Transient sinus bradycardia during the course of MIS-C

Following COVID-19 infection, multisystem inflammatory syndrome in children (MIS-C) presents as a hyperinflammatory condition affecting multiple organ systems. We observed that many of the patients have bradycardia in the course of the disease.

In a retrospective analysis of medical records from June 2020 to July 2023, we investigated the clinical course of MIS-C. Clinical recovery day was defined as the point at which there was an absence of fever (≥38°C) and no further need for vasoactive inotropes or respiratory support. The relationship between clinical recovery day and bradycardia and its implications for clinical course and prognosis was examined in this study.

The study included 46 patients diagnosed with MIS-C with a mean age of 10.06 ± 4.06 years. The median time of clinical recovery was 4.0 (IQR = 1.0) days. Asymptomatic sinus bradycardia developed in 36 (78.3%) patients at a median duration of 4.0 (IQR = 2.0) days in the follow-up period. There was a strong positive correlation (ρ = 0.701, p < 0.001) between the onset of bradycardia and clinical improvement. There was a strong positive correlation between the onset of bradycardia and clinical improvement in patients with cardiac involvement (ρ = 0.590, p = 0.026) and a very strong positive correlation in patients with no cardiac involvement (ρ = 0.765, p < 0.001).

Evidence suggests potential associations between the onset of bradycardia and clinical recovery in the course of MIS-C. Large-scale multicenter studies are needed to validate our findings and elucidate its clinical significance.