Children With Acute Myocarditis Often Have Persistent Subclinical Changes as Revealed by Cardiac Magnetic Resonance

Post-acute midterm follow-up cardiac MRI findings and clinical outcomes in patients with COVID-19 vaccine-associated myocarditis: a comprehensive systematic review and meta-analysis

PURPOSE

Although previous investigations revealed favourable in-hospital outcomes of COVID-19 vaccine-related myocarditis, the mid-term prognosis is still unclear. Hence, we aim to summarise existing evidence on the follow-up imaging and clinical findings in patients with COVID-19 vaccine-related myocarditis.

METHODS

We performed a systematic search in online databases using relevant key terms covering COVID-19 vaccine, myocarditis, follow-up, and cardiac MRI. We included all observational studies that reported cardiac MRI findings of patients with myocarditis following COVID-19 vaccination in both acute and follow-up phases. Data on clinical outcomes and cardiac MRI findings were extracted and pooled using a random-effect model.

RESULTS

A total of 27 studies (126 patients) met our eligibility criteria. At the time of follow-up, myocarditis symptoms were resolved in all patients, but abnormal electrocardiography and elevated troponin levels were detected in 18.7% and 3.8% of them, respectively. Median imaging follow-up times varied from 3 to 6.3 months. On follow-up cardiac MRI, the persistence of LGE was observed in 76% (95%CI: 62 to 85%), but its extension declined compared to the baseline in almost all patients. Persistent LGE was accompanied by myocardial edoema in six patients, and it was consistent with myocardial fibrosis (LGE without edoema) in the remaining cases. Mean changes (95%CI) of cardiac MRI left ventricular ejection fraction (LVEF) (%) was +2.97 (+1.59 to +4.34) from baseline.

CONCLUSION

In conclusion, although most patients likely experience favourable clinical outcomes without serious complications, cardiac MRI abnormalities, mainly LGE, may persist in a notable proportion of them beyond the acute phase.

Cardiovascular magnetic resonance (CMR) and positron emission tomography (PET) imaging in the diagnosis and follow-up of patients with acute myocarditis and chronic inflammatory cardiomyopathy : A review paper with practical recommendations on behalf of the European Society of Cardiovascular Radiology (ESCR)

Advanced cardiac imaging techniques such as cardiovascular magnetic resonance (CMR) and positron emission tomography (PET) are widely used in clinical practice in patients with acute myocarditis and chronic inflammatory cardiomyopathies (I-CMP). We aimed to provide a review article with practical recommendations from the European Society of Cardiovascular Radiology (ESCR), in order to guide physicians in the use and interpretation of CMR and PET in clinical practice both for acute myocarditis and follow-up in chronic forms of I-CMP.

Isolated myocardial edema in cardiac magnetic resonance - in search of a management strategy

Isolated myocardial edema not accompanied by late gadolinium enhancement (LGE) may be occasionally found on cardiac magnetic resonance (CMR). This type of picture may be encountered in patients with suspected myocarditis, post some acute cardiac events, with cardiac allograft rejection or even in athletes after an extreme exercise. Currently, there is no clear management strategy for this type of incidental finding. In this narrative review we discuss the methods and pitfalls of edema detection with means of CMR, review published data on isolated myocardial edema for each of the most probable clinical scenarios and propose a structured clinical decision-making algorithm to help clinicians navigate through this type of CMR result. Finally, we highlight the most important gaps in evidence related to isolated myocardial edema without fibrosis, where further research is particularly needed.

Cardiac Magnetic Resonance Findings of Coronavirus Disease 2019 (COVID-19) Vaccine-Associated Myopericarditis at Intermediate Follow-Up: A Comparison with Classic Myocarditis

OBJECTIVE

To report intermediate cardiac magnetic resonance (CMR) findings of coronavirus disease 2019 (COVID-19) vaccine-associated myopericarditis (C-VAM) and compare with classic myocarditis.

STUDY DESIGN

Retrospective cohort study including children diagnosed with C-VAM from May 2021 through December 2021 with early and intermediate CMR. Patients with classic myocarditis from January 2015 through December 2021 and intermediate CMR were included for comparison.

