Ventricular function and tissue characterization by cardiac magnetic resonance imaging following hospitalization for multisystem inflammatory syndrome in children: a prospective study

Long-Term Effects of COVID-19 on the Cardiopulmonary System in Adults and Children: Current Status and Questions to be Resolved by the National Institutes of Health Researching COVID to Enhance Recovery Initiative

TOPIC IMPORTANCE

Long COVID may occur in at least 10% of patients recovering from SARS-CoV-2 infection and often is associated with debilitating symptoms. Among the organ systems that might be involved in its pathogenesis, the respiratory and cardiovascular systems may be central to common symptoms seen in survivors of COVID-19, including fatigue, dyspnea, chest pain, cough, and exercise intolerance. Understand the exact symptomatology, causes, and effects of long COVID on the heart and lungs may help us to discover new therapies. To that end, the National Institutes of Health is sponsoring a national study population of diverse volunteers to support large-scale studies on the long-term effects of COVID-19.

REVIEW FINDINGS

The National Institutes of Health Researching COVID to Enhance Recovery (RECOVER) initiative currently is recruiting participants in the United States to answer critical questions about long COVID. The study comprises adult and pediatric cohorts as well as an electronic health record cohort. Based on symptoms, individuals undergo prespecified medical testing to understand whether abnormalities can be detected and are followed up longitudinally. Herein, we outline current understanding of the clinical symptoms and pathophysiologic features of long COVID with respect to the cardiopulmonary system in adults and children and then determine how the clinical, electronic health record, and autopsy cohorts of the RECOVER initiative will attempt to answer the most pressing questions surrounding the long-term effects of COVID-19.

SUMMARY

Data generated from the RECOVER initiative will provide guidance about missing gaps in our knowledge about long COVID and how they might be filled by data gathered through the RECOVER initiative.

Multisystem inflammatory syndrome in children associated with COVID-19: from pathophysiology to clinical management and outcomes

Multisystem inflammatory syndrome in children (MIS-C), also known as pediatric inflammatory multisystem syndrome (PIMS), is a new postinfectious illness associated with COVID-19, affecting children after SARS-CoV-2 exposure. The hallmarks of this disorder are hyperinflammation and multisystem involvement, with gastrointestinal, cardiac, mucocutaneous, and hematologic disturbances seen most commonly. Cardiovascular involvement includes cardiogenic shock, ventricular dysfunction, coronary artery abnormalities, and myocarditis. Now entering the fourth year of the pandemic, clinicians have gained some familiarity with the clinical presentation, initial diagnosis, cardiac evaluation, and treatment of MIS-C. This has led to an updated definition from the Centers for Disease Control and Prevention in the USA driven by increased experience and clinical expertise. Furthermore, the available evidence established expert consensus treatment recommendations supporting a combination of immunoglobulin and steroids. However, the pathophysiology of the disorder and answers to what causes this remain under investigation. Fortunately, long-term outcomes continue to look promising, although continued follow-up is still needed. Recently, COVID-19 mRNA vaccination is reported to be associated with reduced risk of MIS-C, while further studies are warranted to understand the impact of COVID-19 vaccines on MIS-C. We review the findings and current literature on MIS-C, including pathophysiology, clinical features, evaluation, management, and medium- to long-term follow-up outcomes.

Cardiovascular Follow-up of Patients Treated for MIS-C

OBJECTIVES

To assess the prevalence of residual cardiovascular pathology by cardiac MRI (CMR), ambulatory rhythm monitoring, and cardiopulmonary exercise testing (CPET) in patients ∼6 months after multisystem inflammatory disease in children (MIS-C).

METHODS

Patients seen for MIS-C follow-up were referred for CMR, ambulatory rhythm monitoring, and CPET ∼6 months after illness. Patients were included if they had ≥1 follow-up study performed by the time of data collection. MIS-C was diagnosed on the basis of the Centers for Disease Control and Prevention criteria. Myocardial injury during acute illness was defined as serum Troponin-I level >0.05 ng/mL or diminished left ventricular systolic function on echocardiogram.

RESULTS

Sixty-nine of 153 patients seen for MIS-C follow-up had ≥1 follow-up cardiac study between October 2020-June 2022. Thirty-seven (54%) had evidence of myocardial injury during acute illness. Of these, 12 of 26 (46%) had ≥1 abnormality on CMR, 4 of 33 (12%) had abnormal ambulatory rhythm monitor results, and 18 of 22 (82%) had reduced functional capacity on CPET. Of the 37 patients without apparent myocardial injury, 11 of 21 (52%) had ≥1 abnormality on CMR, 1 of 24 (4%) had an abnormal ambulatory rhythm monitor result, and 11 of 15 (73%) had reduced functional capacity on CPET. The prevalence of abnormal findings was not statistically significantly different between groups.

CONCLUSIONS

The high prevalence of abnormal findings on follow-up cardiac studies and lack of significant difference between patients with and without apparent myocardial injury during hospitalization suggests that all patients treated for MIS-C warrant cardiology follow-up.

