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Beschreibung

In this difficult period of the SARS-CoV-2 (and its variants) infection responsible for Covid-19 diseases, the importance of scientific works and reviews dealing with these viruses has never been more essential and vital. Reports as of 20th April 2021 indicate over 141 million cases of SARS-CoV-2 infection worldwide (with over 3 million deaths recorded). This volume brings together essential data regarding prevention (vaccination), detection, and various approaches (chemotherapeutic drugs and antibodies) to the potential treatment of coronavirus infections. It presents six chapters concerning the following topics:
(1) the resistance to the spread of SARS-CoV-2 and related Covid-19 diseases within a population based on the pre-existing immunity of a high proportion of individuals as a result infection or previous vaccination
(2) the impact of the Covid-19 pandemic for the South Asian Association for Regional Cooperation (SAARC) region, comprising the Bangladesh, Bhutan, Maldives, Nepal, Pakistan, Sri Lanka, India, and Afghanistan
(3) the effect of candidate drugs chloroquine and hydroxychloroquine on QT interval in infected patients with Covid-19 diseases
(4) the antiviral potential of herbal-based immunomodulators
(5) the humoral immune response in humans based on anti-SARS-CoV-2 antibodies to treat Covid-19 diseases
(6) the various methods and strategies for diagnosing SARS-CoV-2 (and its variants) infection in hosts/humans.

This compilation should prove to be a tool of crucial importance for researchers around the world working on research revolving around coronaviruses, as well as for clinicians confronted by a growing number of patients with COVID-19.

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Veröffentlichungsjahr: 2021

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Table of Contents
BENTHAM SCIENCE PUBLISHERS LTD.
End User License Agreement (for non-institutional, personal use)
Usage Rules:
Disclaimer:
Limitation of Liability:
General:
PREFACE
List of Contributors
Effect of Chloroquine and Hydroxychloroquine on the QT Interval in Patients with COVID-19: A Systematic Review
Abstract
INTRODUCTION
Pharmacodynamics and Pharmacokinetics of Chloroquine and Hydroxychloroquine
Effect of Chloroquine and Hydroxychloroquine Against SARS-CoV-2
In vitro Studies
In vivo Studies
Effect on the QT Interval
Effect on the QT Interval in Patients with COVID-19
CONCLUSION
CONSENT FOR PUBLICATION
CONFLICT OF INTEREST
ACKNOWLEDGEMENTS
REFERENCES
COVID-19: Impact of Pandemic on SAARC Nations
Abstract
INTRODUCTION
STATISTICAL ANALYSIS
SAARC RESPONSE AGAINST COVID-19
MEDICATIONS AND VACCINES DEVELOPMENT
Sepsivac
AYUSH-64 and other Ayurveda Medicines
Mycobacterium w (MW) Vaccine
Convalescent Plasma Therapy
COVID-19: EFFECT ON SAARC ECONOMY
COVID-19: IMPACT ON SAARC ENVIRONMENT
COVID-19: EFFECT ON EDUCATION SECTOR
FUTURE COURSE OF ACTION
CONCLUSION
CONSENT FOR PUBLICATION
CONFLICT OF INTEREST
ACKNOWLEDGEMENTS
REFERENCES
Neutralizing Antibody-Based Therapies against COVID-19
Abstract
INTRODUCTION
Convalescent Plasma Therapy
Monoclonal Antibody Treatment for COVID-19
Egg Yolk Antibodies (IgY) Against SARS-CoV-2
Camelid Antibodies Against SARS-CoV-2
CONCLUDING REMARKS
CONSENT FOR PUBLICATION
CONFLICT OF INTEREST
ACKNOWLEDGEMENTS
REFERENCES
Antiviral Potential of Immunomodulators Based Medicinal Plants against Novel Coronavirus-19: Against the Pandemic
Abstract
INTRODUCTION
MATERIAL AND METHODS
A GENERAL OVERVIEW ON THE NOVEL CORONA VIRUS-2019 AND ITS STRUCTURE
IMMUNSYSTEM AND IMMONOMODULATORS
CONCEPT OF RASAYANA AND RELATIONSHIP BETWEEN HERBAL IMMUNOMODULATORS WITH AYURVEDA FOR COVID19 TREATMENT, A POSSIBLE ROUTE
ALKALOIDS
GLYCOSIDES
FLAVONOIDS
SAPOGENINS
CURCUMIN
CONCLUSION
CONSENT FOR PUBLICATION
CONFLICT OF INTEREST
ACKNOWLEDGEMENTS
AUTHORS CONTRIBUTION
REFERENCES
Diagnostic Measures for COVID-19: Current Status and Advances
Abstract
INTRODUCTION
NEED FOR RELIABLE DIAGNOSTIC TOOLS
DIAGNOSTIC METHODS FOR COVID-19
Molecular Assays for Diagnosis of COVID-19
CDC Influenza SARS-CoV-2 Multiplex Assay
CDC 2019-nCoV RT-PCR Diagnostic Panel
Enzyme-Linked Immunosorbent Assay (ELISA)
Antigen Testing
DNA Sequencing
NATIONAL AND INTERNATIONAL POLICIES ON COVID-19 TESTING
ISSUES AND CHALLENGES IN DIAGNOSIS OF COVID-19
ADVANCEMENTS IN DIAGNOSTIC TOOLS FOR COVID-19
PATENT SCENARIO OF COVID-19 DIAGNOSTICS
CONCLUSION
CONSENT FOR PUBLICATION
CONFLICT OF INTEREST
ACKNOWLEDGEMENTS
LIST OF ABBREVIATIONS
REFERENCES
Herd Immunity: An Indirect Protection Against COVID-19
Abstract
INTRODUCTION
HERD IMMUNITY
PRINCIPLE OF HERD IMMUNITY
DEVELOPING HERD IMMUNITY
COVID-19
COVID 19 AND HERD IMMUNITY
CONCLUSION
CONSENT FOR PUBLICATION
CONFLICT OF INTEREST
ACKNOWLEDGEMENTS
REFERENCES
Coronaviruses
(Volume 1)
Edited by
Jean-Marc Sabatier
Institute of NeuroPhysiopathology
Marseille, Cedex
France

