Background: The current epidemic of B19V myocarditis in young children with a clinical picture
of severely impaired left ventricular function and massive myocardial inflammation,
which often persists for months, faces new therapeutic immunomodulatory challenges
combating this inflammation and preventing further remodeling of the myocardium.
Methods: Patients with biopsy-confirmed B19V myocarditis enrolled from August 2023 to September
2024 within the multicenter registry for pediatric myocarditis “MYKKE” and receiving
immunomodulatory therapy with anakinra or interferon β were collected.
Results: Due to insufficient improvement in cardiac function with optimal heart failure therapy,
the need to consider other therapies arose in 13 out of 40 (33%) registered patients
with B19V myocarditis in seven participating centers. These patients were characterized
by a young median age of 1.5 (1.0–2.0) years and 58% were female (7/12). They experienced
a severe disease course with an initial left ventricular ejection fraction (LVEF)
of 22 (20–26)%. Seven patients (54%) required mechanical circulatory support and no
patient died. Endomyocardial biopsy (EMB) revealed acute/subacute myocarditis in all
(11/11), with data for two patients pending. Myocardial B19V copies were elevated
with 6,878 (3,633–43,173) copies/μg cardiac DNA. All received intravenous immunoglobulin,
in part repeatedly. Eight patients were treated with anakinra only, three are still
on therapy. In two, anakinra therapy was stopped after 2 weeks seeing no LVEF improvement.
In two out of four with anakinra therapy (8 weeks) and ventricular assist device (VAD),
VAD was weaned. One patient was treated for 6 weeks with anakinra and afterward with
Cyclosporin A for 3 months due to ongoing inflammation and recovered fully. Interferon
has been used in four patients for 2 to 3 weeks so far, one was treated before with
anakinra for 2 weeks and also received corticosteroids. Next to the weaned patients,
the LVEF at follow-up (FU) was slightly better (median of 10 LVEF points) in five
patients. One patient presented with a decreased LVEF from 26% to 20% after 2 weeks
of anakinra therapy. Further follow-up data are pending.
Conclusion: In these cases, with severe acute lymphocytic B19V-induced myocarditis immunomodulatory
therapies appear to be a promising option for reducing myocardial inflammation and
interrupting the vicious circle of cardiac remodeling triggered by it. Statements
on efficacy and outcome must be awaited at this time. Nevertheless, there is also
a need for harmonization to make outcome data comparable.
