Mechanistic insights into ventricular arrhythmogenesis of hydroxychloroquine and azithromycin for the treatment of COVID-19

Abstract

Background and Purpose: We investigate mechanisms for potential pro-arrhythmic effects of hydroxychloroquine (HCQ) alone, or combined with azithromycin (AZM), in Covid-19 management supplementing the limited available experimental cardiac safety data. Experimental Approach: We integrated patch-clamp studies utilizing In Vitro ProArrhythmia Assay Schema IC50 paradigms, molecular modelling, cardiac multi-electrode array and voltage (RH237) mapping, ECG studies, and Ca2+ (Rhod-2 AM) mapping in isolated Langendorff-perfused guinea-pig hearts with human in-silico ion current modelling. Key Results: HCQ blocked IKr and IK1 with IC50s (10±0.6 and 34±5.0 μM) within clinical therapeutic ranges, INa and ICaL at higher IC50s, leaving Ito and IKs unaffected. AZM produced minor inhibition of INa, ICaL, IKs, and IKr,, sparing IK1 and Ito. HCQ+AZM combined inhibited IKr and IK1 with IC50s of 7.7±0.8 μM and 30.4±3.0 μM, sparing INa, ICaL and Ito. Molecular modelling confirmed potential HCQ binding to hERG. HCQ slowed heart rate and ventricular conduction. It prolonged PR, QRS and QT intervals, and caused prolonged, more heterogeneous, action potential durations and intracellular Ca2+ transients. These effects were accentuated with combined HCQ+AZM treatment, which then elicited electrical alternans, re-entrant circuits and wave break. Modelling studies attributed these to integrated HCQ and AZM actions reducing IKr and IK1, thence altering cell Ca2+ homeostasis. Conclusion and implications: Combined HCQ+AZM treatment exerts pro-arrhythmic ventricular events by synergetically inhibiting IKr, IKs with resulting effects on cellular Ca2+ signalling, and action potential propagation and duration. These findings provide an electrophysiological basis for recent FDA cardiac safety guidelines cautioning against combining HCQ/AZM when treating Covid-19.

Effects of Hydroxychloroquine and Azithromycin on iPSC-derived Cardiomyocytes: Considerations for the Treatment of COVID-19 Patients

“…Besides the reduced cell viability, treatment with 10 µM HCQ resulted in a progressive increase in FPDc, CV and beating frequency in iPSC-CMs during the 7-day treatment. The increased FPDc was also reported in the guinea pig heart upon acute treatment with 10 µM HCQ alone ex vivo 16 . In our study, we observed a slight reduction of FPDc in iPSC-CMs after the 7-day treatment with 10 µM AZM alone, while CV was increased to a similar extend as in cells treated with 10 µM HCQ.…”

“…As MEA-measurements and video-based motion analysis allow frequent documentation of iPSC-CM function during 7 days of drug treatment, our study provides first evidence for the functional consequences of AZM and HCQ under long-term treatment, whereas insights from previous studies are limited to acute or short-term treatment 16 . We show that both AZM and HCQ negatively affect the viability, morphology, sarcomeric structure as well as the contractile and electrophysiological function of iPSC-CMs at clinically relevant concentrations and treatment duration.…”

“…A retrospective multicenter study by Rosenberg et al confirmed that the combination therapy of HCQ and AZM not only potentiated the risk for cardiac arrest, but is further associated with an increased mortality rate 15 . In line with these findings, Wang et al showed that the treatment with combined HCQ and AZM, but not HCQ or AZM alone, enhanced the susceptibility for ventricular arrhythmias 16 . QT interval prolongation, as reported by various groups 17,18,19,20 , must be considered as an additional adverse effect for COVID-19 patients resulting from the HCQ and AZM combination therapy.…”

“…Based on our results, we assume that the HCQ-induced increase in CV and alteration in contraction may be caused by enhanced expression (or accumulation) of Cx43 and altered gating properties of the sodium channel 37 . Acute treatment with HCQ was reported to have an effect on I Na with an IC 50 of 113.9 ± 78.3 µM, which may explain the reduction in the electrical signal transmission observed in the guinea pig heart treated with 10 µM HCQ ex vivo 16 . In our study, we observed no effect of 10 µM HCQ on I Na after the 7-day treatment, but altered gating properties.…”

Chloroquine and hydroxychloroquine for COVID‐19: Perspectives on their failure in repurposing

“…Hydroxychloroquine, and to a lesser extent AZM, blocks the IKr current and their combination has a greater effect 57 . In addition, AZM also increases peak and late sodium current, thereby further delaying cardiac repolarization 58 .…”