PT  - JOURNAL ARTICLE
AU  - Gongxin Wang
AU  - Chieh-Ju Lu
AU  - Andrew W. Trafford
AU  - Xiaohui Tian
AU  - Hannali M Flores
AU  - Piotr Maj
AU  - Kevin Zhang
AU  - Yanhong Niu
AU  - Luxi Wang
AU  - Yimei Du
AU  - Xinying Ji
AU  - Yanfang Xu
AU  - Dan Li
AU  - Neil Herring
AU  - David Paterson
AU  - Christopher L.-H. Huang
AU  - Henggui Zhang
AU  - Ming Lei
AU  - Guoliang Hao
TI  - Mechanistic insights into ventricular arrhythmogenesis of hydroxychloroquine and azithromycin for the treatment of COVID-19
AID  - 10.1101/2020.05.21.108605
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.05.21.108605
4099  - http://biorxiv.org/content/early/2020/05/22/2020.05.21.108605.short
4100  - http://biorxiv.org/content/early/2020/05/22/2020.05.21.108605.full
AB  - Background Recent reports on the use of hydroxychloroquine (HCQ) alone, or combined with azithromycin (AZM) in the management of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have raised cardiac safety concerns. Currently, there is limited mechanistic data evaluating cardiac safety with HCQ and AZM therapy.Methods Using comprehensive In Vitro ProArrhythmia Assay (CiPA) Schema IC50 paradigms, we examined the cardiac electrophysiological effects of HCQ and HCQ/AZM. Molecular modelling explored HCQ and AZM binding properties to hERG. Langendorff-perfused guinea-pig hearts were electrically and optically mapped by multi-electrode array and voltage (RH237) and Ca2+ (Rhod-2 AM) dyes. Human action potential and ion current reconstructions were performed in silico.Results HCQ blocked IKr and IK1 with IC50 concentrations (10±0.6 and 34±5.0 μM) within the therapeutic range observed clinically. HCQ also blocked INa and ICaL but at higher IC50, whilst Ito and IKs were unaffected. Contrastingly, AZM produced minor inhibition of INa, ICaL, IKs, and IKr,, with no effect on IK1 and Ito. HCQ + AZM combined inhibited IKr and IK1 with IC50s of 7.7 ± 0.8 μM and 30.4 ± 3.0 μM, but spared INa, ICaL and Ito,. Molecular modelling confirmed potential HCQ binding to hERG. Cardiac mapping and ECG studies in isolated hearts demonstrated that HCQ slowed heart rate and ventricular conduction with associated prolongation of PR, QRS and QT intervals. Optical mapping demonstrated, and prolonged, more heterogeneous, action potential durations and intracellular Ca2+ transients. These effects were accentuated with combined HCQ+AZM treatment, which elicited electrical alternans, re-entrant circuits and wave breaks. Reconstruction in a human in-silico model demonstrated that this is attributable to the integrated action of HCQ and AZM reducing IKr, IKs and IK1.Conclusions These data provide an electrophysiological basis for recent FDA guidelines cautioning against combined HCQ/AZM administration for the treatment of Covid-19 on the grounds of potential cardiac safety. We would strongly recommend monitoring of electrocardiographic QT interval with the use of this combination of medications.We explore the cardiac electrophysiological effects of hydroxychloroquine (HCQ) and azithromycin (AZM) alone and in combination, to investigate their safety as a treatment for Covid-19.Using the Comprehensive in-vitro Pro-arrhythmia Assay (CiPA) guidelines, we combine patch clamp studies of individual ion channels, whole heart voltage, Ca2+ and electrocardiographic measurements and human in-silico modelling to directly assess the pro-arrhythmic potential of these drugs.What Are the Clinical Implications?The results provide mechanistic insights for HCQ and its synergistic effects with AZM therapy in terms of QT interval and predisposition to arrhythmia.The translatable cardiac safety assessment associated with clinical HCQ/AZM therapy that emerge may have significant implications for its use in Covid-19 management.Competing Interest StatementThe authors have declared no competing interest.