1
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Abudan AA, Vaidya VR, Tripathi B, Noseworthy PA, DeSimone DC, Egbe A, Arora S, Sridhar H, DeSimone CV, Mulpuru S, Deshmukh AJ. Burden of arrhythmia in hospitalized HIV patients. Clin Cardiol 2020; 44:66-77. [PMID: 33295667 PMCID: PMC7803370 DOI: 10.1002/clc.23506] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 10/19/2020] [Accepted: 10/29/2020] [Indexed: 02/02/2023] Open
Abstract
Background The improved life expectancy observed in patients living with human immunodeficiency virus (HIV) infection has made age‐related cardiovascular complications, including arrhythmias, a growing health concern. Hypothesis We describe the temporal trends in frequency of various arrhythmias and assess impact of arrhythmias on hospitalized HIV patients using the Nationwide Inpatient Sample (NIS). Methods Data on HIV‐related hospitalizations from 2005 to 2014 were obtained from the NIS database using International Classification of Diseases, 9th Revision (ICD‐9) codes. Data was further subclassified into hospitalizations with associated arrhythmias and those without. Baseline demographics and comorbidities were determined. Outcomes including in‐hospital mortality, cost of care, and length of stay were extracted. SAS 9.4 (SAS Institute Inc., Cary, NC) was utilized for analysis. A multivariable analysis was performed to identify predictors of arrhythmias among hospitalized HIV patients. Results Among 2 370 751 HIV‐related hospitalizations identified, the overall frequency of any arrhythmia was 3.01%. Atrial fibrillation (AF) was the most frequent arrhythmia (2110 per 100 000). The overall frequency of arrhythmias increased over time by 108%, primarily due to a 132% increase in AF. Arrhythmias are more frequent among older males, lowest income quartile, and nonelective admissions. Patients with arrhythmias had a higher in‐hospital mortality rate (9.6%). In‐hospital mortality among patients with arrhythmias decreased over time by 43.8%. The cost of care and length of stay associated with arrhythmia‐related hospitalizations were mostly unchanged. Conclusions Arrhythmias are associated with significant morbidity and mortality in hospitalized HIV patients. AF is the most frequent arrhythmia in hospitalized HIV patients.
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Affiliation(s)
- Anas A Abudan
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, United States.,Department of Internal Medicine, University of Kansas School of Medicine, Kansas City, Kansas, United States
| | - Vaibhav R Vaidya
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, United States
| | - Byomesh Tripathi
- Department of Medicine, Mount Sinai St Luke's-Roosevelt Hospital, New York, New York, United States
| | - Peter A Noseworthy
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, United States
| | - Daniel C DeSimone
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, United States.,Division of Infectious Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - Alexander Egbe
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, United States
| | - Shilpkumar Arora
- Department of Medicine, Mount Sinai St Luke's-Roosevelt Hospital, New York, New York, United States
| | - Haarini Sridhar
- University of California, Berkeley, California, United States
| | | | - Siva Mulpuru
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, United States
| | - Abhishek J Deshmukh
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, United States
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2
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Hazim A, Belhamadia Y, Dubljevic S. A Simulation Study of the Role of Mechanical Stretch in Arrhythmogenesis during Cardiac Alternans. Biophys J 2020; 120:109-121. [PMID: 33248131 PMCID: PMC7820729 DOI: 10.1016/j.bpj.2020.11.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 11/03/2020] [Accepted: 11/13/2020] [Indexed: 12/20/2022] Open
Abstract
The deformation of the heart tissue due to the contraction can modulate the excitation, a phenomenon referred to as mechanoelectrical feedback (MEF), via stretch-activated channels. The effects of MEF on the electrophysiology at high pacing rates are shown to be proarrhythmic in general. However, more studies need to be done to elucidate the underlying mechanism. In this work, we investigate the effects of MEF on cardiac alternans, which is an alternation in the width of the action potential that typically occurs when the heart is paced at high rates, using a biophysically detailed electromechanical model of cardiac tissue. We observe that the transition from spatially concordant alternans to spatially discordant alternans, which is more arrhythmogenic than concordant alternans, may occur in the presence of MEF and when its strength is sufficiently large. We show that this transition is due to the increase of the dispersion of conduction velocity. In addition, our results also show that the MEF effects, depending on the stretch-activated channels’ conductances and reversal potentials, can result in blocking action potential propagation.
