ABSTRACT
COVID-19 presents potential risks for patients with channelopathies. A combination of many proarrhythmogenic factors, including hyperthermia, stress, hypoxia, electrolyte disturbances, diarrhea, as well as currently used drugs for the treatment of infection could be a potential cause of prolongation of the QTc interval and lead to life-threatening arrhythmias. Therefore, patients with LQTS should exercise special caution and when infected with COVID-19, their hospitalization in a hospital is desirable for adequate monitoring of the QTc interval. Particular diagnostic difficulties are caused by patients with a predisposition to prolongation of the QT interval and the presence of transient or latent prolongation of the QTc interval. The authors present a clinical case of a 29-year-old patient who, against the background of hyperthermia, diarrhea and vomiting caused by COVID-19, had recurrent presyncopal episodes and palpitations. The diagnosis of transient LQTS in the patient was established on the basis of episodes of QTc prolongation up to 609 ms with manual assessment of ECG monitor against a background of tachycardia of more than 120 bpm. The LQTS probability score on the Schwartz scale was 4.0 points. A molecular genetic study revealed a combination of several rare genetic variants with uncertain significance in the genes KCNE1, HCN4 and ANK2 encoding ion channels and associated with channelopathy and cardiac arrhythmias. The combination of several genetic variants could play a significant role both in the variability of the expression of the disease phenotype and in the diversity of responses to various provoking factors caused by COVID-19. © 2022, Professionalnye Izdaniya. All rights reserved.