Cardiovascular Magnetic Resonance in Children with Multisystem Inflammatory Syndrome in Children (MIS-C) Associated with COVID-19: Institutional Protocol-Based Medium-Term Follow-up Study

Abstract

Multisystem inflammatory syndrome in children (MIS-C) secondary to COVID-19 infection in previously healthy children often results in subtle but persistent echocardiographic abnormalities despite complete clinical recovery. This study was done to investigate medium-term cardiovascular outcomes of patients with MIS-C using cardiovascular magnetic resonance imaging (CMR). This is a single-center retrospective study of patients aged less than 21 years, diagnosed with MIS-C who received an outpatient CMR, around 6 months after discharge. CMR was done in patients with significant troponin leak or depressed LVEF. CMR performed on a GE Signa HDxt 1.5 Tesla magnet with a myocarditis protocol. Diagnosis of myocarditis was determined by the original Lake Louise Criteria. There were 21 patients with a median age of 11 years, (IQR 8–13 years), who underwent CMR at median follow-up duration of 6 months (IQR 5–7 months). At the peak of illness during admission, there were 95.2% patients with abnormal Troponin I and BNP. By echocardiogram, 76.2% had left ventricular systolic dysfunction and 9.5% had coronary ectasia, which all resolved by 6 months. By CMR, there were five patients (23.8%) with abnormal left atrial volume, one patient (4.8%) with an abnormal indexed left ventricular end-diastolic volume, and three patients (15%) with abnormal LVEF. There was no evidence of myocardial edema in T2-weighted image sequence. There were three patients with persistent late gadolinium enhancement (14.3%). Follow-up CMR is a useful tool in diagnosing subtle myocardial abnormalities and guide necessity for future follow-up.

Long-term Cardiovascular Outcomes of Multisystem Inflammatory Syndrome in Children Associated with COVID-19 using an Institution Based Algorithm

“…With evidence of persistent diastolic dysfunction in a subgroup of patients up to 6-months, and suspicion of ongoing subclinical damage or previous scarring, CMR is an additional armament to help distinguish between these two processes and potentially provides novel insights into prognosis and pathophysiology. Since our last publication on mid-term CMR results from the same cohort, CMR was available in 3 more patients (25) (24,44,45). Myocardial edema on T2 weighted image was reported by Barris et.al in 44%, the reason for this large number of patients having persistent abnormal T2 weighted signal ratio, long after initial insult is unclear (44).…”

“…Limited, single center studies have described almost complete resolution of ventricular systolic dysfunction and coronary artery changes within 3-6 months following discharge (15,(19)(20)(21). However, there is some evidence that subtle abnormalities in diastolic function on TTE and evidence of myocardial injury on cardiovascular magnetic resonance imaging (CMR) may persist longer (19)(20)(21)(22)(23)(24)(25). We have previously described the CMR results in a subset of patients at 6-month follow-up who had initial presentation with signi cant troponin leak and/or left ventricular systolic dysfunction (25).…”

“…However, there is some evidence that subtle abnormalities in diastolic function on TTE and evidence of myocardial injury on cardiovascular magnetic resonance imaging (CMR) may persist longer (19)(20)(21)(22)(23)(24)(25). We have previously described the CMR results in a subset of patients at 6-month follow-up who had initial presentation with signi cant troponin leak and/or left ventricular systolic dysfunction (25). However, each of these studies is limited by the number of patients enrolled, the duration and compliance with follow-up and the considerable heterogeneity in testing.…”

Parametric Mapping Cardiac Magnetic Resonance Imaging for the Diagnosis of Myocarditis in Children in the Era of COVID-19 and MIS-C

“…from the hospital showed no evidence of edema in T2-weighed sequences, and three patients had LGE [84]. Figure 9 describes CMR findings of elevated T1 relaxation time but no LGE in an 8-year-old girl three months after MIS-C.…”

“…Other studies have shown diffuse myocardial edema on T2 inversion recovery sequences and native T1 mapping with no evidence of LGE one week after onset of symptoms, suggesting that CMR parametric mapping helps diagnose acute myocarditis in MIS-C in children [ 83 ]. On the other hand, another study in children where CMR was performed on 21 MIS-C patients six months after discharge from the hospital showed no evidence of edema in T2-weighed sequences, and three patients had LGE [ 84 ]. Figure 9 describes CMR findings of elevated T1 relaxation time but no LGE in an 8-year-old girl three months after MIS-C.…”