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Affiliation(s)
- Azzam Hazim
- Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada
| | - Youssef Belhamadia
- Department of Mathematics and Statistics, American University of Sharjah, Sharjah, United Arab Emirates
| | - Stevan Dubljevic
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada.
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3
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Żołek T, Qile M, Kaźmierczak P, Bloothooft M, van der Heyden MAG, Maciejewska D. Drug-likeness of linear pentamidine analogues and their impact on the hERG K+channel – correlation with structural features. RSC Adv 2019; 9:38355-38371. [PMID: 35540224 PMCID: PMC9082326 DOI: 10.1039/c9ra08404e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 11/15/2019] [Indexed: 01/08/2023] Open
Abstract
The pentamidines with S atoms or sulfanilide groups in the linker have favorable drug-likeness parameters and low toxicity.
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Affiliation(s)
- Teresa Żołek
- Department of Organic Chemistry
- Faculty of Pharmacy
- Medical University of Warsaw
- 02-097 Warsaw
- Poland
| | - Muge Qile
- Department of Medical Physiology
- Division Heart & Lungs
- University Medical Center Utrecht
- Utrecht
- The Netherlands
| | - Paweł Kaźmierczak
- Department of Organic Chemistry
- Faculty of Pharmacy
- Medical University of Warsaw
- 02-097 Warsaw
- Poland
| | - Meye Bloothooft
- Department of Medical Physiology
- Division Heart & Lungs
- University Medical Center Utrecht
- Utrecht
- The Netherlands
| | - Marcel A. G. van der Heyden
- Department of Medical Physiology
- Division Heart & Lungs
- University Medical Center Utrecht
- Utrecht
- The Netherlands
| | - Dorota Maciejewska
- Department of Organic Chemistry
- Faculty of Pharmacy
- Medical University of Warsaw
- 02-097 Warsaw
- Poland
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4
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Asahi Y, Nomura F, Abe Y, Doi M, Sakakura T, Takasuna K, Yasuda K. Electrophysiological evaluation of pentamidine and 17-AAG in human stem cell-derived cardiomyocytes for safety assessment. Eur J Pharmacol 2019; 842:221-230. [DOI: 10.1016/j.ejphar.2018.10.046] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 10/22/2018] [Accepted: 10/29/2018] [Indexed: 10/28/2022]
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5
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Wang W, Zhang S, Ni H, Garratt CJ, Boyett MR, Hancox JC, Zhang H. Mechanistic insight into spontaneous transition from cellular alternans to arrhythmia-A simulation study. PLoS Comput Biol 2018; 14:e1006594. [PMID: 30500818 PMCID: PMC6291170 DOI: 10.1371/journal.pcbi.1006594] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 12/12/2018] [Accepted: 10/23/2018] [Indexed: 02/01/2023] Open
Abstract
Cardiac electrical alternans (CEA), manifested as T-wave alternans in ECG, is a clinical biomarker for predicting cardiac arrhythmias and sudden death. However, the mechanism underlying the spontaneous transition from CEA to arrhythmias remains incompletely elucidated. In this study, multiscale rabbit ventricular models were used to study the transition and a potential role of INa in perpetuating such a transition. It was shown CEA evolved into either concordant or discordant action potential (AP) conduction alternans in a homogeneous one-dimensional tissue model, depending on tissue AP duration and conduction velocity (CV) restitution properties. Discordant alternans was able to cause conduction failure in the model, which was promoted by impaired sodium channel with either a reduced or increased channel current. In a two-dimensional homogeneous tissue model, a combined effect of rate- and curvature-dependent CV broke-up alternating wavefronts at localised points, facilitating a spontaneous transition from CEA to re-entry. Tissue inhomogeneity or anisotropy further promoted break-up of re-entry, leading to multiple wavelets. Similar observations have also been seen in human atrial cellular and tissue models. In conclusion, our results identify a mechanism by which CEA spontaneously evolves into re-entry without a requirement for premature ventricular complexes or pre-existing tissue heterogeneities, and demonstrated the important pro-arrhythmic role of impaired sodium channel activity. These findings are model-independent and have potential human relevance.
