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Heijman J, Ghezelbash S, Dobrev D. Investigational antiarrhythmic agents: promising drugs in early clinical development. Expert Opin Investig Drugs 2017; 26:897-907. [PMID: 28691539 PMCID: PMC6324729 DOI: 10.1080/13543784.2017.1353601] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
INTRODUCTION Although there have been important technological advances for the treatment of cardiac arrhythmias (e.g., catheter ablation technology), antiarrhythmic drugs (AADs) remain the cornerstone therapy for the majority of patients with arrhythmias. Most of the currently available AADs were coincidental findings and did not result from a systematic development process based on known arrhythmogenic mechanisms and specific targets. During the last 20 years, our understanding of cardiac electrophysiology and fundamental arrhythmia mechanisms has increased significantly, resulting in the identification of new potential targets for mechanism-based antiarrhythmic therapy. Areas covered: Here, we review the state-of-the-art in arrhythmogenic mechanisms and AAD therapy. Thereafter, we focus on a number of antiarrhythmic targets that have received significant attention recently: atrial-specific K+-channels, the late Na+-current, the cardiac ryanodine-receptor channel type-2, and the small-conductance Ca2+-activated K+-channel. We highlight for each of these targets available antiarrhythmic agents and the evidence for their antiarrhythmic effect in animal models and early clinical development. Expert opinion: Targeting AADs to specific subgroups of well-phenotyped patients is likely necessary to detect improved outcomes that may be obscured in the population at large. In addition, specific combinations of selective AADs may have synergistic effects and may enable a mechanism-based tailored antiarrhythmic therapy.
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Affiliation(s)
- Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Shokoufeh Ghezelbash
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
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Loo SK, Ch'ng ES, Md Salleh MS, Banham AH, Pedersen LM, Møller MB, Green TM, Wong KK. TRPM4 expression is associated with activated B cell subtype and poor survival in diffuse large B cell lymphoma. Histopathology 2017; 71:98-111. [DOI: 10.1111/his.13204] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 02/23/2017] [Indexed: 12/21/2022]
Affiliation(s)
- Suet K Loo
- Department of Immunology; School of Medical Sciences; Universiti Sains Malaysia; Kelantan Malaysia
| | - Ewe S Ch'ng
- Advanced Medical and Dental Institute; Universiti Sains Malaysia; Bertam Malaysia
| | - Md Salzihan Md Salleh
- Department of Pathology; School of Medical Sciences; Universiti Sains Malaysia; Kelantan Malaysia
| | - Alison H Banham
- Nuffield Division of Clinical Laboratory Sciences; Radcliffe Department of Medicine; University of Oxford; John Radcliffe Hospital; Oxford UK
| | - Lars M Pedersen
- Department of Haematology; Herlev University Hospital; Copenhagen Denmark
| | - Michael B Møller
- Department of Pathology; Odense University Hospital; Odense Denmark
| | - Tina M Green
- Department of Pathology; Odense University Hospital; Odense Denmark
| | - Kah K Wong
- Department of Immunology; School of Medical Sciences; Universiti Sains Malaysia; Kelantan Malaysia
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Rezazadeh S, Duff HJ. Genetic Determinants of Hereditary Bradyarrhythmias: A Contemporary Review of a Diverse Group of Disorders. Can J Cardiol 2017; 33:758-767. [PMID: 28545623 DOI: 10.1016/j.cjca.2017.03.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 03/03/2017] [Accepted: 03/10/2017] [Indexed: 11/25/2022] Open
Abstract
Bradyarrhythmia is a common clinical presentation. Although the majority of cases are acquired, genetic screening of families with bradyarrhythmia has led to the discovery of a growing number of causative hereditary mutations. These mutations can interfere with any of the steps required for the occurrence of each cardiac cycle, including generation of an action potential in the sinoatrial node, successful exit of the action potential from the node, propagation of the action potential throughout the atria until the depolarization waves reach the atrioventricular node, and finally transmission of the action potential to the ventricles through the His-Purkinje system. As expected, channelopathies are the predominant culprit for hereditary bradyarrhythmias, because they play a crucial role in action potential generation and propagation. Interestingly, there are an increasing number of genes that encode for various regulatory or structural cellular components that have been linked to hereditary bradyarrhythmias. Furthermore, population-based genetic screening has revealed that age-related conduction defects may in fact be caused by genetic predispositions rather than the simple process of aging. With recent advances in genetic testing and the creation of animal models, not only have we discovered new culprit genes but it has also has become evident that there are still significant gaps in our knowledge of cardiac pathophysiology. In this review, we discuss the clinical presentations of known hereditary bradyarrhythmias and their associated conditions in addition to detailing our current molecular understanding of the mechanisms by which they are manifested.
