Hydroxychloroquine or chloroquine (HCQ/CQ) as monotherapy or in combination with azithromycin was associated with increased reporting of serious cardiovascular adverse events, TdP/QTc prolongation, and ventricular arrhythmia. HCQ/CQ–azithromycin combination therapy was associated with higher reporting odds of cardiovascular events than was HCQ/CQ monotherapy.

Concurrent use of HCQ/CQ and QTc-prolonging agents or cytochrome P450 3A4 inhibitors may increase the odds of serious cardiovascular adverse events.

Cardiovascular risks need to be considered when evaluating the benefit/harm balance of the use of HCQ/CQ as monotherapy or in combination with azithromycin, especially when treating vulnerable patients with coronavirus disease 2019.