An Outbreak of Myocarditis and Asymptomatic Troponinemia in Children Following Parvovirus B19 Infections in Northern Greece and a Scoping Review.

BACKGROUND

Parvovirus B19 (B19V) has frequently been followed by cardiac involvement in the form of myocarditis, with potential progression towards dilated cardiomyopathy. In children, B19V-related myocarditis is associated with high morbidity and mortality.

METHODS

We describe a cluster of cases of B19V infections complicated with myocardial injury that presented either as transient asymptomatic elevation of cardiac troponin or as full-blown myocarditis in young children. These cases emerged during an outbreak of B19V infections in spring/summer 2024 in Northern Greece. In addition, a scoping review of pertinent published case reports and case series was conducted.

RESULTS

After a fatal index myocarditis case in a 3.5-year-old girl complicating B19V infection, 65 children who had a clinically diagnosed and/or microbiologically confirmed B19V infection presented with myocardial injury of various degrees. Increased high-sensitivity troponin levels without any myocarditis symptoms or signs were found in 52/65 (80%) children. Seven (10.8%) had self-limiting acute myocarditis with high troponin levels and 6 (9.2%) were diagnosed with fulminant myocarditis, of which 2 had a fatal outcome. Median age of all participants was 4.0 [interquartile range (IQR) 3.0-6.5] years. Median troponin in 6 children with dilated cardiomyopathy was 1900 (IQR 575-4500) ng/L, while in asymptomatic children it was 129.5 (IQR 89.5-244) ng/L. Thirty-two relevant studies, mainly case reports or small series, were found with an additional 191 cases (≥60 fatalities).

CONCLUSIONS

Emergence of myocardial injury during outbreaks of B19V infections may occur. Awareness of this cardiac complication may facilitate early optimal management of rare but life-threatening complications, such as fulminant myocarditis.