Antimalarial use and arrhythmias in COVID-19 and rheumatic patients: a matter of dose and inflammation?

We read with great interest the paper by Graef and colleagues, ‘Festina lente: hydroxychloroquine, covid-19 and the role of the rheumatologist’.1 As the authors correctly point out, despite firm evidence that their efficacy and safety are lacking,2 antimalarials are being widely prescribed for the treatment of patients with COVID-19. This, as also underlined with some concern by the European League Against Rheumatism President Iain McInness,3 has rapidly led to antimalarial supply shortages worldwide, primarily affecting patients with rheumatic disease, such as those with systemic lupus erythematosus and rheumatoid arthritis (RA). In these groups, low-dose antimalarials (hydroxychloroquine up to 6 mg/kg/day and chloroquine up to 4 mg/kg/day) are the mainstay to control immunological response and to prevent flare in view of their favourable efficacy and safety profile. However, electrophysiological experiments in isolated cardiac preparations and animal models, and some case reports in rheumatic patients, have reported a proarrhythmic effect of antimalarials. Arrhythmias, potentially triggered by hypoxia, metabolic/electrolyte derangement and viral myocarditis, have been reported in 16.7% of hospitalised patients with COVID-19.4 While this suggests that antimalarial use may further …