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PREFACE

In this difficult period of the SARS-CoV-2 (and its variants) infection responsible for Covid-19 diseases, the importance of scientific works and reviews dealing with these viruses has never been more essential and vital. This book brings together essential data regarding prevention (vaccination), detection, and various approaches (chemotherapeutic drugs and antibodies) to the potential treatment of coronavirus infections. It consists of six chapters concerning, (1) the effect of candidate drugs chloroquine and hydroxychloroquine on QT interval in infected patients with Covid-19 diseases (chapter 1 by Aleem et al.), (2) the impact of the Covid-19 pandemic for the South Asian Association for Regional Cooperation (SAARC), comprising the Bangladesh, Bhutan, Maldives, Nepal, Pakistan, Sri Lanka, India, and Afghanistan (Chapter 2 by Kanwar et al.), (3) the humoral immune response in humans based on anti-SARS-CoV-2 antibodies to treat Covid-19 diseases (chapter 3 by Çalık1 et al.), (4) the antiviral potential of herbal-based immunomodulators (chapter 4 by Kumari et al.), (5) the various methods and strategies for diagnosing SARS-CoV-2 (and its variants) infection in hosts/humans (Chapter 5 by Narvekar et al.), and (6) the resistance to the spread of SARS-CoV-2 and related Covid-19 diseases within a population based on the pre-existing immunity of a high proportion of individuals as a result infection or previous vaccination (chapter 6 by Tiwari & Sahu). Such a book comprising a compilation of key data on SARS-CoV-2 and Covid-19 should certainly be a tool of crucial importance for researchers around the world working on these research themes, as well as for clinicians confronted to a growing number of patients with Covid-19 (data from 20th April 2021: 141 million cases of SARS-CoV-2 infection worldwide, with over 3 million deaths).