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Affiliation(s)
- Wei Wang
- Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom
| | - Shanzhuo Zhang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Haibo Ni
- Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom
| | - Clifford J. Garratt
- Manchester Heart Centre, Manchester Royal Infirmary, Manchester, United Kingdom
| | - Mark R. Boyett
- Manchester Heart Centre, Manchester Royal Infirmary, Manchester, United Kingdom
| | - Jules C. Hancox
- Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom
- School of Physiology, Pharmacology and Neuroscience, and Cardiovascular Research Laboratories, School of Medical Sciences, University of Bristol, Bristol, United Kingdom
| | - Henggui Zhang
- Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
- Space Institute of Southern China, Shenzhen, China
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6
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Hihara T, Yamazaki K, Taniguchi T, Yoshinaga T, Ito M, Sawada K. Use of Human Embryonic Stem Cell-Derived Cardiomyocyte Clusters to Assess Potential for Chronic Treatment with Compounds to Cause QT Prolongation. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/pp.2014.54044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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7
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Abstract
T-wave alternans, a manifestation of repolarization alternans at the cellular level, is associated with lethal cardiac arrhythmias and sudden cardiac death. At the cellular level, several mechanisms can produce repolarization alternans, including: (1) electrical restitution resulting from collective ion channel recovery, which usually occurs at fast heart rates but can also occur at normal heart rates when action potential is prolonged resulting in a short diastolic interval; (2) the transient outward current, which tends to occur at normal or slow heart rates; (3) the dynamics of early after depolarizations, which tends to occur during bradycardia; and (4) intracellular calcium cycling alternans through its interaction with membrane voltage. In this review, we summarize the cellular mechanisms of alternans arising from these different mechanisms, and discuss their roles in arrhythmogenesis in the setting of cardiac disease.
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Affiliation(s)
- Zhilin Qu
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California, USA.
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8
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Nieminen T, Verrier RL. Usefulness of T-wave alternans in sudden death risk stratification and guiding medical therapy. Ann Noninvasive Electrocardiol 2010; 15:276-88. [PMID: 20645971 PMCID: PMC6932425 DOI: 10.1111/j.1542-474x.2010.00376.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Visible T-wave alternans (TWA), a beat-to-beat alternation in the morphology and amplitude of the ST segment or T wave, has been observed for over a century to occur in association with life-threatening arrhythmias in patients with acute coronary syndrome, heart failure, and cardiac channelopathies. This compelling linkage prompted development of quantitative techniques leading to FDA-cleared commercial methodologies for measuring nonvisible levels of TWA in the frequency and time domains. The first aim of this review is to summarize evidence from more than a hundred studies enrolling a total of >12,000 patients that support the predictivity of TWA for cardiovascular mortality and sudden cardiac death. The second focus is on the usefulness of TWA in guiding therapy. Until recently, TWA has been used primarily in decision making for cardioverter-defibrillator implantation. Its potential utility in guiding pharmacologic therapy has been underappreciated. We review clinical literature supporting the usefulness of TWA as an index of antiarrhythmic effects and proarrhythmia for different drug classes. Beta-adrenergic and sodium channel-blocking agents are the most widely studied drugs in clinical TWA investigations, with both reducing TWA magnitude; the exception is patients in whom sodium channel blockade discloses the Brugada syndrome and provokes macroscopic TWA. An intriguing possibility is that TWA may help to detect beneficial effects of nonantiarrhythmic agents such as the angiotensin II receptor blocker valsartan, which indirectly protects from arrhythmia through improving myocardial remodeling. We conclude that quantitative analysis of TWA has considerable potential to guide pharmacologic intervention and thereby serve as a therapeutic target.
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Affiliation(s)
- Tuomo Nieminen
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
- Department of Pharmacological Sciences, Medical School, University of Tampere, Finland, and Department of Internal Medicine, Päijät‐Häme Central Hospital, Lahti, Finland
| | - Richard L. Verrier
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
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9
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Corrias A, Jie X, Romero L, Bishop MJ, Bernabeu M, Pueyo E, Rodriguez B. Arrhythmic risk biomarkers for the assessment of drug cardiotoxicity: from experiments to computer simulations. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2010; 368:3001-25. [PMID: 20478918 PMCID: PMC2944395 DOI: 10.1098/rsta.2010.0083] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
In this paper, we illustrate how advanced computational modelling and simulation can be used to investigate drug-induced effects on cardiac electrophysiology and on specific biomarkers of pro-arrhythmic risk. To do so, we first perform a thorough literature review of proposed arrhythmic risk biomarkers from the ionic to the electrocardiogram levels. The review highlights the variety of proposed biomarkers, the complexity of the mechanisms of drug-induced pro-arrhythmia and the existence of significant animal species differences in drug-induced effects on cardiac electrophysiology. Predicting drug-induced pro-arrhythmic risk solely using experiments is challenging both preclinically and clinically, as attested by the rise in the cost of releasing new compounds to the market. Computational modelling and simulation has significantly contributed to the understanding of cardiac electrophysiology and arrhythmias over the last 40 years. In the second part of this paper, we illustrate how state-of-the-art open source computational modelling and simulation tools can be used to simulate multi-scale effects of drug-induced ion channel block in ventricular electrophysiology at the cellular, tissue and whole ventricular levels for different animal species. We believe that the use of computational modelling and simulation in combination with experimental techniques could be a powerful tool for the assessment of drug safety pharmacology.
