1. Introduction
Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation, which mainly affects the peripheral joints with symmetric distribution1. Cardiovascular diseases (CVDs) are some of the leading causes of death in patients with RA2. In fact, the risk of sudden cardiac death was doubled in patients with RA compared to those without RA3,4. Pathological findings in cardiovascular examinations are frequently observed during the course of RA and are important factors that contribute to mortality2,3. Several studies have reported that patients with RA have a higher risk of developing atherosclerosis and cardiac arrhythmias5,6. RA is not only involved in the development of CVDs but also accelerates disease progression. Clinical and pathological evidence suggest that RA may be associated with chronic inflammation and immune dysregulation during the disease course7,8.
Electrocardiography (ECG) changes have been reported in patients with RA and other autoimmune diseases. For example, ST-T abnormalities have been observed in patients with systemic lupus erythematosus (SLE), and corrected QT (QTc) prolongation was observed in patients with RA and SLE9. Although the mechanisms for such changes have not been elucidated, it is suggested that systemic inflammation may directly result in electrophysiological changes or indirectly result in structural changes of the heart; these changes are associated with arrhythmias and/or worse cardiovascular outcomes in both the general population and RA patients5.
In this study, we aimed to investigate the ECG characteristics of patients with RA and the association between QTc interval and disease activity in these patients using a Japanese population-based RA cohort, the Kyoto University Rheumatoid Arthritis Management Alliance (KURAMA) study.