Jean-Marc Sabatier Institute of NeuroPhysiopathology Marseille, Cedex France

List of Contributors

Aleem Abdul, Internal MedicineLehigh Valley HospitalAllentown, PAUSANarvekar Aditya, Department of Pharmaceutical Sciences and TechnologyInstitute of Chemical TechnologyMumbai-400019IndiaChaudhari Ameya, Department of Biomedical EngineeringDuke UniversityDurham, North Carolina-27708USAKumar Amit, Department of Chemistry and Center of Advanced Studies in ChemistryPanjab UniversityChandigarh, U.T.-160014IndiaVenaik Anita, Department of General ManagementAmity Business SchoolAmity University Noida Uttar Pradesh– 201313IndiaMutlu Betül, Yıldız Technical UniversityFaculty of Chemical and Metallurgical Engineering, Department of BioengineeringIstanbulTurkeyMishra Bhargawi, Department of NeurologyInstitute of Medical SciencesBanaras Hindu University Uttar Pradesh-221001IndiaVithlani Darsh, Department of Dyestuff TechnologyInstitute of Chemical TechnologyMumbai-400019IndiaKellison Erik, CardiologyCHI Franciscan Heart and Vascular AssociatesTacoma, WAUSAMahadevaiah Guruprasad, CardiologyCalifornia North State University College of MedicineSacramento, CAUSAAy Hatice Feyzan, Yıldız Technical UniversityFaculty of Chemical and Metallurgical Engineering, Department of BioengineeringIstanbulTurkeyÇalık Hilal, Yıldız Technical UniversityFaculty of Chemical and Metallurgical Engineering, Department of BioengineeringIstanbulTurkeyRathee Jyoti, Department of Chemistry and Center of Advanced Studies in ChemistryPanjab UniversityChandigarh, U.T.-160014IndiaShariff Nasir, CardiologyCHI Franciscan Heart and Vascular AssociatesTacoma, WAUSAMehta Neena, Department of BiochemistryRayat Bahra Dental College and HospitalMohali, PunjabIndiaTiwari Prashant, School of PharmacyArka Jain University, JamshedpurJharkhandIndiaSahu Pratap Kumar, School of Pharmaceutical SciencesSiksha O Anusandhan Deemed to be UniversityBhuba-neswar, Odisha, 751029IndiaDandekar Prajakta, Department of Pharmaceutical Sciences and TechnologyInstitute of Chemical TechnologyMumbai-400019IndiaÇakır-Koç Rabia, Yıldız Technical UniversityFaculty of Chemical and Metallurgical Engineering, Department of BioengineeringIstanbulTurkeyHealth Institutes of Turkey (TUSEB)Turkey Biotechnology InstituteIstanbulTurkeyYılmaz Rabia, Yıldız Technical UniversityFaculty of Chemical and Metallurgical Engineering, Department of BioengineeringIstanbulTurkeyJain Ratnesh, Department of Chemical EngineeringInstitute of Chemical TechnologyMumbai-400019IndiaKumari Rinki, Department of MicrobiologyHind Institute of Medical Sciences, MauAtaria, Sitapur Rd, Uttar Pradesh-261303IndiaKanwar Rohini, Department of Chemistry and Center of Advanced Studies in ChemistryPanjab UniversityChandigarh, U.T.-160014IndiaChikkabyrappa Sathish, CardiologySeattle Children's Hospital, University of Washington School of MedicineSeattle,WAUSAMehta S.K., Department of Chemistry and Center of Advanced Studies in ChemistryPanjab UniversityChandigarh, U.T.-160014IndiaRai Snehalata, School of Biomedical EngineeringIndian Institute of Technology (Banaras Hindu University)Varanasi-221005, Uttar PradeshIndia

Effect of Chloroquine and Hydroxychloroquine on the QT Interval in Patients with COVID-19: A Systematic Review

Abdul Aleem1,*,Guruprasad Mahadevaiah2,Sathish Chikkabyrappa3,Erik Kellison4,Nasir Shariff 4
1 Internal Medicine, Lehigh Valley Hospital, Allentown, PA, USA
2 Cardiology, California North State University College of Medicine, Sacramento, CA, USA
3 Cardiology, Seattle Children's Hospital, University of Washington School of Medicine, Seattle, WA, USA
4 Cardiology, CHI Franciscan Heart and Vascular Associates, Tacoma, WA, USA

