Introduction Cardiac manifestations and polyneuropathy in lupus are common, although clinically manifest myocarditis is rare, estimated at 9%.

Case report Female patient 44 years old came to the Emergency Department due to general weakness and dizziness. She has lost 14 kg in the last 3 months, she has subfebrility, fatigue, hair loss, joint pain. A cardiac arrest with ventricular fibrillation (VF) occurred during the examination. Successful resuscitation was performed. Echocardiography indicates an ejection fraction (EF) of 5% and contractility disorder. Mechanical circulatory support to venous-arterial extracorporeal membrane oxygenation (V-A ECMO) was introduced. Extensive cardiac treatment and work up was done, coronarography (normal), myocardial biopsy (lymphocytic myocarditis less likely gigantocellular), pericardial biopsy (chronic pericarditis), lysis of pericardial adhesion with improvement in EF. Cardiac MRI verifies diffuse inflammatory myopericarditis. The serology on Chlamidophila pneumonie was positive. Tetracycline therapy was started. Asymmetric tetraparesis occurred during cardiac treatment, muscle biopsy was without inflammatory infiltrate, cervical and thoracic spine MR was normal, EMNG indicated polyneuropathy, and she was diagnosed with Critical illness polyneuropathy. There was a suspected ischemic lesion on the brain MR temporoparietally to the right. Thoracic CT was normal. In that moment, she was transferred to the Department of Immunology. The treatment was started according to cardiac guidelines for myocarditis, solumedrol 1 mg/kg, and 90 mg IVIG for 3 days after which she started recovering neuromuscular symptoms. Of the SLICC criteria she had nonscarring alopecia, arthritis, serositis, positive ANA, 1:320, homogenous, ds DNA, low complement (C3, C4). In maintenance therapy, she has a low dose of glucocorticoids, azathioprine 100 mg and has been in remission for 2 years.

Conclusion The patient had complications in unrecognized systemic lupus, critical illness polyneuropathy, infectious myocarditis and chronic constrictive pericarditis, who recovered only from cardiac support and medication. Accurate diagnosis in SLE-mimicking symptoms is possible with extensive diagnostics.