To describe a case of myo/pericarditis in a patient with Myasthenia Gravis and thymoma.

Cardiac involvement has been reported in patients with myasthenia gravis. Manifestations include pericarditis, giant-cell-myocarditis, Takotsubo cardiomyopathy, and arrhythmias. Myocarditis and pericarditis are associated with thymomas. Though the exact pathogenesis is unclear, cardiac involvement has been associated with the production of antibodies against striated muscle, including anti-titin and anti-ryanodine, anti-mitochondrial-7, anti-smooth-muscle-alpha and anti-citric-acid-extract. Prognosis is varied; however, myocarditis associated with myasthenia gravis can be rapidly fatal.

A 27-year-old male with newly diagnosed generalized acetylcholine-receptor-antibody-positive myasthenia gravis with underlying thymoma without prior cardiac history was admitted to the ICU for acute type-2 respiratory failure secondary to myasthenic crisis. He was recently treated with a complete course of IVIG.  Rapid taper of oral prednisone, and concurrent infection possibly resulted in the current crisis.

The patient had a screening Echocardiogram and was found to have reduced cardiac ejection-fraction of 40%. His anti-striational antibodies were negative. He did not have co-existing polymyositis and his CK was normal. Cardiac MRI however, (performed after Plasma Exchange) revealed pericarditis.

He was extubated and discharged on Prednisone 60 mg/day. Repeat Echocardiogram (after Plasma Exchange) showed return of myocardial function to normal (EF 68%). He underwent successful video-assisted-thoracoscopic-thymectomy and is currently on a slow taper of steroids.