Fulminant eosinophilic myocarditis and doxycycline administration: a case report.

Background: Eosinophilic myocarditis is a life-threatening condition with a heterogeneous clinical presentation and aetiology. Cases of drug-induced or parasitic myocarditis have been reported but there is scant literature on the involvement of treatments, such as doxycycline, and eosinophil degranulation due to parasitic lysis. Case summary: Here, we report the case of a 59-year-old man without a relevant past medical history who developed a skin rash with hepatic cytolysis and mild eosinophilia. No aetiology was found despite an exhaustive work-up, but a parasitic infestation was suspected in view of the patient's daily contact with freshwater environments. A few days after doxycycline administration, the patient's clinical state worsened rapidly leading to a ventricular electrical storm-related cardiogenic shock requiring mechanical support. After initiation of high-dose corticosteroid therapy, cardiac function normalized promptly allowing for withdrawal of the mechanical support. An endomyocardial biopsy led to the diagnosis of eosinophilic myocarditis, which was congruent with the cardiac magnetic resonance imaging data. Discussion: The main aetiologies reported for eosinophilic myocarditis are often allergic reactions, such as DRESS syndrome in developed countries, or infections, especially due to parasites in other countries. Drugs such as tuberculosis medications, antipsychotics, and antiepileptics have been implicated, as well as antibiotics, e.g. minocycline, but there has been no case of doxycycline-related eosinophilic myocarditis reported to date. Parasitic lysis is known to induce the activation of eosinophils and their on-site degranulation but no case has been reported on myocarditis due to parasitic lysis after administration of antiparasitic drugs.