Cardiac arrest in seronegative idiopathic inflammatory myopathy: a case report

Idiopathic inflammatory myopathies (IIMs) are autoimmune diseases that are characterized by muscle injury. These disorders can cause cardiomyopathy and heart failure, myocarditis, and arrhythmias. However, only a few cases of cardiac arrest as a result of IIMs have been previously reported.

A 46-year-old male presented with an out-of-hospital ventricular fibrillation cardiac arrest. A diagnosis of IIM had been made through a muscle biopsy performed 2 years before presentation. The patient had a positive anti-nuclear antibody but negative myositis-specific antibodies. His initial symptoms of IIM were mild and consisted of myalgias. His only cardiac symptoms were minor palpitations that occurred 3 years prior to the cardiac arrest, with a negative Holter monitor test result at that time. His cardiac catheterization was normal. He was suspected to have myocarditis, and a rheumatologist was consulted, following which the patient was initiated on intravenous immunoglobulin (IVIG). Cardiac magnetic resonance imaging demonstrated evidence of chronic myocarditis and an ejection fraction of 44%. He was initiated on goal-directed medical therapy for heart failure. A VVI implantable cardioverter defibrillator was implanted for secondary prevention. He was discharged and prescribed additional immunosuppression including further IVIG infusions, prednisone taper and rituximab infusions.

Our case demonstrates that cardiac arrest in IIM is not only plausible, but can be the first major cardiac manifestation of the disease. When a diagnosis of IIM is made, patients require a thorough assessment of cardiac symptomatology and a low threshold for additional cardiac investigations.