Attending Memorial Sloan Kettering Cancer Center New York, United States
Introduction: Intravenous Immunoglobulin (IVIG) is an effective, well recognized treatment used to manage a broad range of immune mediated conditions. Of the cardiac side effects of IVIG, arrhythmias, hypotension and even myocardial infarction are noted as the most severe but are usually seen in patients with underlying cardiac pathologies. We discuss a rare case of severe but asymptomatic bradycardia following the administration of IVIG in a patient with Myasthenia Gravis and no cardiac history.
Description: 44 year old female with metastatic muscle-invasive neuroendocrine bladder cancer, presented to our hospital for dysphagia, globus sensation and dysphonia. Esophogram demonstrated pooling of contrast in the vallecula without evidence of obstruction, and laryngoscopy was negative for any abnormalities. She then had progression of symptoms with new diplopia, left 6th cranial nerve palsy and a sensation of “heavy tongue”. Her head CT was negative, and EMG suggested post-synaptic neuromuscular disorder, possibly myasthenia gravis. She was then started on dexamethasone and, one day later, IVIG. Two hours after receiving IVIG, her heart rate began to drop. She received IVIG for five days and during this time her heart rate continued to decline. From a baseline heart rate in the 60’s-70’s, her heart rate went as low as 24 with an average heart rate of 46. Cardiac work up was negative; EKG showed sinus bradycardia, the patient remained normotensive and asymptomatic. She was monitored in the ICU and then in the step-down setting with no acute events. Following completion of IVIG, her heart rate improved, and she was discharged on a steroid taper. On outpatient follow up her heart rate was in the normal range.
Discussion: In general, the cardiac side effects of IVIG are typically noted in patients who have inherent cardiac pathology, and of the cardiac side effects, bradycardia is extremely rare. On literature review, there have been only two reported cases of IVIG induced bradycardia in patients without a cardiac history. This case report, along with the two previously indicated cases, represents a growing body of evidence that IVIG induced arrhythmias, particularly bradycardia, may be more common than previously thought in patients without a cardiac history.
