Methylprednisolone-Induced Symptomatic Sinus Bradycardia in a Multiple Sclerosis Patient: A Case Report

Intermittent high-dose methylprednisolone therapy is widely used for various autoimmune conditions treatment. Common side effects are well known and monitored carefully during therapy. Although cardiovascular adverse events are uncommon, they have been increasingly reported in the literature. This is a case of a 30-year-old female who developed symptomatic sinus bradycardia after receiving three grams of intravenous methylprednisolone pulse therapy for multiple sclerosis flare-ups. Her pulse rate reached 40bpm, together with lightheadedness and chest tightness. An electrocardiogram confirmed sinus bradycardia, for which she was initially managed by splitting the methylprednisolone dose in half; however, 12 hours later, the heart rate decreased further to 35bpm, and her symptoms worsened. Subsequently, the medicine was omitted, and the patient shifted to the intensive care unit for close observation and monitoring. She was treated conservatively with close observation resulted in a gradual normalization of the heart rate. The diagnosis of methylprednisolone pulse-induced bradycardia was made after excluding other common etiologies of sinus bradycardia. This case report aims for careful cardiovascular monitoring in patients receiving high doses of methylprednisolone due to the dose-dependent cardiovascular risks.