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Kraft M, Büscher A, Wiedmann F, L’hoste Y, Haefeli WE, Frey N, Katus HA, Schmidt C. Current Drug Treatment Strategies for Atrial Fibrillation and TASK-1 Inhibition as an Emerging Novel Therapy Option. Front Pharmacol 2021; 12:638445. [PMID: 33897427 PMCID: PMC8058608 DOI: 10.3389/fphar.2021.638445] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 01/21/2021] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is the most common sustained arrhythmia with a prevalence of up to 4% and an upwards trend due to demographic changes. It is associated with an increase in mortality and stroke incidences. While stroke risk can be significantly reduced through anticoagulant therapy, adequate treatment of other AF related symptoms remains an unmet medical need in many cases. Two main treatment strategies are available: rate control that modulates ventricular heart rate and prevents tachymyopathy as well as rhythm control that aims to restore and sustain sinus rhythm. Rate control can be achieved through drugs or ablation of the atrioventricular node, rendering the patient pacemaker-dependent. For rhythm control electrical cardioversion and pharmacological cardioversion can be used. While electrical cardioversion requires fasting and sedation of the patient, antiarrhythmic drugs have other limitations. Most antiarrhythmic drugs carry a risk for pro-arrhythmic effects and are contraindicated in patients with structural heart diseases. Furthermore, catheter ablation of pulmonary veins can be performed with its risk of intraprocedural complications and varying success. In recent years TASK-1 has been introduced as a new target for AF therapy. Upregulation of TASK-1 in AF patients contributes to prolongation of the action potential duration. In a porcine model of AF, TASK-1 inhibition by gene therapy or pharmacological compounds induced cardioversion to sinus rhythm. The DOxapram Conversion TO Sinus rhythm (DOCTOS)-Trial will reveal whether doxapram, a potent TASK-1 inhibitor, can be used for acute cardioversion of persistent and paroxysmal AF in patients, potentially leading to a new treatment option for AF.
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Affiliation(s)
- Manuel Kraft
- Department of Cardiology, University of Heidelberg, Heidelberg, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany
- HCR, Heidelberg Center for Heart Rhythm Disorders, University of Heidelberg, Heidelberg, Germany
| | - Antonius Büscher
- Clinic for Cardiology II: Electrophysiology, University Hospital Münster, Münster, Germany
| | - Felix Wiedmann
- Department of Cardiology, University of Heidelberg, Heidelberg, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany
- HCR, Heidelberg Center for Heart Rhythm Disorders, University of Heidelberg, Heidelberg, Germany
| | - Yannick L’hoste
- Department of Cardiology, University of Heidelberg, Heidelberg, Germany
- HCR, Heidelberg Center for Heart Rhythm Disorders, University of Heidelberg, Heidelberg, Germany
| | - Walter E. Haefeli
- Department of Clinical Pharmacology and Pharmacoepidemiology, University of Heidelberg, Heidelberg, Germany
| | - Norbert Frey
- Department of Cardiology, University of Heidelberg, Heidelberg, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany
- HCR, Heidelberg Center for Heart Rhythm Disorders, University of Heidelberg, Heidelberg, Germany
| | - Hugo A. Katus
- Department of Cardiology, University of Heidelberg, Heidelberg, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany
- HCR, Heidelberg Center for Heart Rhythm Disorders, University of Heidelberg, Heidelberg, Germany
| | - Constanze Schmidt
- Department of Cardiology, University of Heidelberg, Heidelberg, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany
- HCR, Heidelberg Center for Heart Rhythm Disorders, University of Heidelberg, Heidelberg, Germany
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Citerni C, Kirchhoff J, Olsen LH, Sattler SM, Grunnet M, Edvardsson N, Bentzen BH, Diness JG. Inhibition of K Ca2 and K v11.1 Channels in Pigs With Left Ventricular Dysfunction. Front Pharmacol 2020; 11:556. [PMID: 32435191 PMCID: PMC7219273 DOI: 10.3389/fphar.2020.00556] [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] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 04/14/2020] [Indexed: 12/17/2022] Open
Abstract
Background Inhibition of KCa2 channels, conducting IKCa, can convert atrial fibrillation (AF) to sinus rhythm and protect against its induction. IKCa inhibition has been shown to possess functional atrial selectivity with minor effects on ventricles. Under pathophysiological conditions with ventricular remodeling, however, inhibiting IKCa can exhibit both proarrhythmic and antiarrhythmic ventricular effects. The aim of this study was to evaluate the effects of the IKCa inhibitor AP14145, when given before or after the IKr blocker dofetilide, on cardiac function and ventricular proarrhythmia markers in pigs with or without left ventricular dysfunction (LVD). Methods Landrace pigs were randomized into an AF group (n = 6) and two control groups: SHAM1 (n = 8) and SHAM2 (n = 4). AF pigs were atrially tachypaced (A-TP) for 43 ± 4 days until sustained AF and LVD developed. A-TP and SHAM1 pigs received 20 mg/kg AP14145 followed by 100 µg/kg dofetilide whereas SHAM2 pigs received the same drugs in the opposite order. Proarrhythmic markers such as short-term variability of QT (STVQT) and RR (STVRR) intervals, and the number of premature ventricular complexes (PVCs) were measured at baseline and after administration of drugs. The influence on cardiac function was assessed by measuring cardiac output, stroke volume, and relevant echocardiographic parameters. Results IKCa inhibition by AP14145 did not increase STVQT or STVRR in any of the pigs. IKr inhibition by dofetilide markedly increased STVQT in the A-TP pigs, but not in SHAM operated pigs. Upon infusion of AP14145 the number of PVCs decreased or remained unchanged both when AP14145 was infused after baseline and after dofetilide. Conversely, the number of PVCs increased or remained unchanged upon dofetilide infusion. Neither AP14145 nor dofetilide affected relevant echocardiographic parameters, cardiac output, or stroke volume in any of the groups. Conclusion IKCa inhibition with AP14145 was not proarrhythmic in healthy pigs, or in the presence of LVD resulting from A-TP. In pigs already challenged with 100 µg/kg dofetilide there were no signs of proarrhythmia when 20 mg/kg AP14145 were infused. KCa2 channel inhibition did not affect cardiac function, implying that KCa2 inhibitors can be administered safely also in the presence of LV dysfunction.