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Affiliation(s)
- A. Corrias
- Oxford University Computing Laboratory, Wolfson Building, Parks Road, Oxford OX1 3QD, UK
| | - X. Jie
- Oxford University Computing Laboratory, Wolfson Building, Parks Road, Oxford OX1 3QD, UK
| | - L. Romero
- Instituto de Investigación Interuniversitario en Bioingeniería y Tecnología Orientada al Ser Humano, 6 Universidad Politécnica de Valencia (I3BH ), Valencia, Spain
| | - M. J. Bishop
- Oxford University Computing Laboratory, Wolfson Building, Parks Road, Oxford OX1 3QD, UK
| | - M. Bernabeu
- Oxford University Computing Laboratory, Wolfson Building, Parks Road, Oxford OX1 3QD, UK
| | - E. Pueyo
- Oxford University Computing Laboratory, Wolfson Building, Parks Road, Oxford OX1 3QD, UK
- Instituto de Investigación en Ingeniería de Aragón (I3A), Universidad de Zaragoza, Saragossa, Spain
| | - B. Rodriguez
- Oxford University Computing Laboratory, Wolfson Building, Parks Road, Oxford OX1 3QD, UK
- Author for correspondence ()
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10
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Salvi V, Karnad DR, Panicker GK, Kothari S. Update on the evaluation of a new drug for effects on cardiac repolarization in humans: issues in early drug development. Br J Pharmacol 2009; 159:34-48. [PMID: 19775279 DOI: 10.1111/j.1476-5381.2009.00427.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Following reports of death from cardiac arrhythmias with drugs like terfenadine and cisapride, the International Conference for Harmonization formulated a guidance (E14) document. This specifies that all new drugs must undergo a 'thorough QT/QTc' (TQT) study to detect drug-induced QT prolongation, a surrogate marker of ventricular tachycardia, especially torsades de pointes (TdPs). With better understanding of data from several completed TQT studies, regulatory requirements have undergone some changes since the E14 guidance was implemented in October 2005. This article reviews the implications of the E14 guidance and the changes in its interpretation including choice of baseline QT, demonstration of assay sensitivity, statistical analysis of the effect of new drug and positive control, and PK-PD modelling. Some issues like use of automated QT measurements remain unresolved. Pharmaceutical companies too are modifying Phase 1 studies to detect QTc liability early in order to save time and resources. After the E14 guidance, development of several drugs that prolong QTc by >5 ms is being abandoned by sponsors. However, all drugs that prolong the QT interval do not increase risk of TdP. Researchers in regulatory agencies, academia and industry are working to find better biomarkers of drug-induced TdP which could prevent many useful drugs from being prematurely abandoned. Drug-induced TdP is a rare occurrence. With fewer drugs that prolong QT interval reaching the licensing stage, knowing which of these drugs are torsadogenic is proving to be elusive. Thus, paradoxically, the effectiveness of the E14 guidance itself has made prospective validation of new biomarkers difficult.
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Affiliation(s)
- Vaibhav Salvi
- Quintiles ECG Services, Andheri (East), Mumbai, India.
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11
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Yokoyama H, Nakamura Y, Iwasaki H, Nagayama Y, Hoshiai K, Mitsumori Y, Sugiyama A. Effects of Acute Intravenous Administration of Pentamidine, a Typical hERG-Trafficking Inhibitor, on the Cardiac Repolarization Process of Halothane-Anesthetized Dogs. J Pharmacol Sci 2009; 110:476-82. [DOI: 10.1254/jphs.09071fp] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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12
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Obias-Manno D, Scott PE, Kaczmarczyk J, Miller M, Pinnow E, Lee-Bishop L, Jones-London M, Chapman K, Kallgren D, Uhl K. The Food and Drug Administration Office of Women's Health: Impact of Science on Regulatory Policy. J Womens Health (Larchmt) 2007; 16:807-17. [PMID: 17678451 DOI: 10.1089/jwh.2006.0135] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In 1994, the Food and Drug Administration Office of Women's Health (FDA-OWH) was created to provide leadership and policy direction for the Agency regarding issues of women's health. Within its first year, the FDA-OWH established a science program for women's health research, promoting the development of sound policy and regulation. In a little over a decade, the program has provided approximately 14 million dollars to fund more than 100 women's health research studies covering a broad range of health topics affecting women across their lifespan. Some studies, such as those elucidating drug effects on QT prolongation in women and drug-dietary supplement interaction, have had significant influence on regulatory decisions. Other studies have provided sound scientific data on sex and gender differences supporting FDA guidelines to protect women's health. This paper describes the science program at the FDA-OWH, providing examples of how funded research impacts regulatory policy.
