Abstract: Journal of Electrocardiology 62 (2020) 59–64 Contents lists available at ScienceDirect Journal of Electrocardiology journal homepage: www.jecgonline.com The effect of 5-day course of hydroxychloroquine and azithromycin combination on QT interval in non-ICU COVID19(+) patients Nijad Bakhshaliyev, MD ⁎, Mahmut Uluganyan, MD, Asim Enhos, MD, Erdem Karacop, MD, Ramazan Ozdemir, MD Bezmialem Vakif University, Department of Cardiology, Turkey a r t i c l e i n f o Keywords: Hydroxychloroquine Azithromycin Electrocardiography Coronavirus disease 2019 QT interval a b s t r a c t Background: The combination of Hydroxychloroquine (HCQ) and azithromycin showed effectiveness as a treatment for COVID-19 and is being used widely all around the world. Despite that those drugs are known to cause prolonged QT interval individually there is no study assessing the impact of this combination on electrocardiography (ECG). This study aimed to assess the impact of a 5-day course of HCQ and azithromycin combination on ECG in non-ICU COVID19(+) patients. Methods: In this retrospective observational study, we enrolled 109 COVID19(+) patients who required non-ICU hospitalization. All patients received 5-day protocol of HCQ and azithromycin combination. On-treatment ECGs were repeated 3-6 h after the second HCQ loading dose and 48-72 h after the first dose of the combination. ECGs were assessed in terms of rhythm, PR interval, QRS duration, QT and QTc intervals. Baseline and ontreatment ECG findings were compared. Demographic characteristics, laboratory results were recorded. Daily phone call-visit or bed-side visit were performed by attending physician. Results: Of the 109 patients included in the study, the mean age was 57.3 ± 14.4 years and 48 (44%) were male. Mean baseline PR interval was 158.47 ± 25.10 ms, QRS duration was 94.00 ± 20.55 ms, QTc interval was 435.28 ± 32.78 ms, 415.67 ± 28.51, 412.07 ± 25.65 according to Bazett's, Fridericia's and Framingham Heart Study formulas respectively. ΔPR was −2.94 ± 19.93 ms (p = .55), ΔQRS duration was 5.18 ± 8.94 ms (p = .03). ΔQTc interval was 6.64 ± 9.60 ms (p = .5), 10.67 ± 9.9 ms (p = .19), 14.14 ± 9.68 ms (p = .16) according to Bazett's, Fridericia's and Framingham Heart Study formulas respectively. There were no statistically significant differences between QTc intervals. No ventricular tachycardia, ventricular fibrillation or significant conduction delay was seen during follow-up. There was no death or worsening heart function. Conclusion: The 5-day course of HCQ- AZM combination did not lead to clinically significant QT prolongation and other conduction delays compared to baseline ECG in non-ICU COVID19(+) patients. © 2020 Elsevier Inc. All rights reserved.