Temporal Association Between Aromatase Inhibitor Initiation and New-Onset Atrial Fibrillation: A Case Report

Introduction: Breast cancer is the most prevalent cancer among women worldwide with a higher probability of diagnosis in the postmenopausal years. Aromatase inhibitors (AIs) block the aromatase enzyme responsible for converting androgens into estrogens in the peripheral tissues, which become the main source for estrogen production in this population. Estrogen plays a key role in promoting vasodilation and inhibiting vascular injury and atherosclerosis development. Reduced levels can contribute to adipocyte hyperplasia, insulin resistance, and dyslipidemia, all of which are risk factors for atrial fibrillation. Patient Case: We describe the case of a 71-year-old postmenopausal female who presented to the emergency department with shortness of breath and was subsequently diagnosed with new-onset atrial fibrillation. This case report aims to evaluate whether there is a potential correlation between the initiation of an AI and the development of atrial arrhythmias. Discussion: While existing data suggest an association between AI use and atrial fibrillation, there lacks an elaborate understanding of the temporal relationship between the 2. This case highlights a potential association between AI therapy and unusually rapid-onset atrial fibrillation, demonstrating the need for further research and increased clinical awareness when managing patients receiving these treatments.