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Affiliation(s)
- Dulce Obias-Manno
- Food and Drug Administration, FDA/OC/Office of Women's Health, Rockville, Maryland 20857, USA
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13
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Thomsen MB, Matz J, Volders PGA, Vos MA. Assessing the proarrhythmic potential of drugs: current status of models and surrogate parameters of torsades de pointes arrhythmias. Pharmacol Ther 2006; 112:150-70. [PMID: 16714061 DOI: 10.1016/j.pharmthera.2005.04.009] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Accepted: 04/06/2005] [Indexed: 02/08/2023]
Abstract
Torsades de pointes (TdP) is a potentially lethal cardiac arrhythmia that can occur as an unwanted adverse effect of various pharmacological therapies. Before a drug is approved for marketing, its effects on cardiac repolarisation are examined clinically and experimentally. This paper expresses the opinion that effects on repolarisation duration cannot directly be translated to risk of proarrhythmia. Current safety assessments of drugs only involve repolarisation assays, however the proarrhythmic profile can only be determined in the predisposed model. The availability of these proarrhythmic animal models is emphasised in the present paper. It is feasible for the pharmaceutical industry to establish one or more of these proarrhythmic animal models and large benefits are potentially available if pharmaceutical industries and patient-care authorities embraced these models. Furthermore, suggested surrogate parameters possessing predictive power of TdP arrhythmia are reviewed. As these parameters are not developed to finalisation, any meaningful study of the proarrhythmic potential of a new drug will include evaluation in an integrated model of TdP arrhythmia.
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Affiliation(s)
- Morten B Thomsen
- Department of Medical Physiology, Heart Lung Centre Utrecht, University Medical Centre Utrecht, Yalelaan 50, NL-3584 CM Utrecht, Netherlands.
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14
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Shah RR, Hondeghem LM. Refining detection of drug-induced proarrhythmia: QT interval and TRIaD. Heart Rhythm 2005; 2:758-72. [PMID: 15992736 DOI: 10.1016/j.hrthm.2005.03.023] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2005] [Accepted: 03/27/2005] [Indexed: 01/10/2023]
Abstract
QT interval prolongation is so frequently associated with torsades de pointes (TdP) that it has come to be recognized as a surrogate marker of this unique tachyarrhythmia. However, not only does TdP not always follow QT interval prolongation, but TdP can occur even in the absence of a prolonged QT interval. Worse still, even shortening of the QT interval may be associated with serious arrhythmias (particularly ventricular tachycardia [VT] and ventricular fibrillation [VF]). It appears increasingly probable that the distinction between various ventricular tachyarrhythmias may be arbitrary, and drug-induced TdP, polymorphic VT, VT, catecholaminergic polymorphic VT, and VF may represent discrete entities within a spectrum of drug-induced proarrhythmia. Although they are differentiated by the coupling interval and the duration of QT interval, they appear to share a common substrate: a set of disturbances of repolarization characterized by Triangulation, Reverse use dependency, electrical Instability of the action potential, and Dispersion (TRIaD). It is becoming increasingly evident that augmentation of TRIaD, rather than changes in the duration of QT interval, provides the proarrhythmic substrate. In contrast, when not associated with an increase of TRIaD, QT interval prolongation can be an antiarrhythmic property. Electrophysiologically, augmentation of TRIaD can be explained by inhibition of hERG (human ether-a-go-go related gene) channel. Because drug-induced disturbances in repolarization commonly result from inhibition of hERG channels or I(Kr), hERG blockade and the resulting prolongation of QT interval are important properties of a drug to be studied. However, these need only be a concern if associated with TRIaD. More significantly, TRIaD so often precedes prolongation of action potential duration or QT interval and ventricular tachyarrhythmias that it should be considered a marker of proarrhythmia until proven otherwise, even in the absence of QT interval prolongation. Detecting drug-induced augmentation of TRIaD may offer an additional, more sensitive, and accurate indicator of the broader proarrhythmic potential of a drug than may QT interval prolongation alone.
