Case Presentation: A 40-year-old male with a biopsy-proven, signal recognition particle (SRP) positive necrotizing autoimmune myositis (NAM) being treated with abatacept, presented to the hospital with a two-day history of worsening shortness of breath. On arrival to the hospital, vital signs were remarkable for a heart rate of 170/ min. The physical exam was unremarkable. Lab work revealed troponin of 0.72 ng/mL, creatinine phosphokinase at 691 IU/L(normal range), and aldolase at 23.5 U/L (normal range less than 8.1 U/L). His electrocardiogram revealed a new-onset atrial flutter with variable conduction, with an underlying right bundle branch block. A computed tomography angiography of the chest was notable for multiple right-sided pulmonary emboli. Infectious workup including the COVID-19 test was unremarkable. Transthoracic echocardiography (TTE) revealed a reduced left ventricular ejection fraction (LVEF) of 10%. A prior TTE from three years ago showed a normal LVEF. The patient was treated with amiodarone infusion for atrial flutter and started on low molecular weight heparin for anticoagulation. One day later the patient became hypotensive, requiring pressor support. Transesophageal echocardiography followed by direct cardioversion was attempted, and the patient suffered a cardiac arrest requiring escalating ionotropic support and eventual extracorporeal membrane oxygenation (ECMO). Cardiac magnetic resonance imaging revealed diffuse late gadolinium enhancement suggestive of ischemic cardiomyopathy. A left heart catheterization revealed non-obstructive coronary arteries. Due to the rapidly progressive course of the patient’s cardiac complications, NAM with cardiac involvement was considered and treatment with pulse dose steroids and cyclophosphamide was initiated. Within three weeks, a repeat TTE revealed improvement of LVEF to 55%, and the patient was successfully weaned off ECMO. Four weeks later the patient was discharged on steroids and cyclophosphamide to a long-term acute care facility.
Discussion: Cardiac manifestations have been reported with idiopathic inflammatory myopathies (IIM) such as polymyositis and dermatomyositis [1]. Similarly, in rare cases, NAM can also be associated with cardiac complications like other IIM [2]. Cardiac involvement is a common cause of morbidity and mortality in patients with IIM and is a poor prognostic factor [1]. We argue that early recognition and hence appropriate management with immunologic agents and steroids, such as in our patient, can potentially be lifesaving.
Conclusions: Clinicians should have a high-suspicion for NAM-associated cardiac complications and potentially monitor these patients with telemetry, as prompt treatment with immunologic agents and steroids portends a good prognosis.