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Affiliation(s)
- Carlotta Citerni
- Biomedical Institute, University of Copenhagen, Copenhagen, Denmark.,Acesion Pharma, Copenhagen, Denmark
| | | | - Lisbeth Høier Olsen
- Department of Veterinary Disease Biology, University of Copenhagen, Frederiksberg, Denmark
| | - Stefan Michael Sattler
- Biomedical Institute, University of Copenhagen, Copenhagen, Denmark.,Department of Cardiology, Heart Center, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | | | - Nils Edvardsson
- Acesion Pharma, Copenhagen, Denmark.,Department of Molecular and Clinical Medicine, Sahlgrenska Academy at Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Bo Hjorth Bentzen
- Biomedical Institute, University of Copenhagen, Copenhagen, Denmark.,Acesion Pharma, Copenhagen, Denmark
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Antiarrhythmic Effects of Combining Dofetilide and Ranolazine in a Model of Acutely Induced Atrial Fibrillation in Horses. J Cardiovasc Pharmacol 2019; 71:26-35. [PMID: 29068807 PMCID: PMC5768216 DOI: 10.1097/fjc.0000000000000541] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Supplemental Digital Content is Available in the Text. Background: Antiarrhythmic compounds against atrial fibrillation (AF) often have reduced efficacy and may display cardiac and/or noncardiac toxicity. Efficacy can be improved by combining 2 compounds with distinct mechanisms, and it may be possible to use lower doses of each compound, thereby reducing the likelihood of adverse side effects. The purpose of this study was to investigate whether the effective doses of dofetilide and ranolazine can be reduced if the drugs are combined. Methods: Dofetilide, ranolazine, and a combination of these were administered in 4 incremental dosing regimens to horses with acutely pacing-induced AF. Time to cardioversion, atrial effective refractory period, and AF vulnerability and duration were assessed. Results: Of 8 horses, 6 cardioverted to sinus rhythm after infusion with a combination of 0.889 μg/kg dofetilide and 0.104 mg/kg ranolazine. Two horses cardioverted with 0.104 mg/kg ranolazine alone, and 3 cardioverted with 0.889 μg/kg dofetilide alone. The combination therapy decreased AF vulnerability (P < 0.05) and AF duration (P < 0.05). No change in atrial effective refractory period was detected with any of the drugs. Conclusions: The combination of dofetilide and ranolazine showed increased antiarrhythmic effects on acutely induced AF in horses, affecting time to cardioversion, AF vulnerability, and AF duration.
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Cao DX, Kohatsu A, Eng L, Mei K, Dinh J, Mok I, Moreau N, Le A, Shin J. Evaluation of initial dofetilide dosing recommendation based on actual body weight in overweight and obese patients. J Clin Pharm Ther 2015; 40:635-9. [DOI: 10.1111/jcpt.12321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 08/07/2015] [Indexed: 11/25/2022]
Affiliation(s)
- D. X. Cao
- Department of Pharmacy Practice; Loma Linda University School of Pharmacy; Loma Linda CA USA
| | - A. Kohatsu
- Department of Pharmacy Practice; Loma Linda University School of Pharmacy; Loma Linda CA USA
| | - L. Eng
- Department of Clinical Pharmacy; School of Pharmacy; University of California, San Francisco; San Francisco CA USA
| | - K. Mei
- Department of Clinical Pharmacy; School of Pharmacy; University of California, San Francisco; San Francisco CA USA
| | - J. Dinh
- Department of Clinical Pharmacy; School of Pharmacy; University of California, San Francisco; San Francisco CA USA
| | - I. Mok
- Department of Clinical Pharmacy; School of Pharmacy; University of California, San Francisco; San Francisco CA USA
| | - N. Moreau
- Department of Clinical Pharmacy; School of Pharmacy; University of California, San Francisco; San Francisco CA USA
| | - A. Le
- Department of Clinical Pharmacy; School of Pharmacy; University of California, San Francisco; San Francisco CA USA
| | - J. Shin
- Department of Clinical Pharmacy; School of Pharmacy; University of California, San Francisco; San Francisco CA USA
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Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Kay GN, Le Huezey JY, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, Wann LS. 2011 ACCF/AHA/HRS Focused Updates Incorporated Into the ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation. Circulation 2011; 123:e269-367. [PMID: 21382897 DOI: 10.1161/cir.0b013e318214876d] [Citation(s) in RCA: 595] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Kay GN, Le Huezey JY, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, Wann LS. 2011 ACCF/AHA/HRS Focused Updates Incorporated Into the ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation. J Am Coll Cardiol 2011; 57:e101-98. [PMID: 21392637 DOI: 10.1016/j.jacc.2010.09.013] [Citation(s) in RCA: 642] [Impact Index Per Article: 49.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Morita N, Tanaka K, Yodogawa K, Hayashi M, Akutsu K, Yamamoto T, Satoh N, Kobayashi Y, Katoh T, Takano T. Effect of nifekalant for acute conversion of atrial flutter: the possible termination mechanism of typical atrial flutter. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2007; 30:1242-53. [PMID: 17897127 DOI: 10.1111/j.1540-8159.2007.00846.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Nifekalant is a class III antiarrhythmic drug, which is usually used for suppression of ventricular tachycardia (VT) and fibrillation. We studied the efficacy of nifekalant for acute conversion of atrial flutter (AFL) in a prospective, open label study in the intensive care unit (ICU) of cardiovascular medicine. METHODS This study consisted of 31 patients. Twenty-six patients (84%) suffered from structural heart diseases. AFL was developed in 15 patients (48%) while on antiarrhythmic therapy with class IA or IC drugs (I-AFL group) for suppressing atrial fibrillation (AF) and in the remaining patients without such drugs (S-AFL group). Patients with prolonged QT interval, hypokalemia were excluded. All patients received one dose of 0.3 mg/kg of nifekalant over 10 minutes under continuous ambulatory monitoring. Four patients with common AFL in each group received nifekalant during electrophysiologic (EP) study. RESULTS Nifekalant had an overall AFL conversion efficacy of 77.4% within 60 minutes. Eleven patients in S-AFL group (68.8%) and 13 patients in I-AFL group (86.7%) could be converted with mean conversion times of 10.8 +/- 6.2 and 15.0 +/- 8.0 minutes, respectively (n.s.). Conversion rate was significantly higher in patients with a short duration of arrhythmia. The two modes of AFL termination were mainly demonstrated and the preferential mode significantly differed between the two groups. One patient in each group with excessive QT prolongation (6.5%) developed torsade de pointes (TdP), requiring electrical shock in one patient (3.3%). CONCLUSIONS Nifekalant can be used for conversion of AFL with a potent efficacy even in patients with structural heart diseases. However, caution should be required for developing TdP.