Abstract

Coronavirus disease 2019 (COVID-19) has been a major global health crisis since the influenza pandemic of 1918. Based on data from in vitro studies, traditional antimalarial agents, chloroquine and hydroxychloroquine, have been proposed as potential treatment options for patients with COVID-19. Both these medications have also been noted to prolong the QT interval, which increases the risk of drug-induced torsade de pointes (TdP) or sudden cardiac death (SCD) when used in non-COVID-19 patients. We reviewed the published clinical studies evaluating the QT interval in COVID-19 patients treated with chloroquine/hydroxychloroquine with or without azithromycin. A literature search using Google Scholar, and PubMed was done for studies published from December 2019 to September 2020. Studies with no specific description of the QT interval were excluded from this review. We identified twelve studies that qualified our criteria, which included 2595 patients. This review addresses the pathophysiology of QT prolongation and the incidence of the magnitude of QT prolongation associated with these medications when used in the treatment of patients admitted with COVID-19. Although most incidences of QT prolongation occurred two or more days after the initiation of these medications, early events of QT prolongation on the first day of therapy have also been reported. Notably, the combination of chloroquine/hydroxychloroquine with azithromycin was associated with a higher incidence of QT prolongation. Although QT prolongation is evident in all the described studies, none of these studies were designed to address the risk of QT prolongation associated with these medications in the outpatient setting or when used as prophylaxis against COVID-19. With the currently available literature, caution with close monitoring of the QT interval is advised when using these antimalarial agents in patients hospitalized with COVID-19 infection.

Keywords: Chloroquine, Coronavirus disease 2019, Covid-19, Drug-induced torsade de pointes (tdp), Hydroxychloroquine, Hydroxychloroquine and azithromycin, Qt prolongation, QTc prolongation, SARS-CoV-2, Sudden cardiac death.
*Corresponding author Abdul Aleem: Internal Medicine, Lehigh Valley Hospital, Allentown, PA, USA; Tel: 610-402-1415; E-mail: [email protected]

INTRODUCTION

COVID-19 caused by a beta coronavirus is included in the same subgenus as the severe acute respiratory syndrome (SARS-CoV) virus. Since the cases of an acute respiratory illness caused by the COVID-19 were initially reported in China in December 2019, the viral infection has spread worldwide, with about four million confirmed cases and more than three hundred thousand death [1]. There has been an urgency to mitigate this illness with experimental therapies and drug repurposing. Currently, there are over 25 potential drugs that are being investigated, with ten in active clinical trials [2]. Traditional antimalarial agents, chloroquine and hydroxychloroquine, have been suggested as potential treatment options for patients with COVID-19 infection based on their in vitro activity against the virus [3]. During the early course of the pandemic, the US Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA), allowing the use of chloroquine and hydroxychloroquine in adult hospitalized patients with COVID-19 outside of a clinical trial . The issuance of the EUA has enabled the conduct of randomized controlled trials(RCTs) to test for the efficacy and safety of these medications [4]. In this systematic review, we aimed to discuss the latest available data regarding the specific complication of QT prolongation associated with the use of chloroquine and hydroxychloroquine in patients with COVID-19 infection.

Pharmacodynamics and Pharmacokinetics of Chloroquine and Hydroxychloroquine

Chloroquine is a 9-aminoquinoline that was first synthesized in 1934 from its parent compound quinine, which was derived from the bark of the tropical cinchona tree [5]. Hydroxychloroquine (HCQ) belongs to the same molecular family as chloroquine and differs from its counterpart by the presence of a hydroxyl group [5, 6]. Historically, chloroquine and hydroxychloroquine have been used as antimalarial agents for decades. With the noted immunomodulatory properties of these medications, they have been used widely for the treatment of chronic systemic inflammatory diseases like rheumatoid arthritis and systemic lupus erythematosus [5]. The pharmacokinetics of hydroxychloroquine is similar to that of chloroquine; however, hydroxychloroquine is reported to be less toxic than chloroquine [5]. Both chloroquine and hydroxychloroquine have excellent oral absorption, bioavailability, low blood clearance and, very long half-lives (40 days and 50 days) and are eliminated by hepatic as well as renal excretion [7-9].