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Affiliation(s)
- Rashmi R Shah
- Medicines and Healthcare Products Regulatory Agency, London, UK.
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15
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Antoniou T, Gough KA. Early-onset pentamidine-associated second-degree heart block and sinus bradycardia: case report and review of the literature. Pharmacotherapy 2005; 25:899-903. [PMID: 15927910 DOI: 10.1592/phco.2005.25.6.899] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Although various manifestations of pentamidine-induced cardiotoxicity have been reported, to our knowledge, second-degree heart block associated with this agent has not been described. In addition, cardiac adverse effects usually develop after at least 6 days of therapy. We describe a 54-year-old, human immunodeficiency virus-positive man with a history of sulfonamide allergy who received treatment with pentamidine for Pneumocystis jiroveci pneumonia. After only the third dose of pentamidine, it was noted that the patient's heart rate had decreased to 48 beats/minute. Subsequently, five episodes of Wenckebach (Mobitz type 1) heart block with a ventricular rate of 28 beats/minute were observed on continuous cardiac telemetry. Serum electrolyte and creatinine levels remained within normal limits. Within 4 days of discontinuing the pentamidine, the patient's heart rate stabilized at 80 beats/minute without further intervention. Clinicians should be vigilant when monitoring for cardiotoxicity in patients receiving pentamidine throughout the duration of therapy. In addition, they should continue to reserve its use for moderate-to-severe Pneumocystis jiroveci pneumonia for which trimethoprim-sulfamethoxazole is ineffective or contraindicated.
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Affiliation(s)
- Tony Antoniou
- Department of Family and Community Medicine, St. Michael's Hospital, Toronto, Ontario, Canada.
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16
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Cordes JS, Sun Z, Lloyd DB, Bradley JA, Opsahl AC, Tengowski MW, Chen X, Zhou J. Pentamidine reduces hERG expression to prolong the QT interval. Br J Pharmacol 2005; 145:15-23. [PMID: 15711592 PMCID: PMC1576113 DOI: 10.1038/sj.bjp.0706140] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Pentamidine, an antiprotozoal agent, has been traditionally known to cause QT prolongation and arrhythmias; however, its ionic mechanism has not been illustrated. In a stable HEK-293 cell line, we observed a concentration-dependent inhibition of the hERG current with an IC50 of 252 microM. In freshly isolated guinea-pig ventricular myocytes, pentamidine showed no effect on the L-type calcium current at concentrations up to 300 microM, with a slight prolongation of the action potential duration at this concentration. Since the effective concentrations of pentamidine on the hERG channel and APD were much higher than clinically relevant exposures (approximately 1 microM free or lower), we speculated that this drug might not prolong the QT interval through direct inhibition of I(Kr) channel. We therefore incubated hERG-HEK cells in 1 and 10 microM pentamidine-containing media (supplemented with 10% serum) for 48 h, and examined the hERG current densities in the vehicle control and pentamidine-treated cells. In all, 36 and 85% reductions of the current densities were caused by 1- and 10-microM pentamidine treatment (P<0.001 vs control), respectively. A similar level of reduction of the hERG polypeptides and a reduced intensity of the hERG protein on the surface membrane in treated cells were observed by Western blot analysis and laser-scanning confocal microscopy, respectively. Taken together, our data imply that chronic administration of pentamidine at clinically relevant exposure reduces the membrane expression of the hERG channel, which may most likely be the major mechanism of QT prolongation and torsade de pointes reported in man.