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Affiliation(s)
- Norishige Morita
- Intensive and Coronary Care Unit, Nippon Medical School, Tokyo, Japan.
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Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Le Heuzey JY, Kay GN, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, Wann S. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation-executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients with Atrial Fibrillation). Eur Heart J 2007; 27:1979-2030. [PMID: 16885201 DOI: 10.1093/eurheartj/ehl176] [Citation(s) in RCA: 362] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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ACC/AHA/ESC: Guías de Práctica Clínica 2006 para el manejo de pacientes con fibrilación auricular. Versión resumida. Rev Esp Cardiol 2006. [DOI: 10.1157/13096583] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Le Heuzey JY, Kay GN, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, Wann S, Smith SC, Jacobs AK, Adams CD, Anderson JL, Antman EM, Halperin JL, Hunt SA, Nishimura R, Ornato JP, Page RL, Riegel B, Priori SG, Blanc JJ, Budaj A, Camm AJ, Dean V, Deckers JW, Despres C, Dickstein K, Lekakis J, McGregor K, Metra M, Morais J, Osterspey A, Tamargo JL, Zamorano JL. ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation 2006; 114:e257-354. [PMID: 16908781 DOI: 10.1161/circulationaha.106.177292] [Citation(s) in RCA: 1381] [Impact Index Per Article: 76.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Le Heuzey JY, Kay GN, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, Wann S, Smith SC, Jacobs AK, Adams CD, Anderson JL, Antman EM, Hunt SA, Nishimura R, Ornato JP, Page RL, Riegel B, Priori SG, Blanc JJ, Budaj A, Camm AJ, Dean V, Deckers JW, Despres C, Dickstein K, Lekakis J, McGregor K, Metra M, Morais J, Osterspey A, Zamorano JL. ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation—Executive Summary. J Am Coll Cardiol 2006; 48:854-906. [PMID: 16904574 DOI: 10.1016/j.jacc.2006.07.009] [Citation(s) in RCA: 717] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Makaryus AN, Byrns K, Makaryus MN, Natarajan U, Singer C, Goldner B. Effect of ciprofloxacin and levofloxacin on the QT interval: is this a significant "clinical" event? South Med J 2006; 99:52-6. [PMID: 16466123 DOI: 10.1097/01.smj.0000197124.31174.7e] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The widespread use of the fluoroquinolones has raised the question of the cardiac safety of these medications. This widespread use of this class of antibiotics has displayed their safety profile, which is actually more favorable than many other drug classes. The cardiac toxicity issue at the center of this discussion is the prolongation of the QT interval leading to torsade de pointes. Ciprofloxacin and levofloxacin, two of the more commonly used fluoroquinolones, are considered less likely than other fluoroquinolones to prolong the QT interval. The authors set out to evaluate the effect on the QT interval of patients after administration of ciprofloxacin and levofloxacin. METHODS A prospective evaluation of 38 consecutive patients evaluated by the infectious disease service and receiving either ciprofloxacin or levofloxacin was undertaken. Twelve-lead electrocardiograms were obtained at baseline and at least 48 hours after the first dose of the antibiotic was administered. Both the longest QT interval and the mean QT interval were evaluated. To account for variations in heart rate, the corrected QT interval was calculated by using Bazett's formula (QTc = QT(square root of) R-R). Statistical analysis was undertaken to assess for the presence of a change after the administration of the antibiotic. RESULTS Thirty-eight patients (mean age, 65 +/- 19 years), 23 women and 15 men, were studied. There was a small but significant increase in the longest QTc intervals over baseline in patients receiving levofloxacin; there was no significant change in the mean QTc interval. However, one patient who received levofloxacin was, statistically, an outlier and, on retrospective analysis, had demonstrated severe electrolyte disturbances at the time of the study. When this patient was excluded, the increase in the longest QTc interval was not significant. Patients receiving ciprofloxacin did not demonstrate any significant change in the longest QTc interval or mean QTc interval. CONCLUSIONS Neither levofloxacin nor ciprofloxacin significantly prolonged the mean QTc interval over baseline. When electrolyte deficiencies in one of the patients evaluated were taken into account, this also held true for the longest QTc interval. There is, therefore, evidence that taking ciprofloxacin or levofloxacin, assuming that there are not any concurrent risk factors, will not cause a significant prolongation in the QT interval.
