Heart Function Recovers Quickly in Adolescents with COVID-19-Related MIS-C

Anirban Banerjee, MD

A new study from the Children’s Hospital of Philadelphia is providing clinicians with insight into the cardiovascular outcomes of children recovering from COVID-19-related multisystem inflammatory syndrome (MIS-C).

Results of the study, which was a retrospective, longitudinal cohort study of 60 controls and 60 cases of MIS-C in children, suggest heart function of these patients typically improves within the first week with gradual improvement until complete normalization by 3 months, with no evidence MIS-C caused lasting coronary artery abnormalities and no subclinical cardiac dysfunction after 3 months.

“These results have important implications for our health care teams managing care for children with MIS-C. Our findings may also provide guidance for a gradual return to playing sports after cardiac clearance three to four months later. Tests needed for clearance include electrocardiogram and echocardiogram. We also recommend cardiac MRI for children who have highly abnormal baseline cardiac MRI during the acute stage or show evidence of continued severe left ventricle dysfunction,” said senior investigator Anirban Banerjee, MD, a professor of clinical pediatrics at the University of Pennsylvania Perelman School of Medicine and an attending cardiologist with the Cardiac Center at the Children’s Hospital of Philadelphia, in a statement.

As the COVID-19 pandemic has continued into its second year, the impact of COVID-19-related MIS-C in children has become a focus of research among cardiologists and pediatricians alike. Citing a lack of consensus related to management strategies and recommendations for returning to sports, Banerjee and a team of colleagues at the Children’s Hospital of Philadelphia designed a retrospective, longitudinal cohort study to determine the short-term impact of acute myocardial injury caused by MIS-C through using data from patients aged 18 years or younger admitted to the hospital or its affiliate institution from April 2020-January 2021.

For the purpose of analysis, investigators retrospectively assessed transthoracic echocardiograms during initial hospitalization (acute phase), within 1 week of the first echocardiogram (subacute phase), at 1-month follow-up, and at the 3-4-month follow-up. Investigators defined the subacute phase as the period after the complete withdrawal of all vasoactive-inotropic support during the hospitalization. The primary outcomes of interest included strain parameters, such as global longitudinal strain, early diastolic strain rate, right ventricular free wall strain, and left atrial strain.

Investigators identified a cohort of 60 controls and 60 cases of MIS-C in children. Of the 60 with MIS-C, 60 had data related to echocardiograms from the acute phase, 50 had data from follow-up in the subacute phase, 39 had data from the 1-month follow-up, and 25 had data from the 3- to 4-month follow-up. The median follow-up in the subacute phase occurred 3 days after initial echocardiography, the median time for the 1-month follow-up was 22 days after initial echocardiography, and the 3- to 4-month follow-up occurred at a median of 91 days.

The mean age of patients with MIS-C was 10.0±4.3 years and 60% were male. Controls had a mean age of 11.5±3.9 years and 55% were men.

Of the 60 patients with MIS-C, almost all patients received treatment with intravenous immunoglobulin (92%) and/or systemic steroids (90%). Myocardial injury was identified in 42 patients at the time of prevention, with 6 presenting with isolated elevated BNP, 13 presenting with isolated elevated troponin, and 23 presenting with elevation of both.

Upon analysis, investigators found recovery occurred within the first week for all deformation parameters, including left ventricular global longitudinal strain, peak left atrial strain, longitudinal early diastolic strain rate, and right ventricular free wall strain. Investigators pointed out this improvement continued beyond the first week and complete normalization occurred by 3 months.

Further analysis indicated the media time to normalization of both global longitudinal strain and left atrial strain was 6 days (95% CI, 3-9). Additionally, results suggested myocardial injury at presentation did not impact short-term outcomes. Investigators noted 7% of patients had small coronary aneurysms at presentation, all of which resolved, and only 1 of 9 patients had residual edema but no fibrosis by cardiac magnetic resonance imaging.

“This study provides additional evidence that myocardial involvement is transient and may not lead to long-term abnormalities in left ventricular diastolic or systolic function,” added Kevin G. Friedman, MD, a member of the American Heart Association’s Young Hearts Council and the AHA’s Rheumatic Fever, Endocarditis and Kawasaki Disease Committee, in the aforementioned statement. “Although cardiac involvement in the acute stage of illness is common, it is reassuring that all patients recovered normal cardiac function within about one week. This data tells us that, fortunately, lasting heart injury is very uncommon in MIS-C. Even in those patients with significant cardiac abnormalities in the acute phase of illness, these changes resolved by 3-4 months.”

This study, “Longitudinal Assessment of Cardiac Outcomes of Multisystem Inflammatory Syndrome in Children Associated with COVID-19 Infections,” was published in the Journal of the American Heart Association.