Cardiac manifestations of MIS-C: cardiac magnetic resonance and speckle-tracking data

Background

Cardiac involvement is central in MIS-C and represents the main cause of morbidity. In this study, we aimed to assess myocardial damage in patients with MIS-C using cardiac magnetic resonance (CMR) during the acute phase, as well as left ventricular and atrial longitudinal strain on admission, at discharge, and after 3 months.

Methods

We performed a single-center prospective cohort study and case-control study. Between September 2020 and February 2022, we enrolled 39 patients hospitalized for MIS-C at our center. We performed left ventricular and atrial longitudinal 2D strain analysis on admission and during follow-up; echocardiographic data were compared to a matched control population. Patients above 4 years old with increased troponin underwent CMR.

Results

Of 24 patients (mean age: 8.2 ± 4.9 years) who underwent CMR, 14 (58%) presented myocardial edema and 6 (25%) late gadolinium enhancement (LGE). LGE was associated with older age (p < 0.01), increased BMI (p = 0.03), increased ferritin levels (p < 0.001), lower left ventricular (LV) ejection fraction (p < 0.001), LV longitudinal strain (p = 0.004), left atrial (LA) strain (p = 0.05), and prolonged hospital stay (p = 0.02). On admission, LV ejection fraction, LV longitudinal strain, and LA strain were impaired, but each improved gradually over time; LVEF was the fastest to recover, while global LV longitudinal strain was still impaired as compared to controls after 3 months (p = 0.01).

Conclusion

Our study demonstrates that myocardial injury is present in a quarter of MIS-C patients, and impaired LA and LV myocardial deformation persist for at least several weeks after the acute phase. CMR and LV/LA strain could help us to individualize follow-up of MIS-C patients.

Evaluation of late cardiac effects after multisystem inflammatory syndrome in children

Introduction

Multisystem inflammatory syndrome in children (MIS-C) is associated with important cardiovascular morbidity during the acute phase. Follow-up shows a swift recovery of cardiac abnormalities in most patients. However, a small portion of patients has persistent cardiac sequelae at mid-term. The goal of our study was to assess late cardiac outcomes of MIS-C.

Methods

A prospective observational multicenter study was performed in children admitted with MIS-C and cardiac involvement between April 2020 and March 2022. A follow-up by NT-proBNP measurement, echocardiography, 24-h Holter monitoring, and cardiac MRI (CMR) was performed at least 6 months after MIS-C diagnosis.

Results

We included 36 children with a median age of 10 (8.0-11.0) years, and among them, 21 (58%) were girls. At diagnosis, all patients had an elevated NT-proBNP, and 39% had a decreased left ventricular ejection fraction (LVEF) (<55%). ECG abnormalities were present in 13 (36%) patients, but none presented with arrhythmia. Almost two-thirds of patients (58%) had echocardiographic abnormalities such as coronary artery dilation (20%), pericardial effusion (17%), and mitral valve insufficiency (14%). A decreased echocardiographic systolic left ventricular (LV) function was detected in 14 (39%) patients. A follow-up visit was done at a mean time of 12.1 (±5.8) months (range 6-28 months). The ECG normalized in all except one, and no arrhythmias were detected on 24-h Holter monitoring. None had persistent coronary artery dilation or pericardial effusion. The NT-proBNP level and echocardiographic systolic LV function normalized in all patients, except for one, who had a severely reduced EF. The LV global longitudinal strain (GLS), as a marker of subclinical myocardial dysfunction, decreased (z < -2) in 35%. CMR identified one patient with severely reduced EF and extensive myocardial fibrosis requiring heart transplantation. None of the other patients had signs of myocardial scarring on CMR.

Conclusion

Late cardiac outcomes after MIS-C, if treated according to the current guidelines, are excellent. CMR does not show any myocardial scarring in children with normal systolic LV function. However, a subgroup had a decreased GLS at follow-up, possibly as a reflection of persistent subclinical myocardial dysfunction.

SARS-CoV-2 infection and recovery in children: Distinct T cell responses in MIS-C compared to COVID-19

SARS-CoV-2 infection for most children results in mild or minimal symptoms, though in rare cases severe disease can develop, including a multisystem inflammatory syndrome (MIS-C) with myocarditis. Here, we present longitudinal profiling of immune responses during acute disease and following recovery in children who developed MIS-C, relative to children who experienced more typical symptoms of COVID-19. T cells in acute MIS-C exhibited transient signatures of activation, inflammation, and tissue residency which correlated with cardiac disease severity, while T cells in acute COVID-19 upregulated markers of follicular helper T cells for promoting antibody production. The resultant memory immune response in recovery showed increased frequencies of virus-specific memory T cells with pro-inflammatory functions in children with prior MIS-C compared to COVID-19 while both cohorts generated comparable antibody responses. Together our results reveal distinct effector and memory T cell responses in pediatric SARS-CoV-2 infection delineated by clinical syndrome, and a potential role for tissue-derived T cells in the immune pathology of systemic disease.