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Affiliation(s)
- Amgad N Makaryus
- North Shore-Long Island Jewish Health System, Division of Cardiology, Electrophysiology Section, Long Island Jewish Medical Center, 270-05 76th Avenue, New Hyde Park, NY 11040, USA
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Boriani G, Diemberger I, Biffi M, Martignani C, Branzi A. Pharmacological cardioversion of atrial fibrillation: current management and treatment options. Drugs 2005; 64:2741-62. [PMID: 15563247 DOI: 10.2165/00003495-200464240-00003] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Atrial fibrillation (AF) is the most common form of arrhythmia, carrying high social costs. It is usually first seen by general practitioners or in emergency departments. Despite the availability of consensus guidelines, considerable variations exist in treatment practice, especially outside specialised cardiological settings. Cardioversion to sinus rhythm aims to: (i) restore the atrial contribution to ventricular filling/output; (ii) regularise ventricular rate; and (iii) interrupt atrial remodelling. Cardioversion always requires careful assessment of potential proarrhythmic and thromboembolic risks, and this translates into the need to personalise treatment decisions. Among the many clinical variables that affect strategy selection, time from onset is crucial. In selected patients, pharmacological cardioversion of recent-onset AF can be a safely used, feasible and effective approach, even in internal medicine and emergency departments. In most cases of recent-onset AF, pharmacological cardioversion provides an important--and probably more cost effective--alternative to electrical cardioversion, which can then be employed as a second-line therapy for nonresponders. Class IC agents (flecainide or propafenone), which can be safely used in hospitalised patients with recent-onset AF without left ventricular dysfunction, can provide rapid conversion to sinus rhythm after either intravenous administration or oral loading. Although intravenous amiodarone requires longer conversion times, it is still the standard treatment for patients with heart failure. Ibutilide also provides good conversion rates and could be used for AF patients with left ventricular dysfunction (were it not for high costs). For long-lasting AF most pharmacological treatments have only limited efficacy and electrical cardioversion remains the gold standard in this setting. However, a widely used strategy involves pretreatment with amiodarone in the weeks before planned electrical cardioversion: this provides optimal prophylaxis and can sometimes even restore sinus rhythm. Dofetilide may also be capable of restoring sinus rhythm in up to 25-30% of patients and can be used in patients with heart failure. The potential risk of proarrhythmia increases the need for careful therapeutic decision making and management of pharmacological cardioversion. The results of recent trials (AFFIRM [Atrial Fibrillation Follow-up Investigation of Rhythm Management] and RACE [Rate Control versus Electrical Cardioversion for Persistent Atrial Fibrillation]) on rate versus rhythm control strategies in the long term have led to a generalised shift in interest towards rate control. Although carefully designed studies are required to better define the role of pharmacological rhythm control in specific AF settings, this alternative option remains a recommendable strategy for many patients, especially those in acute care.
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Affiliation(s)
- Giuseppe Boriani
- Institute of Cardiology, University of Bologna, Azienda Ospedaliera S. Orsola-Malpighi, Bologna, Italy.
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Gould PA, Power J, Broughton A, Kaye DM. Review of the current management of atrial fibrillation. Expert Opin Pharmacother 2003; 4:1889-99. [PMID: 14596645 DOI: 10.1517/14656566.4.11.1889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Atrial fibrillation (AF) is the most common sustained arrhythmia. Its prevalence is increasing and accordingly, so is its burden on healthcare systems throughout the world. The pathophysiology of AF is complex and poorly understood, which of itself presents a major challenge to the management of this important condition. AF is associated with increased morbidity and mortality, particularly in patients with underlying left ventricular dysfunction. Once AF occurs, it is often difficult to 'cure' and as such, the major focus of therapy is currently divided essentially between a rate control strategy and a need to revert to and maintain sinus rhythm. Both approaches seek to minimise the associated symptoms and complications. Over the past two decades, numerous pharmacological approaches to the management of AF have been employed, many of which have been shown to be relatively ineffective or confounded by major complications. Accordingly, recent research and interest has focused on non-pharmacological electrophysiological therapies to either cure AF or improve symptoms. This review summarises the current approaches to the management AF and provides some new insights into emerging therapies for this common clinical problem.
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Affiliation(s)
- Paul A Gould
- Department of Cardiovascular Medicine, Alfred Hospital, Commercial Rd, Melbourne 3004, Victoria, Australia.
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Cobbe SM, Campbell RW, Camm AJ, Nathan AW, Rowland E, Bloch-Thomsen PE, Møller M, Jordaens L. Effects of intravenous dofetilide on induction of atrioventricular re-entrant tachycardia. Heart 2001; 86:522-6. [PMID: 11602544 PMCID: PMC1729955 DOI: 10.1136/heart.86.5.522] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
OBJECTIVE To assess the efficacy and safety of intravenous dofetilide in preventing induction of atrioventricular re-entrant tachycardia. DESIGN A multicentre, open, dose ranging trial. Fifty one patients with electrically inducible atrioventricular re-entrant tachycardia were allocated to one of five doses of dofetilide (1.5, 3, 6, 9, and 15 microgram/kg), two thirds of the dofetilide dose being given over a 15 minute loading period and the remainder over a 45 minute maintenance period. MAIN OUTCOME MEASURE Responders were defined as patients in whom dofetilide prevented reinduction of atrioventricular re-entrant tachycardia at the end of the infusion. RESULTS Intravenous dofetilide had no effect on tachycardia inducibility at the two lower doses (1.5 and 3 microgram/kg) but prevented the reinduction of tachycardia at the three higher doses (6, 9, and 15 microgram/kg) at a rate of 36% (11/31). There was a clear relation between plasma dofetilide concentrations and efficacy (p = 0.009). In non-responders, dofetilide increased the cycle length of induced atrioventricular re-entrant tachycardia. Dofetilide increased the atrial and ventricular effective refractory periods, as well as the antegrade and retrograde effective refractory period of the accessory pathway. Treatment related side effects were reported in four patients, one with a new sustained incessant supraventricular tachycardia. CONCLUSIONS Dofetilide shows promise as an agent for the prevention of atrioventricular re-entrant tachycardia in patients without structural heart disease.
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Affiliation(s)
- S M Cobbe
- Department of Medical Cardiology, Glasgow Royal Infirmary, 10 Alexandra Parade, Glasgow G31 2ER, UK.