The antiviral properties of chloroquine have been explored as early as 1987 [10]. In-vitro studies have demonstrated the effectiveness of these medications on different RNA viruses, including human immunodeficiency virus (HIV) [6, 11]. However, in vitro success of these drugs has not been replicated in clinical trials [6, 12]. In vitro studies have shown hydroxychloroquine to inhibit SARS-CoV-2 replication with a 50% maximal effective concentration (EC50) [13]. They are also known to block virus infection by increasing the endosomal pH and interfering with glycosylation of cellular receptors of SARS-CoV [12]. Chloroquine and hydroxychloroquine demonstrate their anti-inflammatory properties by blocking the secretion of pro-inflammatory cytokines such as IFN-gamma, TNF-α, IL-6, and IL-1 [5]. This anti-inflammatory action of chloroquine and hydroxychloroquine has been hypothesized to be beneficial in countering the inappropriate immune activation by SARS-CoV-2, leading to ARDS [14].

Effect of Chloroquine and Hydroxychloroquine Against SARS-CoV-2

In vitro Studies

Based on previous preclinical data demonstrating hydroxychloroquine having anti-SARS-CoV activity in the last SARS outbreak [15], Yao et al. studied the activity of chloroquine and hydroxychloroquine in vitro against SARS-CoV-2. Hydroxychloroquine was noted to be more effective than chloroquine in vitro against SARS-CoV-2 infection [3]. Liu et al. also described the positive effect of chloroquine and hydroxychloroquine on SARS-CoV-2 in vitro and concluded hydroxychloroquine to be superior to chloroquine in inhibiting SARS-CoV-2 in vitro. Chloroquine was associated with a significant reduction in quantitative real-time ET-PCR viral load in Vero E6 cells infected with SARS-CoV [13]. Chloroquine was also noted to inhibit the entry and post-entry stages of the SARS-CoV virus at fluid concentrations, which could be achieved at doses usually used in patients with rheumatoid arthritis [9, 16].

In vivo Studies

Data from several initial nonrandomized control studies showed significant improvement in clinical symptoms and early viral conversion rates with the use of hydroxychloroquine and chloroquine in patients with COVID-19 [17-20]. These studies, however, did not address the cardiac adverse effects of these medications, precisely their effect on QT interval by these medications. Data from further observational studies examining the clinical efficacy of these drugs could not replicate the positive results demonstrated by the initial trials [21-23]. A double-masked randomized control trial by Borba et al. in Brazil involving 81 severely ill patients who were randomized to receive a high and low dosage of chloroquine, which was given concurrently with azithromycin and oseltamivir, was abruptly halted due to the high mortality rate noted during the study which was 39% in the top dosage group and 15% in the low dosage group, respectively [24]. There was an observed association of the use of these medications with QT prolongation and poor outcomes [23, 24].

Effect on the QT Interval

Ventricular repolarization duration and the QT interval are determined by the ventricular action potential [25]. In contrast to the QRS duration, the QT interval varies with heart rate and autonomic tone. The outward potassium currents occur due to the two delayed rectifying channels, - IKr (rapid) and IKs (slow) channels. The inhibition or reduction of the IKr channel activity is the primary cause of prolongation of the QT interval. Secondary to the reduced IKr channel activity, some L-type calcium channels (which are inactive during depolarization) may become activated, resulting in early afterdepolarization, which in turn results in triggered arrhythmia facilitating polymorphic ventricular tachycardia. Any change or defect in the function of ion channels and related proteins of the ventricular myocytes leads to abnormal repolarization of the ventricular myocardium, which results in the prolongation of the QT interval on the electrocardiogram (ECG) [26]. These defects can be congenital, drug-induced, or due to electrolyte abnormalities. Several medications that include macrolides, fluoroquinolones, antipsychotics, and antiarrhythmic drugs that block potassium channels are known to prolong the QT interval. Amongst the different classes of antimalarial medications, quinolines, and structurally related antimalarial drugs like chloroquine and hydroxychloroquine have clinically substantial cardiovascular effects [27]. Chloroquine and hydroxychloroquine are known to cause prolongation of QT interval by inhibiting the rapidly activating delayed rectifier K+ current (IKr) encoded by a cardiac potassium channel gene called the human-ether-a-go-go-related gene (hERG). This blockade causes a decrease in the net repolarizing current leading to an increase in the duration of ventricular action potential manifesting as a prolonged QT interval, which can potentially cause life-threatening ventricular arrhythmias like torsades de pointes or sudden cardiac death (SCD) [26, 28, 29].