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Affiliation(s)
- Saman Rezazadeh
- Department of Cardiac Sciences and Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Henry J Duff
- Department of Cardiac Sciences and Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
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Hof T, Sallé L, Coulbault L, Richer R, Alexandre J, Rouet R, Manrique A, Guinamard R. TRPM4 non-selective cation channels influence action potentials in rabbit Purkinje fibres. J Physiol 2015; 594:295-306. [PMID: 26548780 DOI: 10.1113/jp271347] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 10/29/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The transient receptor potential melastatin 4 (TRPM4) inhibitor 9-phenanthrol reduces action potential duration in rabbit Purkinje fibres but not in ventricle. TRPM4-like single channel activity is observed in isolated rabbit Purkinje cells but not in ventricular cells. The TRPM4-like current develops during the notch and early repolarization phases of the action potential in Purkinje cells. ABSTRACT Transient receptor potential melastatin 4 (TRPM4) Ca(2+)-activated non-selective cation channel activity has been recorded in cardiomyocytes and sinus node cells from mammals. In addition, TRPM4 gene mutations are associated with human diseases of cardiac conduction, suggesting that TRPM4 plays a role in this aspect of cardiac function. Here we evaluate the TRPM4 contribution to cardiac electrophysiology of Purkinje fibres. Ventricular strips with Purkinje fibres were isolated from rabbit hearts. Intracellular microelectrodes recorded Purkinje fibre activity and the TRPM4 inhibitor 9-phenanthrol was applied to unmask potential TRPM4 contributions to the action potential. 9-Phenanthrol reduced action potential duration measured at the point of 50 and 90% repolarization with an EC50 of 32.8 and 36.1×10(-6) mol l(-1), respectively, but did not modulate ventricular action potentials. Inside-out patch-clamp recordings were used to monitor TRPM4 activity in isolated Purkinje cells. TRPM4-like single channel activity (conductance = 23.8 pS; equal permeability for Na(+) and K(+); sensitivity to voltage, Ca(2+) and 9-phenanthrol) was observed in 43% of patches from Purkinje cells but not from ventricular cells (0/16). Action potential clamp experiments performed in the whole-cell configuration revealed a transient inward 9-phenanthrol-sensitive current (peak density = -0.65 ± 0.15 pA pF(-1); n = 5) during the plateau phases of the Purkinje fibre action potential. These results show that TRPM4 influences action potential characteristics in rabbit Purkinje fibres and thus could modulate cardiac conduction and be involved in triggering arrhythmias.
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Affiliation(s)
- Thomas Hof
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, Unicaen, Normandie Université, EA 4650, Caen, France
| | - Laurent Sallé
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, Unicaen, Normandie Université, EA 4650, Caen, France
| | - Laurent Coulbault
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, Unicaen, Normandie Université, EA 4650, Caen, France
| | - Romain Richer
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, Unicaen, Normandie Université, EA 4650, Caen, France
| | - Joachim Alexandre
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, Unicaen, Normandie Université, EA 4650, Caen, France
| | - René Rouet
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, Unicaen, Normandie Université, EA 4650, Caen, France
| | - Alain Manrique
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, Unicaen, Normandie Université, EA 4650, Caen, France
| | - Romain Guinamard
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, Unicaen, Normandie Université, EA 4650, Caen, France
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