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Fuster V, Rydén LE, Asinger RW, Cannom DS, Crijns HJ, Frye RL, Halperin JL, Kay GN, Klein WW, Lévy S, McNamara RL, Prystowsky EN, Wann LS, Wyse DG, Gibbons RJ, Antman EM, Alpert JS, Faxon DP, Fuster V, Gregoratos G, Hiratzka LF, Jacobs AK, Russell RO, Smith SC, Klein WW, Alonso-Garcia A, Blomström-Lundqvist C, de Backer G, Flather M, Hradec J, Oto A, Parkhomenko A, Silber S, Torbicki A. ACC/AHA/ESC Guidelines for the Management of Patients With Atrial Fibrillation: Executive Summary A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines and Policy Conferences (Committee to Develop Guidelines for the Management of Patients With Atrial Fibrillation)Developed in Collaboration With the North American Society of Pacing and Electrophysiology. Circulation 2001. [DOI: 10.1161/circ.104.17.2118] [Citation(s) in RCA: 557] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Fuster V, Rydén LE, Asinger RW, Cannom DS, Crijns HJ, Frye RL, Halperin JL, Kay GN, Klein WW, Lévy S, McNamara RL, Prystowsky EN, Wann LS, Wyse DG, Gibbons RJ, Antman EM, Alpert JS, Faxon DP, Fuster V, Gregoratos G, Hiratzka LF, Jacobs AK, Russell RO, Smith SC, Klein WW, Alonso-Garcia A, Blomström-Lundqvist C, De Backer G, Flather M, Hradec J, Oto A, Parkhomenko A, Silber S, Torbicki A. ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation: executive summary. A Report of the American College of Cardiology/ American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines and Policy Conferences (Committee to Develop Guidelines for the Management of Patients With Atrial Fibrillation): developed in Collaboration With the North American Society of Pacing and Electrophysiology. J Am Coll Cardiol 2001; 38:1231-66. [PMID: 11583910 DOI: 10.1016/s0735-1097(01)01587-x] [Citation(s) in RCA: 486] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Fuster V, Rydén LE, Asinger RW, Cannom DS, Crijns HJ, Frye RL, Halperin JL, Kay G, Klein WW, Lévy S, McNamara RL, Prystowsky EN, Wann L, Wyse D, Gibbons RJ, Antman EM, Alpert JS, Faxon DP, Fuster V, Gregoratos G, Hiratzka LF, Jacobs AK, Russell RO, Smith SC, Klein WW, Alonso-Garcia A, Blomström-Lundqvist C, De Backer G, Flather M, Hradec J, Oto A, Parkhomenko A, Silber S, Torbicki A. ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation31This document was approved by the American College of Cardiology Board of Trustees in August 2001, the American Heart Association Science Advisory and Coordinating Committee in August 2001, and the European Society of Cardiology Board and Committee for Practice Guidelines and Policy Conferences in August 2001.32When citing this document, the American College of Cardiology, the American Heart Association, and the European Society of Cardiology would appreciate the following citation format: Fuster V, Rydén LE, Asinger RW, Cannom DS, Crijns HJ, Frye RL, Halperin JL, Kay GN, Klein WW, Lévy S, McNamara RL, Prystowsky EN, Wann LS, Wyse DG. ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines and Policy Conferences (Committee to Develop Guidelines for the Management of Patients With Atrial Fibrillation). J Am Coll Cardiol 2001;38:XX-XX.33This document is available on the World Wide Web sites of the American College of Cardiology (www.acc.org), the American Heart Association (www.americanheart.org), the European Society of Cardiology (www.escardio.org), and the North American Society of Pacing and Electrophysiology (www.naspe.org). Single reprints of this document (the complete Guidelines) to be published in the mid-October issue of the European Heart Journal are available by calling +44.207.424.4200 or +44.207.424.4389, faxing +44.207.424.4433, or writing Harcourt Publishers Ltd, European Heart Journal, ESC Guidelines – Reprints, 32 Jamestown Road, London, NW1 7BY, United Kingdom. Single reprints of the shorter version (Executive Summary and Summary of Recommendations) published in the October issue of the Journal of the American College of Cardiology and the October issue of Circulation, are available for $5.00 each by calling 800-253-4636 (US only) or by writing the Resource Center, American College of Cardiology, 9111 Old Georgetown Road, Bethesda, Maryland 20814. To purchase bulk reprints specify version and reprint number (Executive Summary 71-0208; full text 71-0209) up to 999 copies, call 800-611-6083 (US only) or fax 413-665-2671; 1000 or more copies, call 214-706-1466, fax 214-691-6342; or E-mail: pubauth@heart.org. J Am Coll Cardiol 2001. [DOI: 10.1016/s0735-1097(01)01586-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
The prolonged QT syndromes are characterized by prolongation of the QT interval corrected for heart rate (QTc) on the surface electrocardiogram associated with T-wave abnormalities, relative bradycardia, and ventricular tachyarrhythmias, including polymorphic ventricular tachycardia and torsades de pointes. These patients tend to present with episodes of syncope, seizures, or sudden death typically triggered by exercise, emotion, noise, or, in some cases, sleep. These disorders of cardiac repolarization are commonly inherited, with the autosomal dominant form, Romano-Ward syndrome, most common. A rare autosomal recessive form associated with sensorineural deafness, Jervell and Lange-Nielsen syndrome, in which the cardiac disorder is autosomal dominant and deafness is a recessive trait, also occurs. The underlying genetic causes of these forms of prolonged QT interval syndromes are heterogeneous, with at least seven genes responsible for the clinical syndromes. All of the five genes identified to date encode ion channel proteins, suggesting this to be an ion channelopathy. In this review, the genetic basis of the prolonged QT interval syndromes will be discussed, genotype-phenotype correlations identified, and the approaches to genetic testing and treatments will be outlined.
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Affiliation(s)
- J A Towbin
- Department of Pediatrics (Cardiology), Baylor College of Medicine, Houston, Texas 77030, USA
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Li D, Bénardeau A, Nattel S. Contrasting efficacy of dofetilide in differing experimental models of atrial fibrillation. Circulation 2000; 102:104-12. [PMID: 10880422 DOI: 10.1161/01.cir.102.1.104] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Rapid atrial pacing (RAP) and congestive heart failure (CHF) produce different experimental substrates for atrial fibrillation (AF). We tested the hypothesis that AF maintained by different substrates responds differently to antiarrhythmic-drug therapy. METHODS AND RESULTS The class III antiarrhythmic agent dofetilide was given intravenously at doses of 10 (D10) and 80 (D80) microg/kg to dogs with AF induced either (1) after 7 days of RAP at 400 bpm or (2) in the presence of CHF induced by rapid ventricular pacing. Dofetilide terminated AF in all CHF dogs, but D10 failed to terminate AF in any RAP dog, and D80 terminated AF in only 1 of 5 RAP dogs (20%) (P<0.01 for efficacy in CHF versus RAP dogs). Dofetilide was highly effective in preventing AF induction by atrial burst pacing in dogs with CHF but was totally ineffective in dogs with RAP. Dofetilide increased atrial effective refractory period and AF cycle length to a greater extent in CHF dogs. Epicardial mapping with 248 bipolar electrodes showed that CHF-related AF was often due to macroreentry, with dofetilide terminating AF by causing block in reentry circuits. RAP-related AF was due to multiple-wave front reentry, with dofetilide slowing reentry and decreasing the number of simultaneous waves, but not sufficiently to stop AF. CONCLUSIONS The mechanism underlying AF importantly influences dofetilide efficacy. The dependence of drug efficacy in AF on the underlying mechanism has potentially significant implications for antiarrhythmic drug use and development and may explain the well-known therapeutic resistance of longer-duration AF.
