Association between cumulated hydroxychloroquine in systemic lupus erythematosus and development of cardiac conduction alterations

Background/Introduction Hydroxychloroquine (HCQ) is a widely used drug in Systemic Lupus Erythematosus (SLE). It may cause cardiac alterations which includes short term arrhythmic events (via QT interval prolongation) and medium-late term dose dependent cardiomyopathy1. The few research articles published on the medium-late term effects of HCQ in cardiac conduction disorder do not show relevant alterations. Purpose To assess the effect of HCQ in cardiac conduction in a consecutive SLE population. Methods Observational, single University hospital study of all consecutive SLE patients with an electrocardiogram (EKG) at HCQ onset and at least one EKG in follow-up, with a period of at least 3 months on HCQ treatment was performed. We assessed conduction alteration by electrocardiogram (EKG), defined as any degree of atrio-ventricular block or bundle branch block. The EKGs were gathered from the clinical history and interpreted at the beginning of the treatment and during the 15.2 years (CI95% 13.24–17.16) follow-up period. We defined cumulated HCQ (cHCQ) as the multiple of the mean annual dose of the sample. Results We studied 109 (96 women/ 13 men) SLE patients with a mean (±.SD) age of 61 ±. 2.78 years. A statistically significant association was observed between the cHCQ, and the development of cardiac conduction alterations [OR 1.1 CI95% 1.02–1.19; p=0.011] (Table & Figure). A total of 8 covariates were included. Among them, those that had the greatest influence on the development of the primary event were previous conduction alterations [OR 4.15 CI95% 6.39–624.54; p Conclusion According to our study, it seems to be an association between the cHCQ and development of cardiac conduction alterations regardless of other variables evaluated. Wider longitudinal studies are required with a protocolized EKG performance in successive visits to further analyze this association. Funding Acknowledgement Type of funding sources: None.