The question of COVID-19 and long-COVID-19 course in children remains unsolved. This infection in children, which is associated with COVID-19, can vary from asymptomatic to systemic damage of various systems. Multisystem inflammatory syndrome in children, associated with SARS-CoV-2 (MIS-C), is a serious condition in children and adolescents after experiencing COVID-19. Published data on MIS-C have indicated that the inflammation can be registered in the gastrointestinal tract (60–100%), as well as in cardiovascular (80%), nervous (29–58%), and respiratory (21–65%) systems. However, with the changing characteristics of SARS-CoV-2, the manifestations of COVID-19 and long-COVID-19 in children have also been changing. Currently, there is no clear understanding of the development of severe COVID-19 and MIS-C in children, especially after being exposed to patients with COVID-19. We presented two new clinical courses of multisystem inflammatory syndrome in children with severe multisystem damage after close contact to relatives with COVID-19 or long-COVID-19. Thus, high-risk children, who are positive for SARS-CoV-2 infection after contact with COVID-19 patients, should be clinically managed during the first few months. The identification of the disease complexity requires the involvement of neurologists, cardiologists, and other specialists.

Emery-Dreifuss muscular dystrophy (EDMD) is inherited muscle dystrophy often accompanied by cardiac abnormalities in the form of supraventricular arrhythmias, conduction defects and sinus node dysfunction. Cardiac phenotype typically arises years after skeletal muscle presentation, though, could be severe and life-threatening. The defined clinical manifestation with joint contractures, progressive muscle weakness and atrophy, as well as cardiac symptoms are observed by the third decade of life. Still, clinical course and sequence of muscle and cardiac signs may be variable and depends on the genotype. Cardiac abnormalities in patients with EDMD in pediatric age are not commonly seen. Here we describe five patients with different forms of EDMD (X-linked and autosomal-dominant) caused by the mutations in EMD and LMNA genes, presented with early onset of cardiac abnormalities and no prominent skeletal muscle phenotype. The predominant forms of cardiac pathology were atrial arrhythmias and conduction disturbances that progress over time. The presented cases discussed in the light of therapeutic strategy, including radiofrequency ablation and antiarrhythmic devices implantation, and the importance of thorough neurological and genetic screening in pediatric patients presenting with complex heart rhythm disorders.

The advent of the COVID-19, specialists are increasingly encountering previously unknown pathological conditions in their practice. For some time, we have believed that COVID-19 in children is most often mild and asymptomatic. However, with the passage of time and the accumulation of the experience, it became obvious that the new infectious disease it will be quite severe in children. Differential diagnosis of multiple organ disorders in children during the COVID-19 pandemic should be primary carried out with the Multisystem Inflammatory Syndrome in Children, associated with COVID-19 (MIS-C), as well as Long-COVID-19. According to published data, the manifestations of these conditions are due to frequent lesions of the gastrointestinal tract (60–100 %), cardiovascular (80 %), nervous (29–58 %) and respiratory (21–65 %) systems. At present, there is no exact idea of these pathological conditions, the criteria for their diagnosis and the tactics of managing children, not only at the stage of diagnosis, but also at the stage of observation. The authors present a diagnostically complex clinical case describing the development of multiple organ damage in a 7-year-old child after contact with a mother who was sick with COVID-19. The data on the course features, the results of the examination and the difficulties of differential diagnosis of this case with other diseases with a similar clinic are summarized.

Background. The problem of managing children with hypertrophic cardiomyopathy (HCM) remains relevant due to the high risk of sudden cardiac death (SCD). Registers of patients with HCM contribute to a better understanding of the course of the disease and its outcomes.Objective. To study the structure of CMP with a hypertrophic phenotype, as well as to identify clinical, molecular and genetic features of the course of HCM and outcome in children based on anamnestic, clinical and instrumental data from an electronic database.Design and method/ Currently, the database includes complete information on 80 children from 0 to 18 years of age inclusive with a hypertrophic phenotype of CMP. The study was performed on the basis of the Department of Pediatric Cardiology and Medical Rehabilitation of the V.A. Almazov” of the Ministry of Health of Russia. The database contains the history of the disease and family history, the results of clinical and laboratory-instrumental examination, the results of molecular genetic research. The register is dynamically updated.Results. The mean age of onset of HCM was 1.75 [0.02; 10.00] years. There were more boys than girls — 54 (67.5 %). The main complaints were decreased exercise tolerance in 35 (43.8 %) children and shortness of breath in 30 (37.5%) children. All children had signs of heart failure (HF): 53 (66.3 %) had signs of functional class 2 HF, 26 (32.5 %) — functional class 1 and 1 (1.2 %) — functional class 3. Ventricular arrhythmias were recorded in 23 (29 %) children, unstable ventricular tachycardia in 2 (2.5 %) children. Myocardial fibrosis of the left ventricle according to the results of MRI of the heart was found in 60.7 %. A lethal outcome was registered in 5 % (n = 4) of cases on average at 241 ± 117 days of life. All the deceased had phenocopies of HCM.Conclusion. Maintaining an electronic database of patients with HCM will allow a better understanding of the influence of factors, including genetic ones, on the course, outcomes, and prognosis of the disease in the pediatric population.

This article describes a rare clinical manifestation of arrhythmogenic cardiomyopathy in a 13-year-old boy - the “hot phase”, characterized by severe chest pain and a significant increase on a level of troponin I. The clinical case demonstrates the difficulties of the differential diagnosis of this disease and an importance of an integrated approach to examination of the patient, including cardiac magnetic resonance imaging and genetic testing.