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Affiliation(s)
- Jason S Cordes
- Department of Safety Pharmacology, Pfizer Global Research and Development, Groton/New London Laboratories, MS 8274-1420, Eastern Point Road, Groton, CT 06340, U.S.A
| | - Zhuoqian Sun
- Department of Safety Pharmacology, Pfizer Global Research and Development, Groton/New London Laboratories, MS 8274-1420, Eastern Point Road, Groton, CT 06340, U.S.A
| | - David B Lloyd
- Department of Genomic and Proteomic Sciences, Pfizer Global Research and Development, Groton/New London Laboratories, MS 8274-1420, Eastern Point Road, Groton, CT 06340, U.S.A
| | - Jenifer A Bradley
- Department of Safety Pharmacology, Pfizer Global Research and Development, Groton/New London Laboratories, MS 8274-1420, Eastern Point Road, Groton, CT 06340, U.S.A
| | - Alan C Opsahl
- Department of Pathology, Pfizer Global Research and Development, Groton/New London Laboratories, MS 8274-1420, Eastern Point Road, Groton, CT 06340, U.S.A
| | - Mark W Tengowski
- Department of Pathology, Pfizer Global Research and Development, Groton/New London Laboratories, MS 8274-1420, Eastern Point Road, Groton, CT 06340, U.S.A
| | - Xian Chen
- Department of Safety Pharmacology, Pfizer Global Research and Development, Groton/New London Laboratories, MS 8274-1420, Eastern Point Road, Groton, CT 06340, U.S.A
| | - Jun Zhou
- Department of Safety Pharmacology, Pfizer Global Research and Development, Groton/New London Laboratories, MS 8274-1420, Eastern Point Road, Groton, CT 06340, U.S.A
- Author for correspondence:
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18
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Abstract
Drug-induced delay in ventricular repolarization and proarrhythmias have attracted considerable regulatory attention. The measure of delayed ventricular repolarization most frequently used clinically is the ability of the new chemical entity (NCE) to prolong the QTc interval on surface electrocardiogram. Before they can be approved, new chemical entities with systemic bioavailability require characterization for their potential to prolong the QTc interval. Inevitably, QTc interval prolongation has come to be recognized as a surrogate marker of the risk of torsade de pointes (TdP)--a unique form of potentially fatal polymorphic ventricular tachycardia. Although it is the best and the simplest clinical measure that is available at present, QTc interval is not a reliable surrogate of TdP. Intramyocardial dispersion of repolarization appears to play a more important role both in electrical stability of the ventricles and in arrhythmogenesis. The potential importance of myocardial dispersion of refractoriness in arrhythmogenesis has led to a number of attempts to assess it from the surface electrocardiogram. This review summarizes the evidence for and against the predictive value of one of these attempts-measurement of the so-called QT dispersion. Although the concept of QT dispersion is the best known and most widely investigated, it has also proved to be the least successful in predicting the risks of drug-induced TdP.
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Affiliation(s)
- Rashmi R Shah
- Medicines and Healthcare Products Regulatory Agency, Vauxhall, London SW8 5NQ, UK.
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19
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Abstract
Torsades de pointes (TdP) is a potentially life-threatening arrhythmia associated with not only antiarrhythmic drugs, but noncardiac drugs of many different classes. All these drugs prolong the QT interval by their blocking of the potassium channel I(Kr), and many are metabolized by the cytochrome P450 isoenzyme CYP3A4. Polypharmacy with other drugs utilizing the same enzyme, or inhibiting CYP3A4, can lead to TdP. A consistent finding of all the QT-prolonging drugs is predominance of TdP in women. Other risk factors for QT prolongation and TdP include hypokalemia, congestive heart failure, and structural heart disease. Knowledge of potential drug interactions and other risk factors for TdP can help in reducing the number of adverse events associated with the use of QT-prolonging drugs.
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Affiliation(s)
- Deborah L Wolbrette
- Milton S. Hershey Medical Center, Division of Cardiology, 500 University Drive/H047, Hershey, PA 17033, USA.
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20
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Kuryshev YA, Ficker E, Wang L, Hawryluk P, Dennis AT, Wible BA, Brown AM, Kang J, Chen XL, Sawamura K, Reynolds W, Rampe D. Pentamidine-Induced Long QT Syndrome and Block of hERG Trafficking. J Pharmacol Exp Ther 2004; 312:316-23. [PMID: 15340016 DOI: 10.1124/jpet.104.073692] [Citation(s) in RCA: 211] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The diamidine pentamidine is used to treat leishmaniasis, trypanosomiasis, and Pneumocystis carinii pneumonia. Treatment may be accompanied by prolongation of the QT interval of the electrocardiogram and torsades de pointes tachycardias. Up to now, it has been thought that therapeutic compounds causing QT prolongation are associated with direct block of the cardiac potassium channel human ether a-go-go-related gene (hERG), which encodes the alpha subunit of cardiac I(Kr) currents. We show that pentamidine has no acute effects on currents produced by hERG, KvLQT1/mink, Kv4.3, or SCNA5. Cardiac calcium currents and the guinea pig cardiac action potential were also not affected. After overnight exposure, however, pentamidine reduced hERG currents and inhibited trafficking and maturation of hERG with IC(50) values of 5 to 8 microM similar to therapeutic concentrations. Surface expression determined in a chemiluminescence assay was reduced on exposure to 10, 30, and 100 microM pentamidine by about 30, 40, and 70%, respectively. These effects were specific for hERG since expression of hKv1.5, KvLQT1/minK, and Kv4.3 was not altered. In isolated guinea pig ventricular myocytes, 10 microM pentamidine prolonged action potential duration APD(90) from 374.3 +/- 57.1 to 893.9 +/- 86.2 ms on overnight incubation. I(Kr) tail current density was reduced from 0.61 +/- 0.09 to 0.39 +/- 0.04 pA/pF. We conclude that pentamidine prolongs the cardiac action potential by block of hERG trafficking and reduction of the number of functional hERG channels at the cell surface. We propose that pentamidine, like arsenic trioxide, produces QT prolongation and torsades de pointes in patients by inhibition of hERG trafficking.