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Affiliation(s)
- D Li
- Research Center and Department of Medicine, Montreal Heart Institute Quebec, Canada
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Houltz B, Darpö B, Swedberg K, Blomström P, Crijns HJ, Jensen SM, Svernhage E, Edvardsson N. Comparison of QT dispersion during atrial fibrillation and sinus rhythm in the same patients, at normal and prolonged ventricular repolarization. Europace 2000; 2:20-31. [PMID: 11225593 DOI: 10.1053/eupc.1999.0068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
AIMS Drug-induced increase in QT dispersion has been associated with increased risk of ventricular proarrhythmia. The aim of the present study was to compare QT dispersion during atrial fibrillation and sinus rhythm in the same patients at normal and prolonged ventricular repolarization. METHODS AND RESULTS Sixty-one patients who had had chronic atrial fibrillation for 8 +/- 14 months received a 6 h infusion of the Ikr-blocker almokalant, the first 90 min of which are used for this analysis. The following day, after conversion to sinus rhythm, by almokalant (n = 19) or direct current cardioversion (n=42), an identical 90 min infusion was administered. Prior to infusion, there was no difference in precordial QT dispersion between atrial fibrillation and sinus rhythm (29 +/- 12 vs 36 +/- 17 ms, P=ns). During infusion, at prolonged repolarization, the increase in QT dispersion was greater during sinus rhythm than during atrial fibrillation (58 +/- 49 vs 30 +/- 15 ms, P=0.0011, after 30 min infusion). No correlation was found between QT dispersion and the QT or RR interval. CONCLUSION QT dispersion during atrial fibrillation does not differ from QT dispersion during sinus rhythm during normal repolarization. while measurement of QT dispersion during prolonged repolarization, induced by an Ikr-blocker, yielded larger values during sinus rhythm than during atrial fibrillation.
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Affiliation(s)
- B Houltz
- Department of Medicine, Sahlgrenska University Hospital, Ostra, Göteborg, Sweden
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Abstract
OBJECTIVE To review published reports on the pharmacology and clinical use of dofetilide in the management of cardiac dysrhythmias. DATA SOURCES A MEDLINE search (January 1966-June 1999) was performed using dofetilide and UK-68,798 as key words. English-language articles were identified, and the references of these articles were used to further identify pertinent articles. STUDY SELECTION All acquired studies and reviews discussing the pharmacology, pharmacokinetics, chemistry, and clinical efficacy of dofetilide were reviewed. DATA EXTRACTION Articles were selected based on quality of review of the pharmacology and clinical use of dofetilide. Given the paucity of data on the clinical pharmacology and use of dofetilide, most articles obtained were used, including abstracts when full reports were not available. DATA SYNTHESIS Dofetilide is a relatively specific class III antiarrhythmic agent. It increases action potential duration and effective refractory period without impacting conduction velocity. These actions of dofetilide are explained by its ability to inhibit the rapid component of the delayed, outward-rectifying potassium current, thus blocking the efflux of potassium during repolarization. Introductory investigations suggest that dofetilide may be of use in treating and preventing atrial dysrhythmias such as atrial fibrillation, atrial flutter, and paroxysmal supraventricular tachycardia. Dofetilide may also have a role in preventing ventricular tachycardia from occurring. Some data also suggest that dofetilide may improve the morbidity of heart failure patients. Currently, the most troublesome adverse effect of dofetilide is its propensity to induce ventricular proarrhythmias, especially torsade de pointes. CONCLUSIONS Based on the data currently available, dofetilide should have a role in the pharmacotherapy of cardiac dysrhythmias, especially those of atrial origin. More data on its efficacy and tolerability are needed, however, to fully delineate dofetilide's role amid currently available antiarrhythmic agents.
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Affiliation(s)
- J S Kalus
- College of Pharmacy, University of Toledo, OH 43606, USA
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Drolet B, Zhang S, Deschênes D, Rail J, Nadeau S, Zhou Z, January CT, Turgeon J. Droperidol lengthens cardiac repolarization due to block of the rapid component of the delayed rectifier potassium current. J Cardiovasc Electrophysiol 1999; 10:1597-604. [PMID: 10636190 DOI: 10.1111/j.1540-8167.1999.tb00224.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Torsades de pointes have been observed during treatment with droperidol, a butyrophenone neuroleptic agent. Our objectives were (1) to characterize the effects of droperidol on cardiac repolarization and (2) to evaluate effects of droperidol on a major time-dependent outward potassium current involved in cardiac repolarization (I(K)r). METHODS AND RESULTS Isolated, buffer-perfused guinea pig hearts (n = 32) were stimulated at different pacing cycle lengths (150 to 250 msec) and exposed to droperidol in concentrations ranging from 10 to 300 nmol/L. Droperidol increased monophasic action potential duration measured at 90% repolarization (MAPD90) in a concentration-dependent manner by 9.8+/-2.3 msec (7.3%+/-0.7%) at 10 nmol/L but by 32.7+/-3.6 msec (25.7%+/-2.2%) at 300 nmol/L (250-msec cycle length). Increase in MAPD90 also was reverse frequency dependent. As noted previously, droperidol 300 nmol/L increased MAPD90 by 32.7+/-3.6 msec (25.7%+/-2.2%) at a pacing cycle length of 250 msec but by only 14.1+/-1.3 msec (13.6%+/-2.3%) at a pacing cycle length of 150 msec. Patch clamp experiments performed in isolated guinea pig ventricular myocytes demonstrated that droperidol decreases the time-dependent outward K+ current elicited by short depolarizations (250 msec; I(K)250) in a concentration-dependent manner. Estimated IC50 for I(K)250, which mostly underlies I(K)r, was 28 nmol/L. Finally, HERG K+ current elicited in HEK293 cells expressing high levels of HERG protein was decreased 50% by droperidol 32.2 nmol/L. CONCLUSION Potent block of I(K)r by droperidol is likely to underlie QT prolongation observed in patients treated at therapeutic plasma concentrations (10 to 400 nmol/L) of the drug.
