Study of 90 hospitalized patients given HCQ, 53 also receiving AZ, 53% hypertension, 29% diabetes mellitus, baseline median QTc 473ms for HCQ, and 442ms for HCQ+AZ. Median change for HCQ+AZ ΔQTc of 23ms vs. 5.5ms for HCQ. Other factors such as stress cardiomyopathy or myocarditis could not be ruled out. Without a control arm, they could not conclude that HCQ and AZ conferred increased cardiotoxic risk; however, compared with HCQ alone, ΔQTc differences were likely associated with the addition of AZ. The likelihood of prolonged QTc was greater in those who received concomitant loop diuretics or had a baseline QTc of 450 milliseconds or more. HCQ was discontinued in 10 patients due to adverse events including nausea, hypoglycemia, and 1 case of torsades de pointes. There were no deaths reported.Appropriate use and careful analysis of contraindications, risks, and benefits are important. More recent and much larger studies have not shown significant safety concerns, including outpatient RCTs showing no serious adverse events, and even the RECOVERY trial which used an unusually high dose of HCQ (including 237 patients also receiving AZ) reports they "did not show any excess in ventricular tachycardia (including torsade de pointes) or ventricular fibrillation in the hydroxychloroquine arm", and "serious cardiovascular toxicity has been reported very rarely despite the high prevalence of cardiovascular disease in hospitalized patients, the common occurrence of myocarditis in COVID-19, and the extensive use of hydroxychloroquine and azithromycin together."