Eosinophilic myocarditis complicated by permanent atrioventricular nodal block: a case report

BACKGROUND: Eosinophilic myocarditis (EM) is a rare disease with different clinical pictures and disease courses. Little literature is available on the various courses of the disease. CASE SUMMARY: A previously healthy 44-year-old male patient presented with acute heart failure and developed complete atrioventricular (AV) block requiring pacing. Acute heart failure was managed with inotropic support, non-invasive ventilation, and implantation of a permanent AV-sequential pacemaker. Cardiac magnetic resonance imaging was suggestive of myocarditis and endomyocardial biopsy diagnosed EM histologically. Endomyocardial biopsy was essential for definite aetiologic assignment, thus dispelling initial reservations about immunosuppressive therapy. Final treatment strategy consisted of steroids and Azathioprine. DISCUSSION: Endomyocardial biopsy is essential to establish diagnosis and targeted treatment in EM, which can rapidly lead to life-threatening conditions. Left ventricular function recovered within 2 weeks in response to immunosuppression and the patient was consistently well during follow-up. Despite the otherwise good response to immunosuppression, complete AV block continued over time.