Hydroxychloroquine cardiotoxicity: a case-control study comparing patients with COVID-19 and patients with systemic lupus erythematosus

Antimalarials have been associated with QT prolongation in COVID-19 patients but are generally safe in systemic lupus erythematosus (SLE).We compared the prevalence of QTc prolongation between COVID-19 and SLE patients treated with hydroxychloroquine (HCQ).We included patients with SARS-CoV-2 infection confirmed by nasopharyngeal swab and patients taking HCQ for SLE. A prolonged QTc was defined as an increase in QTc intervals60 ms (compared with baseline) or as a QTc of ≥500 ms. We performed the univariate and multivariate logistic regression to investigate the risk factors for QTc prolongation in COVID-19 patients.We enrolled 58 COVID-19 patients (median age 70.5 years, IQR 25), grouped into group A (patients with HCQ) group B (patients with HCQ + azithromycin) and group C (not received either drug). Fifty (26%) COVID-19 patients presented a QTc prolongation (12 QTc≥500 ms, 3 patients ΔQTc60 ms). We did not find any differences in QTc prolongation among the three treatment groups. Baseline QTc (OR 111.5) and D-dimer (OR 78.3) were independently associated to QTc prolongation. Compared to the 50 SLE patients (median age 38.5 years, IQR 22), chronically treated with HCQ, COVID-19 patients showed significantly longer QTc (p0.001).This is the first study demonstrating that, unlike COVID-19 patients, patients with SLE are not susceptible to HCQ-induced long QT syndrome and arrhythmia. The combined arrhythmogenic effect of SARS-CoV-2 infection and HCQ could account for the excess of QTc prolongation and fatal arrhythmias described in patients with COVID-19.