RESULTS

There were 8 patients with C-VAM and 20 with classic myocarditis. Among those with C-VAM, CMR performed at a median 3 days (IQR 3, 7) revealed 2 of 8 patients with left ventricular ejection fraction <55%, 7 of 7 patients receiving contrast with late gadolinium enhancement (LGE), and 5 of 8 patients with elevated native T1 values. Borderline T2 values suggestive of myocardial edema were present in 6 of 8 patients. Follow-up CMRs performed at a median 107 days (IQR 97, 177) showed normal ventricular systolic function, T1, and T2 values; 3 of 7 patients had LGE. At intermediate follow-up, patients with C-VAM had fewer myocardial segments with LGE than patients with classic myocarditis (4/119 vs 42/340, P = .004). Patients with C-VAM also had a lower frequency of LGE (42.9 vs 75.0%) and lower percentage of left ventricular ejection fraction <55% compared with classic myocarditis (0.0 vs 30.0%), although these differences were not statistically significant. Five patients with classic myocarditis did not receive an early CMR, leading to some selection bias in study design.

CONCLUSIONS

Patients with C-VAM had no evidence of active inflammation or ventricular dysfunction on intermediate CMR, although a minority had persistent LGE. Intermediate findings in C-VAM revealed less LGE burden compared with classic myocarditis.

Relapsing myocarditis following initial recovery of post COVID-19 vaccination in two adolescent males - Case reports

Whilst there has been significant public health benefits associated with global use of COVID-19 spike protein vaccines, potential serious adverse events following immunization have been reported. Acute myocarditis is a rare complication of COVID19 vaccines and often it is self-limiting. We describe two cases experiencing recurrent myocarditis following mRNA COVID-19 vaccine despite a prior episode with full clinical recovery. Between September 2021-September 2022 we observed two male adolescents with recurrent myocarditis related to mRNA-based-COVID19 vaccine. During the first episode both patients presented with fever and chest pain few days after their second dose of BNT162b2 mRNA Covid-19 Vaccine (Comirnaty®). The blood exams showed increased cardiac enzymes. In addition, complete viral panel was run, showing HHV7 positivity in a single case. The left ventricular ejection fraction (LVEF) was normal at echocardiogram but cardiac magnetic resonance scanning (CMR) was consistent with myocarditis. They were treated with supportive treatment with full recovery. The 6 months follow-up demonstrated good clinical conditions with normal cardiological findings. The CMR showed persistent lesions in left ventricle 's wall with LGE. After some months the patients presented at emergency department with fever and chest pain and increased cardiac enzymes. No decreased LVEF was observed. The CMR showed new focal areas of edema in the first case report and stable lesions in the second one. They reached full recovery with normalization of cardiac enzymes after few days. These case reports outline the need of strict follow-up in patients with CMR consistent with myocarditis after mRNA-based-COVID19 vaccine. More efforts are necessary to depict the underlying mechanisms of myocarditis after SARS-CoV2 vaccination to understand the risk of relapsing and the long-term sequelae.

Quantitative cardiac MRI parameters for assessment of myocarditis in children and adolescents: a systematic review and meta-analysis

AIM

To evaluate the role of quantitative cardiac magnetic resonance imaging (CMRI) parameters in myocarditis, including acute and chronic myocarditis (AM and CM), for children and adolescents.

MATERIALS AND METHODS

PRISMA principles were followed. PubMed, EMBASE, Web of Science, Cochrane Library, and grey literature were searched. The Newcastle-Ottawa Scale (NOS) and the Agency for Healthcare Research and Quality (AHRQ) checklist were utilised for quality assessment. Quantitative CMRI parameters were extracted and a meta-analysis was performed in comparison with healthy controls. The overall effect size was measured as the weighted mean difference (WMD).