Effect on the QT Interval in Patients with COVID-19

Chloroquine and hydroxychloroquine have been demonstrated to cause prolongation of the QT interval when used to manage patients with malaria and rheumatoid arthritis [30]. There are also several case reports of polymorphic ventricular tachycardia in non-COVID-19 patients receiving these medications [31, 32]. The first randomized control trial (Table 1) evaluating the clinical efficacy and safety of chloroquine in patients with severe COVID-19 was published by Borba et al. [24]. In this prospective study evaluating the safety and clinical efficacy chloroquine, 81 patients with severe COVID-19 illness were randomized into two groups to receive either high dosage chloroquine (600mg twice daily for ten days) or low dosage chloroquine (450mg twice a day for the first day followed by once a day for four days). All patients received ceftriaxone and azithromycin as well. There were significantly higher events of QT prolongation in the higher dose group compared to the lower dose group (18.9% vs. 11.1%). Two patients in the high dosage arm developed ventricular tachycardia prior to their death. The study was terminated early due to its high mortality rate in the high dosage group compared to the low dosage group [24].

Table 1Summary of the published prospective/retrospective studies describing the effect of chloroquine and/or hydroxychloroquine in combination with or without azithromycin on QT interval in patients hospitalized with COVID-19 illness.AuthorStudy DesignObjectiveSample Size(N)Baseline QTc Interval(ms)Effect on QT IntervalResultsBorbaet al. [24]Double masked randomized control trialEvaluate the safety and efficacy of high dosage chloroquine (600mg twice daily for 10 days) and low dosage chloroquine (450mg twice a day for the first day followed by once a day for 4 days) in hospitalized patients with severe COVID- 19 infectionN=81 High dosage group:40 Low dosage group:41High dosage group: 421.9 ± 24.0Low dosage group: 427.8 ± 31.0QTc interval (>500 ms) noted in 7 patients (18.9%) in the high dosage group compared with 4 patients (11.1%) in the low-dosage groupStudy was terminated due to trends towards a higher lethality rate of 39% in the high dosage group and 15% in the low dosage group. Ventricular arrhythmia developed in 2/37 patients of the high dose chloroquine arm and 0/28 in the low dose armRosenberget al. [22]Retrospective multicenter cohort studyEvaluate mortality in hospitalized patients receiving HCQ, AZ, both or neitherN=1438HCQ plus AZ: (735)HCQ alone: (271)AZ alone: (211)Neither drug: (221)Not specifiedHCQ plus AZ:12.6% (80 patients)HCQ alone:16.7% (39 patients)AZ alone:8.3% (15 patients) Neither drug:8.4%Compared to patients receiving neither HCQ or AZ, higher mortality was noted in patients receiving these medications: HCQ alone (HR, 1.08) combination HCQ with AZ (HR, 1.35) AZ alone (HR, 0.56) Adjusted cardiac arrest events were significantly higher in patients receiving a combination of AZ and HCQ when compared to patients receiving neither of the medications (HR 2.97)Mercuroet al. [33]Retrospective single center studyAssess the QT prolongation in patients receiving HCQ with or without concomitant AZN=90Concomitant AZ with HCQ: (53)HCQ alone: (37)Overall:455 (430-474) msHCQ: 473 (454-487) msHCQ and AZ: 442 (427-461) ms10 of 90 patients (11%) had ΔQTc of 60 ms or more; 18 (20%) had post treatment QTc intervals of 500 ms or more.HCQ monotherapy: 7 (19%) developed QTc > 500 ms and 3 (3%) had ΔQTc > 60 msConcomitant AZ: 11 (21%) had QTc > 500ms and 7 (13%) had a ΔQTc > 60 msHigh risk of QT prolongation was noted in patients receiving HCQ 1 patient on HCQ developed Torsades de PointesBessièreet al. [34]Prospective single center case series studyExamine the effect and safety of HCQ with or without AZ on QT interval in ICU patientsN=40HCQ alone: (22)In association with AZ: (18)414 (392-428) ms93% of the patients showed an increase in QTc after receiving HCQ with or without AZ. QTc > 500ms in 6 patients (33%) receiving HCQ with AZ and 1 patient (5%) receiving HCQ alone 10 patients with Δ QTc >60 ms Total patients with prolonged QTc -14High incidence of QT prolongation in patients receiving HCQSalehet al. [35]Prospective observational studyExamine the effect of Chloroquine, HCQ and AZ on the QTc interval in hospitalized patients with COVID-19Monotherapy group:201 chloroquine (10) HCQ: 191)Combination group: (chloroquine/HCQ and AZ):119Monotherapy