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Affiliation(s)
- B Drolet
- Quebec Heart Institute, Laval Hospital and Faculties of Pharmacy and Medicine, Laval University, Sainte-Foy, Québec, Canada
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Abstract
OBJECTIVES The purpose of this study was to test the hypothesis that the extent of drug-induced QT prolongation by dofetilide is greater in sinus rhythm (SR) after cardioversion compared with during atrial fibrillation (AF). BACKGROUND Anecdotes suggest that when action potential-prolonging antiarrhythmic drugs are used for AF, excessive QT prolongation and torsades de pointes (TdP) often occur shortly after sinus rhythm is restored. METHODS QT was measured in nine patients with AF who received two identical infusions of dofetilide: 1) before elective direct current cardioversion and 2) within 24 h of restoration of SR. RESULTS During AF, dofetilide did not prolong QT (baseline: 368 +/- 48 ms vs. drug: 391 +/- 60, p = NS) whereas during SR, QT was prolonged from 405 +/- 55 to 470 +/- 67 ms (p < 0.01). In four patients (group I), the SR dofetilide infusion was terminated early because QT prolonged to >500 ms, and one patient developed asymptomatic nonsustained TdP. The remaining five patients (group II) received the entire dose during SR. Although deltaQT was greater in group I during SR (91 +/- 22 vs. 45 +/- 25 ms, p < 0.05), plasma dofetilide concentrations during SR were similar in the two groups (2.72 +/- 0.96 vs. 2.77 +/- 0.25 ng/ml), and in AF (2.76 +/- 1.22 ng/ml). DeltaQT in SR correlated inversely with baseline SR heart rate (r = -0.69, p < 0.05), and QT dispersion developing during the infusion (r = 0.79, p < 0.01). CONCLUSIONS Shortly after restoration of SR, there was increased sensitivity to QT prolongation by this I(Kr)-specific blocker. Slower heart rates after cardioversion and QT dispersion during treatment appear to be important predictors of this response.
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Affiliation(s)
- A M Choy
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-6602, USA
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Houltz B, Darpö B, Edvardsson N, Blomström P, Brachmann J, Crijns HJ, Jensen SM, Svernhage E, Vallin H, Swedberg K. Electrocardiographic and clinical predictors of torsades de pointes induced by almokalant infusion in patients with chronic atrial fibrillation or flutter: a prospective study. Pacing Clin Electrophysiol 1998; 21:1044-57. [PMID: 9604236 DOI: 10.1111/j.1540-8159.1998.tb00150.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The aim of this study was to identify predictors of torsades de pointes (TdP) in patients with atrial fibrillation (AF) or flutter exposed to the Class III antiarrhythmic drug almokalant. TdP can be caused by drugs that prolong myocardial repolarization. One hundred patients received almokalant infusion during AF (infusion 1) and 62 of the patients during sinus rhythm (SR) on the following day (infusion 2). Thirty-two patients converted to SR. Six patients developed TdP. During AF, T wave alternans was more common prior to infusion (baseline) in patients developing TdP (50% vs 4%, P < 0.01). After 30 minutes of infusion 1, the TdP patients exhibited a longer QT interval (493 +/- 114 vs 443 +/- 54 ms [mean +/- SD], P < 0.01), a larger precordial QT dispersion (50 +/- 74 vs 27 +/- 26 ms, P < 0.05), and a lower T wave amplitude (0.12 +/- 0.21 vs 0.24 +/- 0.16 mV, P < 0.01). After 30 minutes of infusion 2, they exhibited a longer QT interval (672 +/- 26 vs 489 +/- 74 ms, P < 0.001), a larger QT dispersion in precordial (82 +/- 7 vs 54 +/- 52 ms, P < 0.01) and extremity leads (163 +/- 0 vs 40 +/- 34 ms, P < 0.001), and T wave alternans was more common (100% vs 0%, P < 0.001). Risk factors for development of TdP were at baseline: female gender, ventricular extrasystoles, and treatment with diuretics; and, after 30 minutes of infusion: sequential bilateral bundle branch block, ventricular extrasystoles in bigeminy, and a biphasic T wave. Patients developing TdP exhibited early during almokalant infusion a pronounced QT prolongation, increased QT dispersion, and marked morphological T wave changes.
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Affiliation(s)
- B Houltz
- Department of Medicine, Sahlgrenska University Hospital, Ostra, Göteborg, Sweden.
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Kobayashi Y, Atarashi H, Ino T, Kuruma A, Nomura A, Saitoh H, Hayakawa H. Clinical and electrophysiologic effects of dofetilide in patients with supraventricular tachyarrhythmias. J Cardiovasc Pharmacol 1997; 30:367-73. [PMID: 9300322 DOI: 10.1097/00005344-199709000-00015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The clinical and electrophysiologic effect of intravenous dofetilide was evaluated in patients with paroxysmal atrial fibrillation (AF) of recent onset (< 7 days) and paroxysmal supraventricular tachycardia (PSVT). From 2.5 to 5.0 micrograms/kg of dofetilide was administered intravenously for the termination of arrhythmias. For the electrophysiologic study (EPS), 3.0 micrograms for loading and subsequently 2 micrograms/kg was injected for 45 min as a maintenance dose. The EPSs were performed before the loading and during the maintenance dose. AF was successfully converted to sinus rhythm in seven (54%) of 13 patients. The duration of AF from its onset was significantly shorter in responders than that of nonresponders (p < 0.05). Dofetilide also terminated PSVT in four of six patients. In the EPS, dofetilide proportionately lengthened the effective refractory period of the atrium, ventricle, and the accessory pathways without slowing of the intracardiac conduction. Dofetilide completely suppressed the induction of PSVT in seven of 13 patients, restricted the induction zone in five, and inhibited perpetuation of the arrhythmia in the remaining one. The cycle length of PSVT remained unchanged after dofetilide. These results imply that the suppression of the development and maintenance of reentrant arrhythmias may result from the lengthening effect of dofetilide on the refractoriness and the consequent elimination of the excitable gap at the critical part of the reentrant loop.
