Myasthenic Crisis Unmasking Myocardial Infarction with Nonobstructive Coronary Arteries in a Patient with Undiagnosed Myasthenia Gravis.

We present a case of a patient with undiagnosed myasthenia gravis presenting in myasthenic crisis. In this case, the patient presented primarily with myocardial infarction with nonobstructive coronary arteries and respiratory failure and was later diagnosed to be in myasthenic crisis. The myasthenic crisis was treated with intravenous immunoglobulin (IVIg) and corticosteroids. Given the inadequate response to IVIg and glucocorticoids, the patient was subsequently administered an anti-CD20 monoclonal antibody in the form of rituximab. The patient responded well to rituximab, and her cardiac function subsequently improved.