group: 440.6 ± 24.9Combination group: 439.9 ± 24.7Maximum QTc was significantly longer in the combination group 470.4 ± 45.0 ms vs. 453.3 ± 37.0 in the monotherapy groupQTC >500 ms: 7 patients in monotherapy vs. 11 patients in combination therapyNo instances of TdP or arrhythmogenic death QT prolongation was noted after day 1 of treatment 7 patients (2 on monotherapy) required discontinuation of these medications due to QTc prolongation 7 Patients-non sustained monomorphic ventricular tachycardia 1 patient had sustained monomorphic tachycardia in the setting of viral myocarditis 17 patients developed new onset atrial fibrillationChorinet al. [36]Retrospective multicenter studyAssess the progression of QTc and incidence of arrhythmia and mortality in patients treated with HCQ/AZN=251QTc:439 ±29 ms (QT interval assessed at baseline and up to 3 days of completion of therapy)58 /251 (23%) patients treated with HCQ/AZ developed extreme new QTc prolongation of > 500 ms. The QTc interval prolonged from 439 ± 29 ms at baseline to 473 ± 36 ms (P < .001) with therapy.The combination of HCQ/AZ significantly prolonged the QTc predisposing to life threatening arrhythmia Maximum QT prolongation was noted 4 ± 2 days of therapy. One patient developed polymorphic ventricular tachycardia requiring defibrillationRamireddyet al. [37]Retrospective single center studyExamine the effect of HCQ, AZ or both on the QTc IntervalN=98AZ:27HCQ:10Combination (AZ/HCQ): 61448±29 msOverall QTc increased to 459±36ms (p=0.005) with drug administration with the highest mean change in QTc values in the combined HCQ and AZ group 12% of patients reached critical QTc prolongationQTc prolongation was several folds higher with combination therapy compared to AZ alone (17±39 ms versus 0.5±40 ms; p=0.07).Mahevaset al. [38]Retrospective cohort studyAssess effectiveness of HCQ in admitted patients on oxygen (non-ICU)N=181HCQ: (84)Control: 89Not specified7/84 had QTc increase > 60 ms, of which one had QTc> 500 msAt day 21, overall survival was 89% in treated vs. 91% in the control group Rate of survival was 69% in treated vs. 74% in control on day 21Perinelet al [39]Prospective single center cohort studyEvaluate the pharmacokinetic properties of HCQ (200 mg TID PO) in ICU COVID 19 patientsN=13Not specifiedDosage of HCQ needed to be reduced in 4 patients (200 mg of HCQ twice daily) due to increased levels of HCQ on blood samples. Two patients needed withdrawal of the medication due to QT interval prolongation (381 to 510 ms and 432 to 550 ms) on day 2 and 3, respectivelyOnly 8/13 patients achieved the minimum therapeutic level of 1 mg/ml. QT prolongation noted on day 2 and day 3 of treatment in 2/13 patientsMolinaet al. [40]Prospective single center studyStudy the virologic and clinical outcomes of treatment with HCQ and AZN=11Not specifiedOne patient was noted to have QT interval prolongation from 405 ms to 460 and 470 ms requiring discontinuation of therapyRepeat nasopharyngeal swabs were positive in 8 of the 10 patients at 5 daysVoisinet al. [41]Prospective single center studyExamine the effect of HCQ and AZ on the QTc Interval by analysing serial ECGs recorded in patients hospitalized with COVID-19 pneumonia and treated with both HCQ and AZN=50QTc:408 ms at baseline (IQR, 343-478 ms) (QT interval assessed at base and at day 3, at day 5 and at discharge)Mean QTc interval increased up to 437 ms (IQR, 380-500 ms) at day 3 and to 456 ms (IQR, 397-518 ms) at day 5 Median QTc interval at day 0, day 3, and day 5 was 403, 430, and 460 ms, respectively 38 patients (76%) had short-term modifications of the QTc duration (>30 ms) 6 patients (12%) had treatment discontinuationThe combination of HCQ and AZ used in short duration significantly prolong the QTc interval necessitating cardiac monitoring at regular intervalsCiprianiet al. [42]Prospective single center studyExamine the effect of HCQ and AZ on the QTc interval with 12 lead 24-hour Holter monitoring in patients hospitalized with COVID-19 pneumoniaN=22QTc:426 ms at baseline (IQR, 403-447 ms)QTc interval increased up to 450 ms (IQR, 416-476 ms) 4 patients had QTc ≥ 480msTherapy with HCQ and AZ prolongs the QTc interval. Multiple daily ECG is not recommended due to stability in the QTc duration
Abbreviations: QTc, corrected QT; HCQ, Hydroxychloroquine; ms, milliseconds; AZ, Azithromycin; TdP, torsades de Pointes; ΔQTc, change in corrected QT interval; IQR, Interquartile range; ECG, Electro-cardiogram;