RESULTS

Ten quantitative CMRI parameters of seven studies were analysed. Compared with the control group, the myocarditis group reported longer native T1 relaxation time (WMD=54.00, 95% confidence interval [CI]: 33.21,74.79, p<0.001), longer T2 relaxation time (WMD=2.13, 95% CI: 0.98, 3.28, p<0.001), increased extracellular volume (ECV; WMD=3.13, 95% CI: 1.34,4.91, p=0.001), elevated early gadolinium enhancement (EGE) ratio (WMD=1.47, 95% CI: 0.65,2.28, p<0.001), and increased T2-weighted ratio (WMD=0.43, 95% CI: 0.21,0.64, p<0.001). The AM group had longer native T1 relaxation times (WMD=72.02, 95% CI: 32.78,111.27, p<0.001), increased T2-weighted ratios (WMD=0.52, 95% CI: 0.21,0.84 p=0.001), and impaired left ventricular ejection fractions (LVEF; WMD=-5.84, 95% CI: -9.69, -1.99, p=0.003). Impaired LVEF (WMD=-2.24, 95% CI: -3.32, -1.17, p<0.001) was observed in the CM group.

CONCLUSION

Statistical differences can be observed in some CMRI parameters between patients with myocarditis and healthy controls; however, apart from native T1 mapping, there were no large differences in other parameters between two groups, which may reveal the limited benefit of CMRI in assessing myocarditis in children and adolescents.

Pediatric Myocarditis

Myocarditis is a condition caused by acute or chronic inflammation of the cardiac myocytes, resulting in associated myocardial edema and myocardial injury or necrosis. The exact incidence is unknown, but is likely underestimated, with more mild cases going unreported. Diagnosis and appropriate management are paramount in pediatric myocarditis, as it remains a recognized cause of sudden cardiac death in children and athletes. Myocarditis in children is most often caused by a viral or infectious etiology. In addition, there are now two highly recognized etiologies related to Coronavirus disease of 2019 (COVID-19) infection and the COVID-19 mRNA vaccine. The clinic presentation of children with myocarditis can range from asymptomatic to critically ill. Related to severe acute respiratory syndrome-Coronavirus 2 (SARs-CoV-2), children are at greater risk of developing myocarditis secondary to COVID-19 compared to the mRNA COVID-19 vaccine. Diagnosis of myocarditis typically includes laboratory testing, electrocardiography (ECG), chest X-ray, and additional non-invasive imaging studies with echocardiogram typically being the first-line imaging modality. While the reference standard for diagnosing myocarditis was previously endomyocardial biopsy, with the new revised Lake Louise Criteria, cardiac magnetic resonance (CMR) has emerged as an integral non-invasive imaging tool to assist in the diagnosis. CMR remains critical, as it allows for assessment of ventricular function and tissue characterization, with newer techniques, such as myocardial strain, to help guide management both acutely and long term.

Cardiac MRI in midterm follow-up of MISC: a multicenter study

In this multicenter retrospective study we aimed to evaluate the outcome of cardiac involvement in children affected by multisystem inflammatory syndrome (MIS-C), assessed through cardiac magnetic resonance (CMR). Children referring to three Italian tertiary pediatric centers between February 2020 and November 2021 with a diagnosis of MIS-C, who underwent CMR during a follow-up visit, were enrolled. Demographic, clinical, laboratory, treatment, and outcome data were collected. Twenty MIS-C patients (aged 9-17, median 12 years) were included in the study. Heart involvement at onset was testified by hypotension/shock (55%), laboratory evidence of myocardial involvement (100%), reduced LV ejection fraction (EF) on echocardiography (83%), and/or need for inotrope agents (40%); they all presented good clinical, laboratory, and echocardiographic response to treatment. CMR was performed after a median interval of 3 months from discharge. Pericardial effusion and myocardial edema were found in 5% of patients. Mild residual left ventricular (LV) dysfunction was found in 20% of patients, all showing normal echocardiographic LVEF at discharge. Minimal myocardial scars were found in 25% by late gadolinium enhancement (LGE). One patient was evaluated at two consecutive time points, showing partial resolution of a myocardial scar after 7 months from its first finding.

