children). No deaths have occurred from postvaccination myocarditis in patients younger than 30 years. Still, many individuals have exhibited residual MRI enhancement in the cardiac tissue for some time after experiencing postvaccination myocarditis; it's currently unclear whether that has clinical implications. By comparison, a recent CDC publication demonstrates convincingly that the risk for cardiac effects is much greater after acute COVID-19 than after COVID-19 vaccination, with risk ratios often higher than 20, depending on age and condition (eg, myocarditis vs pericarditis). Data are still insufficient to determine whether clinicians should recommend or avoid COVID-19 vaccination in children with congenital heart disease.

In summary, administering COVID-19 vaccines requires a great deal of shared decision-making with parents, and the clinician's role is to educate parents about all potential risks related to both the vaccine and COVID-19 illness. Research has consistently shown that acute COVID-19 myocarditis and myocarditis associated with MIS-C are much more likely to occur in unvaccinated youth and more likely than postvaccination myocarditis, regardless of age.

William T. Basco, Jr, MD, MS, is a professor of pediatrics at the Medical University of South Carolina and director of the Division of General Pediatrics. He is an active health services researcher and has published more than 60 manuscripts in the peer-reviewed literature.

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