Cardiovascular manifestations and cardiac magnetic resonance follow-up of multisystem inflammatory syndrome in children (MIS-C).

OBJECTIVE: This study aimed to evaluate the cardiovascular manifestations and surveillance of multisystem inflammatory syndrome in children (MIS-C) and to determine the correlation of echocardiographic findings with cardiac magnetic resonance imaging findings. METHODS: Forty-four children diagnosed as MIS-C with cardiac involvement were enrolled in this observational descriptive study. The diagnosis of MIS-C was made according to the criteria of Centers for Disease Control and Prevention. Clinical findings, laboratory parameters, and electrocardiographic and echocardiographic findings at the time of diagnosis and during follow-up were evaluated. Cardiac magnetic resonance was performed on 28 (64%) cases. The 1-year follow-up imaging was performed in all cases with abnormal initial cardiac magnetic resonance findings. RESULTS: Forty-four patients (56.8% male) with a mean age of 8.5 ± 4.8 years were enrolled in this study. There was a significant positive correlation between high-sensitivity cardiac troponin T (mean: 162 ± 444.4 pg/ml) and N-terminal pro b-type natriuretic peptide (mean: 10,054 ± 11,604 pg/ml) (p < 0.01). Number of cases with an electrocardiographic and echocardiographic abnormality was 34 (77%) and 31 (70%), respectively. Twelve cases (45%) had left ventricular systolic dysfunction and 14 (32%) cases had pericardial effusion on admission. Three cases (11%) had cardiac magnetic resonance findings that may be attributed to the presence of myocardial inflammation, and pericardial effusion was present in seven (25%) cases. Follow-up cardiac magnetic resonances of all cases were normal. Cardiac abnormalities were completely resolved in all except two cases. CONCLUSIONS: Myocardial involvement can be seen during acute disease, but MIS-C generally does not lead to prominent damage during a year of surveillance. Cardiac magnetic resonance is a valuable tool to evaluate the degree of myocardial involvement in cases with MIS-C.

Adolescents With Breakthrough COVID-19 Infections Requiring Hospitalization: A Multicenter Retrospective Study.

Background Vaccines have the most important role in the battle against the COVID-19 pandemic. With the widespread use of vaccines, COVID-19 has remarkably declined. Adolescents were vaccinated after approvals for this age group, which was later than adults, and a nationwide vaccination program was implemented in August 2021 in Turkey for adolescents ≥12 years of age. Therefore, we aimed to determine the effects of the COVID-19 nationwide adolescent vaccination program on adolescent hospitalizations due to COVID-19 and multisystem inflammatory syndrome in children (MIS-C) by comparing two periods, including the vaccination period (VP) and the pre-VP (PVP). The second aim of this study is to compare the clinical features and disease severity of vaccine-breakthrough COVID-19 hospitalizations with unvaccinated individuals in the VP. Methods A retrospective multicenter study was conducted to determine and compare the number of hospitalizations due to COVID-19 and MIS-C between the VP (September 1, 2021, to August 31, 2022) and PVP (September 1, 2020, to August 31, 2021). We also compared the characteristics, risk factors, and outcomes of breakthrough infections of adolescents aged 12-18, which required hospitalization with the same age group of unvaccinated hospitalized individuals during the VP. Results During the study period, 3967 children (0-18 years) were hospitalized in the PVP and 5143 (0-18 years) in the VP. Of them, 35.4% were adolescents (12-18 years) in the PVP, and this rate was 18.6% in the VP; relative risk was 0.6467 (95% confidence interval [CI]: 0.6058-0.6904; p < 0.001). Patients with breakthrough COVID-19 were older (201 vs. 175 months, p < 0.001) and less commonly hospitalized for COVID-19 (81.5% vs. 60.4%, p < 0.001, odds ratio [OR]: 0.347 [95% CI: 0.184-0.654]). The majority of these infections were asymptomatic and mild (32% vs.72.9%: p < 0.001, OR: 5.718 [95% CI: 2.920-11.200]), and PICU admission was less frequently required (p = 0.011, OR: 0.188 [95% CI: 0.045-0.793]). Most breakthrough COVID-19 infections occurred within three months after the last vaccine dose (54.2%). Conclusions This study demonstrated a significant decrease in adolescent hospitalizations due to COVID-19 and MIS-C after implementing COVID-19 vaccines in Turkey. Breakthrough cases were less severe and mostly occurred three months after the last dose. This study emphasizes the importance of COVID-19 vaccines and that parents' decisions may be changed, particularly those who hesitate to or refuse vaccination.