CONCLUSION

Despite the severity of heart involvement in the acute MIS-C phase, the mid-term cardiac outcome is good. Direct cardiac tissue viral invasion may be involved in MIS-C pathogenesis.

WHAT IS KNOWN

• Heart involvement is common in MIS-C, but conflicting findings have been shown regarding cardiac outcome when assessed through cardiac MRI.

WHAT IS NEW

• Midterm cardiac MRI shows mild abnormalities in patients recovered from MIS-C with any grade of severity of cardiac involvement at presentation.

Cardiac Magnetic Resonance Findings after Multisystem Inflammatory Syndrome in Children

OBJECTIVE

To describe the cardiac magnetic resonance (MR) findings of children recovered from multisystem inflammatory syndrome in children (MIS-C) longer than 3 months after acute illness.

STUDY DESIGN

We performed a retrospective cohort study of children hospitalized with MIS-C at a single institution receiving cardiac MR imaging between July 2020 and May 2021. Patient demographics, echocardiogram data from diagnosis through follow-up, and cardiac MR data obtained at approximately 3 months after hospitalization were recorded.

RESULTS

In total, 51 children with a median age of 11.3 years were included; 80% of patients had left ventricular ejection fraction <55%, 65% of patients developed valvular regurgitation, and 20% of patients developed coronary artery dilation during acute illness. Cardiac MR was performed at a median time of 105 days after diagnosis; 8% of patients had left ventricular ejection fraction <55%; 1 patient had residual valvular regurgitation; and 2 patients had residual coronary artery dilation. Two of 51 patients were found to have late gadolinium enhancement, T1 mapping abnormalities, and abnormal or borderline extracellular volume calculations suggesting myocardial fibrosis. No patient had T2 mapping abnormalities corresponding with edema, and no patient met the modified Lake Louise criteria for acute myocarditis; 10 of 51 patients had isolated elevated T1 values.

CONCLUSIONS

At 3-5 months following diagnosis, cardiac MR reveals no evidence of acute myocarditis as described by the modified Lake Louise criteria in patients with MIS-C. Two patients were observed to have myocardial fibrosis without regional wall motion abnormalities, and 10 had isolated imaging changes (elevated T1 values) in the absence of macroscopic fibrosis.

Persistent Cardiac Magnetic Resonance Imaging Findings in a Cohort of Adolescents with Post-Coronavirus Disease 2019 mRNA Vaccine Myopericarditis

We describe the evolution of cardiac magnetic resonance imaging findings in 16 patients, aged 12-17 years, with myopericarditis after the second dose of the Pfizer mRNA coronavirus disease 2019 vaccine. Although all patients showed rapid clinical improvement, many had persistent cardiac magnetic resonance imaging findings at 3- to 8-month follow-up.

COVID-19-Vaccination-Induced Myocarditis in Teenagers: Case Series with Further Follow-Up

Presently, the whole globe is struggling the tough challenge of the COVID-19 pandemic. Vaccination remains the most effective and safe COVID-19 weapon for adults and in the paediatric population. Aside from possible mild and moderate post-vaccination side effects, more severe side effects may occur. We retrospectively analysed a group of 5 teenagers aged from 15 to 17 years with obesity/overweight (BMI ranging from 24.8 to 30) who presented typical myocarditis symptoms following the first or second dose (3 and 2 patients, respectively) of the COVID-19 vaccine. In the whole study group, a significant increase in troponin serum concentration was observed (1674–37,279.6 ng/L) with a further quick reduction within 3–4 days. In all patients, ST segments elevation or depression with repolarisation time abnormalities in electrocardiography were noticed. Chest X-ray results were within normal limits. Echocardiography showed normal left ventricular diameter (47–56.2 mm) with ejection fraction between 61–72%. All patients were diagnosed with myocarditis based on cardiac magnetic resonance (CMR) imaging. During further hospitalisation, swift clinical improvement was notable. Follow-up in the whole study group was obtained after 106–134 days from initial CMR, revealing no myocarditis symptoms, proper troponin level, and no ECG or echocardiographic abnormalities. At the same time, persistent myocardium injury features were detected in the whole study group, including ongoing myocarditis. COVID-19-vaccine-induced myocarditis seems to be a mild disease with fast clinical recovery, but the complete resolution of the inflammatory process may last over 3 months. Further follow-up and investigation for assessing subsequent implications and long-term COVID-19-vaccine-induced myocarditis is required.

