Heart issues resolved quickly in MIS-C

According to a longitudinal analysis, heart problems due to multisystem inflammatory syndrome in children (MIS-C) related to COVID-19 infection are usually resolved within 3 months.

Among 42 children with MIS-C who showed evidence of myocardial damage, 81% lost the left atrial contraction phase during acute illness, dropping to 52% in the days immediately following vasoactive treatment, Anirban reported. Banerjee, MD, of Children’s Hospital of Philadelphia and colleagues.

The left atrial contraction phase normalized in all patients 3 to 4 months later, the researchers noted in the Journal of the American Heart Association.

Six patients had elevated levels of brain-like natriuretic peptides, 13 had elevated levels of troponin, and 23 had elevated levels of both. There were no deaths or unexpected cardiac events.

The results of the study support guidelines which indicate that children with MIS-C can gradually resume physical activities such as competitive sports over the course of 3 months, the authors noted.

In agreement with previous studies, all strain parameters, including global longitudinal left ventricular (LV) strain, peak left atrial strain, longitudinal early diastolic strain rate, and right ventricular free wall strain, recovered during the first week, followed by complete normalization at 3 months.

The median time to normalization for global longitudinal deformity and left atrial deformity was 6 days. The median time to normalization for LV ejection fraction was 8 days and 9 days for right ventricular free wall deformity.

“This rapid functional recovery of LV diastolic function is a distinctive feature of MIS-C,” Banerjee and colleagues wrote. “Many other causes of acute heart failure in children result in delayed recovery of diastolic function over months or years.”

For example, in Kawasaki disease, which presents very similarly to MIS-C, diastolic dysfunction may persist up to one year. In other cases of non-COVID viral myocarditis, diastolic dysfunction may persist for more than a year.

MIS-C can develop within weeks of COVID-19 infection and is more common in children 6 to 10 years old. Children can present with heart, brain, skin and eyes problems. Adolescents who received the Pfizer/BioNTech vaccine were protected against severe MIS-C, a recent CDC study found.

Banerjee and colleagues analyzed data from 60 MIS-C patients and 60 age-matched controls. Patients with MIS-C were admitted to either Children’s Hospital of Philadelphia or St. Peter’s University Hospital of New Brunswick, New Jersey, from April 2020 to January 2021. All had positive tests of PCR or COVID antigen.

The average age of MIS-C patients was 10 years old, 60% were boys and 48% were black. The median length of hospitalization was 6 days. Patients were treated with intravenous immunoglobulins (90%) and/or systemic steroids (92%).

Patients with a history of cardiac dysfunction, congenital heart disease, exposure to cardiotoxic agents, and chronic lung disease, as well as those treated with extracorporeal membrane oxygenation, were excluded.

Two-dimensional echocardiography, speckle follow-up echocardiography, clinical and cardiovascular MRI data were obtained from patients with MIS-C. Two-dimensional echocardiography data were taken at four time points: during the acute phase of the disease, during the subacute phase in the days immediately following treatment, at 1 month, and at 3 or 4 months. Only 25 patients successfully followed at 3 or 4 months.

Banerjee and his team acknowledged the low follow-up rate in the study, noting that this may be the result of the lack of standardization around follow-up care for MIS-C, since it is a “newly described”. They also pointed out that their study only considered short-term results at 3 or 4 months and did not measure potential longer-term impacts.