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Affiliation(s)
- Y Kobayashi
- First Department of Internal Medicine, Nippon Medical School, Tokyo, Japan
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Falk RH, Pollak A, Singh SN, Friedrich T. Intravenous dofetilide, a class III antiarrhythmic agent, for the termination of sustained atrial fibrillation or flutter. Intravenous Dofetilide Investigators. J Am Coll Cardiol 1997; 29:385-90. [PMID: 9014993 DOI: 10.1016/s0735-1097(96)00506-2] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVES This study sought to determine the safety and efficacy of a single bolus of intravenous dofetilide, a pure class III antiarrhythmic agent, for the termination of sustained atrial fibrillation or flutter. BACKGROUND Dofetilide is a highly selective blocker of the rapid component of the delayed rectifier current causing action potential prolongation. These effects, and preliminary clinical data, suggest that it may be effective in the treatment of atrial fibrillation and flutter. METHODS Ninety-one patients with sustained atrial fibrillation (75 patients) or flutter (16 patients) were entered into a double-blind, randomized multicenter study of one of two doses of dofetilide (4 or 8 micrograms/kg body weight) or placebo. RESULTS Dofetilide effectively terminated the arrhythmia in 31% of patients receiving 8 micrograms/kg, a statistically significant difference from those receiving 4 micrograms/kg (conversion rate 12.5%, p < 0.05) or placebo (no conversion, p < 0.01). Patients with atrial flutter had a greater response to dofetilide (54% conversion rate) than those with atrial fibrillation (14.5% conversion rate, p < 0.001). CONCLUSIONS Intravenous dofetilide can convert sustained atrial fibrillation or flutter to sinus rhythm. However, its efficacy is greater in flutter--a response that contrasts with the poorer response seen with class I agents. This finding potentially represents an important advance in the pharmacologic termination of atrial flutter.
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Affiliation(s)
- R H Falk
- Division of Cardiology, Boston Medical Center, Massachusetts 02118, USA.
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Frost L, Mortensen PE, Tingleff J, Platou ES, Christiansen EH, Christiansen N. Efficacy and safety of dofetilide, a new class III antiarrhythmic agent, in acute termination of atrial fibrillation or flutter after coronary artery bypass surgery. Dofetilide Post-CABG Study Group. Int J Cardiol 1997; 58:135-40. [PMID: 9049678 DOI: 10.1016/s0167-5273(96)02856-2] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Ninety-eight patients, who developed atrial fibrillation/flutter after coronary artery bypass grafting within 1-6 days after surgery, were included into a double-blind, placebo-controlled, randomized trial to assess the efficacy and safety of dofetilide. Patients were randomly allocated to dofetilide 4 micrograms/kg i.v. (n = 33), dofetilide 8 micrograms/kg i.v. (n = 32) or placebo (n = 33) given intravenously over 15 min at a constant infusion rate. Responders were defined as patients who converted to sinus rhythm at any time during the initial 3 h after the start of the infusion. The conversion rates were 24% (8/33) on placebo, 36% (12/33) on dofetilide 4 micrograms/kg, and 44% (14/32) on dofetilide 8 micrograms/kg. The P-values (two-tailed) were 0.27 for dofetilide 4 micrograms/kg vs. placebo, 0.11 for dofetilide 8 micrograms/kg vs. placebo, and 0.10 for dose-response relationship. Short episodes of aberrant ventricular conduction and ventricular tachycardia were seen separately in three subjects after dofetilide 8 micrograms/kg. No episodes of torsades de pointes were noted. No negative inotropic effect was noted. In conclusion, dofetilide was well tolerated, but the effects on atrial fibrillation/flutter did not attain statistical significance, possibly due to the high placebo conversion rate.
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Affiliation(s)
- L Frost
- Department of Cardiology, Skejby Sygehus, University Hospital, Aarhus, Denmark
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Abstract
Dofetilide is more effective than quinidine to terminate atrial flutter in this animal model. It is also more capable of lengthening refractoriness more uniformly than quinidine. While the investigators describe local changes in refractoriness and dispersion of refractoriness and wavelength meticulously, it is not clear which, if any, of these properties cause flutter termination or influence reinduction. This report provides new insight into the electrophysiologic mechanisms of antiarrhythmic drugs used to treat atrial arrhythmias. Related investigations are needed to expand our knowledge of the actions of antiarrhythmic drugs, how these drugs affect critical portions of the reentrant circuit, and how to identify potential adverse effects of these agents. Application of these data may help guide the use of antiarrhythmic drugs and allow development of safer, and yet more potent, compounds. At least, it will give us pause about using more toxic and less effective drugs. While Class III drugs, specifically dofetilide, may be more potent and beneficial than quinidine in this model, it is uncertain that these results pertain to human reentrant atrial arrhythmias, particularly, atrial flutter. Perhaps dofetilide will be effective for certain types of atrial flutter requiring an anatomical center defined by an area of injury or surgical scar in the right atrium. The fact that these, and previous, data indicate a specific beneficial effect of dofetilide, particularly on atrial flutter, is interesting. Even if dofetilide proves highly effective for human atrial flutter, its safety will need to be proven in large clinical trials. The most obvious concern about dofetilide is development of serious side effects such as torsades de pointes. Clinical trials of this drug for atrial arrhythmias are presently ongoing. Ultimately, the long-term use of such a drug is dependent on the emergence of other highly effective therapies such as radiofrequency ablation.
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