Cardiac Magnetic Resonance Follow-Up of Children After Pediatric Inflammatory Multisystem Syndrome Temporally Associated With SARS-CoV-2 With Initial Cardiac Involvement

Background

Pediatric inflammatory multisystem syndrome temporally associated with SARS‐CoV‐2 (PIMS‐TS) is an inflammatory disease occurring in a small minority of children a few weeks after acute infection. Cardiac manifestations are common, but little is known about the potentially persistent heart changes after PIMS‐TS.

Purpose

To analyze the frequency and type of myocardial complications of PIMS‐TS with initial cardiac involvement assessed with cardiac magnetic resonance imaging (MRI), including parametric imaging, performed 3 months after hospitalization.

Study Type

Retrospective.

Population

Nineteen consecutive children (median age 10 years, interquartile range (IQR) 10–15 years, 74% male).

Field Strength/Sequence

Balanced steady state free precession (bSSFP, cine imaging), modified Look‐Locker (T1 mapping), T2‐prepared bSSFP (T2‐mapping), dark‐blood T2‐weighted turbo spin echo with fat suppression and phase sensitive inversion recovery (late gadolinium enhancement (LGE)) sequences at 1.5 T.

Assessment

Patients were scanned after a median of 99 days (IQR 89–104 days) from the diagnosis. MR data were reviewed by three independent observers, with 13, 2, and 5 years' experience in cardiac MRI. Pre‐ and post‐contrast T1, T2, extra‐cellular volume, and T2 signal intensity (T2 SI) ratio were calculated. Diagnosis of acute myocarditis was based on modified Lake Louise criteria. Cardiac MRI parameters were compared, where possible, to previously published pediatric normal values.

Statistical Tests

Interclass correlation coefficient and Bland–Altman repeatability analysis. A P‐value <0.05 was considered statistically significant.

Results

Despite cardiac involvement including decreased left ventricular ejection fraction (LVEF) (median LVEF = 47%, IQR 43%–53%) and increased troponin I (median 101 ng/mL, IQR 50–661 ng/mL) during hospitalization, there were no persistent cardiac changes observed in cardiac MR at follow‐up. All patients had normal size and function of the left ventricle and normal precontrast T1 and T2 relaxation times. There were no signs of LGE. Persistent, mild pericardial effusion (8–9 mm) was found in three (16%) patients.

Data Conclusion

There were no persistent changes on cardiac MRI in a group of children approximately 3 months post hospitalization due to PIMS‐TS with cardiac involvement. This supports the hypothesis that cardiac involvement during PIMS‐TS is a form of transient inflammatory response rather than direct and potentially persistent injury from the virus.

Level of Evidence

4

Technical Efficacy

Stage 3

Diagnosis and Management of Myocarditis in Children: A Scientific Statement From the American Heart Association

Myocarditis remains a clinical challenge in pediatrics. Originally, it was recognized at autopsy before the application of endomyocardial biopsy, which led to a histopathology-based diagnosis such as in the Dallas criteria. Given the invasive and low-sensitivity nature of endomyocardial biopsy, its diagnostic focus shifted to a reliance on clinical suspicion. With the advances of cardiac magnetic resonance, an examination of the whole heart in vivo has gained acceptance in the pursuit of a diagnosis of myocarditis. The presentation may vary from minimal symptoms to heart failure, life-threatening arrhythmias, or cardiogenic shock. Outcomes span full resolution to chronic heart failure and the need for heart transplantation with inadequate clues to predict the disease trajectory. The American Heart Association commissioned this writing group to explore the current knowledge and management within the field of pediatric myocarditis. This statement highlights advances in our understanding of the immunopathogenesis, new and shifting dominant pathogeneses, modern laboratory testing, and use of mechanical circulatory support, with a special emphasis on innovations in cardiac magnetic resonance imaging. Despite these strides forward, we struggle without a universally accepted definition of myocarditis, which impedes progress in disease-targeted therapy.

