Early Cardiac Outcomes Good in Children With MIS-C After COVID-19

Cardiac issues related to the multisystem inflammatory syndrome in children (MIS-C) that can develop after recovery from COVID-19 resolve relatively quickly, a longitudinal study indicates.

Although echocardiographic impairments were observed in patients with MIS-C, most resolved completely within 3 to 4 months, researchers led by Daisuke Matsubara, MD, PhD (Children’s Hospital of Philadelphia, PA), report. Moreover, myocardial injury was prevalent at presentation, but it was not associated with short-term echocardiographic outcomes and most patients had normal biomarker levels before discharge.

A small number of children also underwent cardiac magnetic resonance (CMR) imaging, which showed only one case of residual edema—and no fibrosis—at follow-up, according to results published online January 19, 2022, in the Journal of the American Heart Association.

“Our short-term study suggests that functional recovery and coronary outcomes are good in multisystem inflammatory syndrome in children,” Matsubara et al write. “Use of sensitive deformation parameters [on echocardiography] provides further reassurance that there is no persistent subclinical dysfunction after 3 months.”

The findings have implications for the management of these patients after they leave the hospital, particularly as it pertains to participation in physical activity, the investigators say.

“Our study suggests that patients who suffered MIS-C could return to normal physical activity and sports participation after clearance by echocardiography and an electrocardiogram after 3 to 4 months,” Matsubara told TCTMD in an email.

Short Recovery of Cardiac Function

Prior studies of MIS-C have shown it is associated with cardiovascular involvement—which can include shock, LV dysfunction, coronary artery abnormalities, and myocardial injury—in 80% to 85% of cases. But there is limited evidence around the longitudinal trajectory of cardiac outcomes in these children.

In this study, Matsubara et al tracked cardiac measures for 3 to 4 months using CMR and conventional transthoracic echocardiography along with speckle-tracking analysis to assess myocardial deformation parameters. The analysis included 60 patients with MIS-C (mean age 10.0 years; 60% male) who were admitted to the Children’s Hospital of Philadelphia or an affiliate, St. Peter’s University Hospital, between April 2020 and January 2021 as well as 60 healthy controls (mean age 11.5 years; 55% male) who received echocardiograms to evaluate benign heart murmurs, chest pain, syncope, or a family history of cardiac disease.

The patients with MIS-C spent a median of 6 days in the hospital, with 70% requiring intensive care and 22% invasive ventilation. Most were treated with IV immunoglobulin (90%) and systemic steroids (92%).

On echo, most deformation parameters including LV global longitudinal strain, peak left atrial strain, and RV free wall strain, improved rapidly within the first week, with complete normalization seen by 3 months. The longitudinal early diastolic strain rate didn’t improve as quickly, but also normalized by 3 months.

Compared with the healthy controls, patients with MIS-C had impairments in all strain parameters at 1 month. By 3 months, only global longitudinal strain remained lower, although it was in normal range.

“This rapid functional recovery of LV diastolic function is a distinctive feature of MIS-C. Many other causes of acute heart failure in children result in more-delayed recovery of diastolic function over several months or years,” the researchers write. That difference, they say, “has important implications for resumption of vigorous and competitive physical activities and provides direct evidence to support current ‘consensus-based’ recommendations.”

Most patients (70%) had evidence of myocardial injury defined using elevations in troponin I or brain-type natriuretic peptide, with levels returning to normal during the subacute stage before discharge.

Matsubara pointed out that some of the findings differ from what is seen in adults with COVID-19, who tend to have evidence of myocardial impairment on echo and CMR over a longer period of time. In addition, high troponin levels are related to prognosis in adults. “Our study could explain the different mechanisms of myocardial injury between MIS-C and COVID-19 myocarditis,” he said.

Among other findings, on ECG, 10 patients had inverted T waves in lateral/inferior leads—all normalized within 3 months. Just four patients (7%) had small coronary aneurysms at presentation, and all resolved within 2 months. At the last clinical visit, all patients were in NYHA class I without fatigue, cardiac complaints, or other symptoms. There were no deaths or unexpected cardiac events during follow-up.

Reassuring Findings

Commenting for TCTMD, Kevin Friedman, MD (Boston Children’s Hospital, MA), a member of the American Heart Association’s Council on Lifelong Congenital Heart Disease and Heart Health in the Young (Young Hearts), said the study adds to what is already known from prior studies and clinical experience: “Although some children with MIS-C get very sick and their hearts are involved acutely, they get better.”

By looking at more-subtle measures of cardiac function—which normalized over just a few months—that indicates, Friedman said, that “there probably aren’t going to be long-term cardiac issues in the majority of these patients, even ones who are quite sick.”

Although “we’ll still maintain a level of surveillance and concern,” he added, cardiology follow-up visits probably won’t be needed over the long term. He acknowledged that any potential link between MIS-C and cardiac problems in adulthood remains unknown, but doesn’t think these patients will be at increased long-term risk.

“I think it’s very reassuring that we are not seeing lasting cardiac abnormalities, even in the children who are quite severely affected in the acute phase,” Friedman said. “Families and parents and providers should be reassured that even the sickest of kids are generally not having long-term or even medium-term cardiac involvement and even more subtle markers of ventricular function of the heart normalize in basically everyone.”

Matsubara said that even though the study showed a good cardiac outcomes among patients with MIS-C, a larger multicenter study is needed considering the small number of cases examined. “In addition,” he said, “we need longer-term follow-up studies.”