Changes in QTc interval after hydroxychloroquine therapy in patients with COVID-19 infection: a large, retrospective, multicentre cohort study.

Objective: To evaluate the extent of hydroxychloroquine-induced corrected QT (QTc) prolongation and its relation to COVID-19 infection severity and incidence of polymorphic ventricular arrhythmias and sudden arrhythmic deaths.

Design: A large-scale cohort study with retrospective analysis of baseline and on-therapy QT interval corrected using Bazett and Fridericia formulas.

Setting: A multicentre study involving eight secondary and tertiary care hospitals of the Abu Dhabi Health Services Company (SEHA), United Arab Emirates.