The Role of Cardiac Magnetic Resonance in Evaluation of Idiopathic Ventricular Arrhythmia in Children

The aim of the study was to assess the role of cardiovascular magnetic resonance (CMR) in the diagnosis of idiopathic VA in children. This retrospective single-centre study included a total of 80 patients with idiopathic ventricular arrhythmia that underwent routine CMR imaging between 2016 and 2020 at our institution. All patients underwent a 3.0 T scan involving balanced steady-state free precession cine images as well as dark-blood T2W images and assessment of late gadolinium enhancement (LGE). In 26% of patients (n = 21) CMR revealed cardiac abnormalities, in 20% (n = 16) not suspected on prior echocardiography. The main findings included: non-ischemic ventricular scars (n = 8), arrhythmogenic right ventricular cardiomyopathy (n = 6), left ventricular clefts (n = 4) and active myocarditis (n = 3). LGE was present in 57% of patients with abnormal findings. Univariate predictors of abnormal CMR result included abnormalities in echocardiography and severe VA (combination of >10% of 24 h VA burden and/or presence of ventricular tachycardia and/or polymorphic VA). CMR provides valuable clinical information in many cases of idiopathic ventricular arrhythmia in children, mainly due to its advanced tissue characterization capabilities and potential to assess the right ventricle.

An unusual cause of ventricular fibrillatory arrest

Myocarditis is an important cause of arrhythmogenic sudden cardiac arrest in the young. A strong index of suspicion is required as not only can arrhythmias be the only clinical manifestation but also because these patients can have normal cardiac biomarkers, electrocardiographic and echocardiographic findings, and inflammatory markers. Patients with ventricular arrhythmias in the setting of viral myocarditis, especially the ones in whom cardiac MRI findings normalise upon follow-up, tend to do well in the long run and an implantable cardioverter-defibrillator should be avoided in these patients; instead, a wearable defibrillator should be temporarily used as we did in this 7-year-old.

QRS fragmentation in children with suspected myocarditis: a possible additional diagnostic sign

AIMS

We aim to assess the diagnostic role of QRS fragmentation in children with suspected acute myocarditis.

BACKGROUND

Diagnosis of myocarditis in the paediatric population is challenging. Clinical suspicion, electrocardiogram, and laboratory tests are the main diagnostic features at presentation. However, electrocardiogram in patients with myocarditis is usually considered aspecific. We have previously described QRS fragmentation in adult patients with acute myocarditis.

METHODS

Patients aged less than 18 years, admitted between 2003 and 2019, and discharged with a diagnosis of acute myocarditis were included. Standard electrocardiogram, laboratory, and echocardiographic findings at admission and follow-up were reviewed. QRS fragmentation was defined by the presence of multiphasic R' spikes. Cardiac magnetic resonance and biopsy were performed in selected patients.

RESULTS

Twenty-one patients were analysed, 16 males (76%), median age 9.5 (2.5-16) years. At presentation, 12 patients (57%) displayed QRS fragmentation. Median ejection fraction was 40% (27-60). Nine patients (43%) underwent cardiac magnetic resonance and displayed late gadolinium enhancement. One patient underwent biopsy that showed borderline findings. Electrocardiogram leads showing QRS fragmentation correlated with distribution of late gadolinium enhancement. Median follow-up was 600 (190-2343) days. All patients were alive at last follow-up. Six patients (33%) patients displayed persistence of QRS fragmentation. Median ejection fraction was 60% (60-65%). In three patients (14%), ejection fraction remained depressed, two of which showed persistence of QRS fragmentation.

CONCLUSION

In this cohort of children with suspected myocarditis, QRS fragmentation was confirmed as a new additional diagnostic finding to look for at admission and during follow-up.