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Affiliation(s)
- Yuri A Kuryshev
- Rammelkamp Center, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH 44109-1998, USA
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21
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Abstract
Drug-induced QT interval prolongation is now a major concern in safety pharmacology. Regulatory authorities such as the US FDA and the European Medicines Agency require in vitro testing of all drug candidates against the potential risk for QT interval prolongation prior to clinical trials. Common in vitro methods include organ models (Langendorff heart), conventional electrophysiology on cardiac myocytes, and heterologous expression systems of human ether-a-go-go-related gene (hERG) channels. A novel approach is to study electrophysiological properties of cultured cardiac myocytes by micro-electrode arrays (MEA). This technology utilises multi channel recording from an array of embedded substrate-integrated extracellular electrodes using cardiac tissue from the ventricles of embryonic chickens. The detected field potentials allow a partial reconstruction of the shape and time course of the underlying action potential. In particular, the duration of action potentials of ventricular myocytes is closely related to the QT interval on an ECG. This novel technique was used to study reference substances with a reported QT interval prolonging effect. These substances were E4031, amiodarone, quinidine and sotalol. These substances show a significant prolongation of the field potential. However, verapamil, a typical 'false positive' when using the hERG assay does not cause any field potential prolongation using the MEA assay. Whereas the heterologous hERG assay limits cardiac repolarisation to just one channel, the MEA assay reflects the full range of mechanisms involved in cardiac action potential regulation. In summary, screening compounds in cardiac myocytes with the MEA technology against QT interval prolongation can overcome the problem of a single cell assay to potentially report 'false positives'.
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Affiliation(s)
- Thomas Meyer
- Multi Channel Systems MCS GmbH, Reutlingen, Germany.
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22
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Abstract
Microvolt-level T-wave alternans (TWA) is a new arrhythmia risk marker to assess subtle changes in repolarization that has been introduced for arrhythmia risk stratification. Recent experimental studies have demonstrated that it reflects a heartrate dependent increased spatial dispersion of repolarization associated with unidirectional conduction block, and reentry that may result in the occurrence of ventricular fibrillation. Clinical studies have convincingly demonstrated that TWA is closely related to arrhythmia induction in the electrophysiology (EP) laboratory as well as to the occurrence of spontaneous ventricular tachyarrhythmias in patients undergoing EP study. Subsequent studies showed that TWA-assessed noninvasively-is predictive of future arrhythmic events in patients with implanted ICDs as well as for ventricular tachyarrhythmias in patients with congestive heart failure without a prior history of arrhythmias. There is still controversy, however, about the predictive value of TWA in patients following acute myocardial infarction (MI). Several studies which differ in patient selection, pharmacologic treatment of the patients, and endpoint definitions, have reported conflicting results. Therefore, studies with a large number of unselected patients after acute MI on optimal treatment according to contemporary therapeutic guidelines as well as of patients with reduced left ventricular ejection fraction following MI are needed to define its role with regard to identifying patients who may benefit from primary preventive ICD therapy. Future research should also focus on evaluation of alternative methods to increase heart rate (i.e., pharmacological stimulation) in an attempt to reduce the proportion of incomplete tests in patients with insufficient increase in heart rate during exercise testing.
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Pharmacoepidemiology and drug safety. Pharmacoepidemiol Drug Saf 2003; 12:253-68. [PMID: 12733480 DOI: 10.1002/pds.789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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