Hydroxychloroquine & QT Prolongation

A cohort of 90 COVID-19 patients admitted to a Boston hospital, all of whom received hydroxychloroquine, with or without azithromycin. Some 19% who received hydroxychloroquine monotherapy developed prolonged QTc of 500 ms or more; 3% had a change in QTc of 60 ms or more. With hydroxychloroquine plus azithromycin, the rates were 21% and 13%, respectively. One patient with QTc prolongation developed torsades de pointes. The authors note that without a control group, they could not rule out cardiotoxicity from COVID-19 as opposed to hydroxychloroquine and azithromycin. 

https://jamanetwork.com/journals/jamacardiology/fullarticle/2765631

In a study of 40 COVID-19 patients admitted to a French ICU who received hydroxychloroquine, over 90% experienced increased QTc interval. One third of those who received hydroxychloroquine plus azithromycin developed QTc of 500 ms or more, versus 5% of those who received hydroxychloroquine alone. There were no ventricular arrhythmias.

https://jamanetwork.com/journals/jamacardiology/fullarticle/2765633