Recurrent atrial fibrillation after pulse corticosteroid treatment for a relapse of multiple sclerosis

•Atrial fibrillation is a rare but serious complication of high dose corticosteroids.•Dysautonomia may increase the risk of atrial fibrillation multiple sclerosis.•ECG monitoring should be advised during high dose corticosteroid treatment. Standard therapy for a relapse of multiple sclerosis is a high dose pulse corticosteroid therapy. Cardiovascular adverse events ranging from palpitations to serious arrhythmias like atrial fibrillation and ventricular tachycardia have been associated with this treatment. The underlying mechanism behind the development of atrial fibrillation and treatment of multiple sclerosis relapse with steroids is still unclear. In this case, a 27-year-old male with multiple sclerosis is presented who developed atrial fibrillation on two occasions following two consecutive treatments with high dose methylprednisolone for the treatment of multiple sclerosis relapse. Extensive work-up revealed mild sympathetic autonomic system dysfunction. Based on this case and previous studies, we propose that a disturbed function of the autonomic system increases the risk of atrial fibrillation and/or other arrhythmias in people with multiple sclerosis.