While 80%-85% of children with multisystem inflammatory syndrome have cardiovascular involvement, “lack of knowledge about the short-term consequences of MIS-C has led to uncertainty among physicians in making recommendations about follow-up,” Daisuke Matsubara, MD, PhD, and colleagues wrote in their paper, which was published in the Journal of the American Heart Association.
Dr. Matsubara, of the department of pediatrics at the Children’s Hospital of Philadelphia, and colleagues examined cardiac outcomes among 60 patients aged 18 years or under admitted to two Philadelphia hospitals with MIS-C between April 2020 and January 2021. They compared those with outcomes in 60 age-matched healthy children who had undergone echocardiography for a range of non–COVID-related conditions such as chest pain or syncope.
The study used echocardiography, MRI, biochemistry, and functional and clinical parameters to assess the degree of change and damage to the heart at 3 months after admission.
When the patients first presented to a hospital, 42 had biochemical signs of myocardial injury, such as elevated brain-type natriuretic peptide and troponin levels. However, most patients’ symptoms were no longer present by the time they were discharged from hospital.
The researchers found that 81% of patients who presented with myocardial injury had lost the left atrial contraction phase. This dropped to 51% during the subacute phase, then 30% at 1 month. By 3-4 months, all patients achieved normal left atrial contraction phase.
At 1 month after admission, all MIS-C patients had significant signs of cardiac strain, compared with controls, including changes to global longitudinal strain, global circumferential strain, circumferential early diastolic strain rate, and right ventricular free wall longitudinal strain.
Parameters of strain normalized by 3 months
All parameters of strain had normalized, compared with controls, by 3 months. In the case of global longitudinal strain and left atrial strain, the median time to normalization was 6 days. For left ventricular ejection fraction the median time to normalization was 8 days and for right ventricular free wall longitudinal strain it was 9 days.
A small difference persisted with global longitudinal strain, but the authors said the difference was within the range of normal published values and not clinically relevant. The dysfunction appeared to be spread evenly across the heart rather than varying between segments, they noted.
“Deformation analysis could detect subtle myocardial changes; therefore, our study suggests the absence of persistent subclinical myocardial dysfunction after 3-4 months,” Dr. Matsubara said in an interview.
Four patients experienced small coronary aneurysms during the acute phase of MIS-C, but all had resolved within 2 months and none experienced any further lesions.
Among the 14 patients who underwent cardiac MRI at presentation, 2 had evidence of myocardial edema and fibrosis during the subacute phase of illness, despite having normal left ventricular systolic function and conventional echocardiography.
At follow-up, only one patient had residual edema; this individual had no evidence of fibrosis and had normal systolic function.