In a large retrospective multicenter observational cohort study of 1438 patients admitted with COVID-19, the adjusted hazard ratio for in-hospital mortality for treatment with hydroxychloroquine alone was 1.08 and when combined with azithromycin was 1.35 when compared to patients receiving neither of these medications. The combination of azithromycin with hydroxychloroquine was associated with higher events of cardiac arrests as compared to patients receiving neither of these medications (15.5% vs. 6.8%). QTc prolongation was noted in 12.6% receiving azithromycin with hydroxychloroquine, 16.7% in patients receiving hydroxychloroquine, and 8.4% receiving neither of the medications [22].

Mercuro et al. reported a change in QT interval in a cohort of 90 hospitalized patients who had received hydroxychloroquine with or without azithromycin [33]. The median baseline QTc was 455 (430-474) msec. Patients receiving the combination of hydroxychloroquine and azithromycin had a more considerable increase in QT interval (23 {10-40} msec) compared with those receiving hydroxychloroquine alone (5.5 {−15.5 to 34.25} [1] msec) (p=0.03) Of the 53 receiving combined therapy, 11 (13%) had prolonged QTc over 500 msec, and 7 (13%) had a change in QTc of 60 msec or more. One patient on combination therapy developed QT prolongation (499 msec) and torsades de pointes three days later. In a single-center French study of 40 patients admitted to intensive care unit receiving hydroxychloroquine (200mg twice a day for ten days) of which 45% of patients also received azithromycin reported that 93% of patients showed an increase in QTc with seven patients (18%) having QTc interval over 500msec [34]. The prolongation of the QT interval was noted after 3 to 5 days of being on therapy.

Another prospective observational study examined the effect of chloroquine, hydroxychloroquine, and azithromycin on QTc interval in 201 patients hospitalized with COVID-19, in which ten patients received chloroquine while 191 patients received hydroxychloroquine [35]. In patients receiving a combination of hydroxychloroquine/chloroquine with azithromycin, the QT prolongation was significantly longer than patients receiving hydroxychlo- roquine/chloroquine without azithromycin (470±45 msec versus 453 ±37 msec, P=0.004). Seven patients (3.5%) required discontinuation of the medications due to the significant prolongation of the QT intervals. There were no reported instances of TdP