Amiodarone interaction with beta-blockers: analysis of the merged EMIAT (European Myocardial Infarct Amiodarone Trial) and CAMIAT (Canadian Amiodarone Myocardial Infarction Trial) databases. The EMIAT and CAMIAT Investigators

Management of patients with an electrical storm or clustered ventricular arrhythmias: a clinical consensus statement of the European Heart Rhythm Association of the ESC-endorsed by the Asia-Pacific Heart Rhythm Society, Heart Rhythm Society, and Latin-American Heart Rhythm Society

Electrical storm (ES) is a state of electrical instability, manifesting as recurrent ventricular arrhythmias (VAs) over a short period of time (three or more episodes of sustained VA within 24 h, separated by at least 5 min, requiring termination by an intervention). The clinical presentation can vary, but ES is usually a cardiac emergency. Electrical storm mainly affects patients with structural or primary electrical heart disease, often with an implantable cardioverter-defibrillator (ICD). Management of ES requires a multi-faceted approach and the involvement of multi-disciplinary teams, but despite advanced treatment and often invasive procedures, it is associated with high morbidity and mortality. With an ageing population, longer survival of heart failure patients, and an increasing number of patients with ICD, the incidence of ES is expected to increase. This European Heart Rhythm Association clinical consensus statement focuses on pathophysiology, clinical presentation, diagnostic evaluation, and acute and long-term management of patients presenting with ES or clustered VA.

Impact of amiodarone use on metoprolol concentrations, α-OH-metoprolol concentrations, metoprolol dosing and heart rate: A cross-sectional study

Small studies suggest that amiodarone is a weak inhibitor of cytochrome P450 (CYP) 2D6. Inhibition of CYP2D6 leads to increases in concentrations of drugs metabolized by the enzyme, such as metoprolol. Considering that both metoprolol and amiodarone have β-adrenergic blocking properties and that the modest interaction between the two drugs would result in increased metoprolol concentrations, this could lead to a higher risk of bradycardia and atrioventricular block. The primary objective of this study was to evaluate whether metoprolol plasma concentrations collected at random timepoints from patients enrolled in the Montreal Heart Institute Hospital Cohort could be useful in identifying the modest pharmacokinetic interaction between amiodarone and metoprolol. We performed an analysis of a cross-sectional study, conducted as part of the Montreal Heart Institute Hospital Cohort. All participants were self-described "White" adults with metoprolol being a part of their daily pharmacotherapy regimen. Of the 999 patients being treated with metoprolol, 36 were also taking amiodarone. Amiodarone use was associated with higher metoprolol concentrations following adjustment for different covariates (p = .0132). Consistently, the association between amiodarone use and lower heart rate was apparent and significant after adjustment for all covariates under study (p = .0001). Our results highlight that single randomly collected blood samples can be leveraged to detect modest pharmacokinetic interactions.

Overview of Cardiac Arrhythmias and Treatment Strategies

Maintenance of normal cardiac rhythm requires coordinated activity of ion channels and transporters that allow well-ordered propagation of electrical impulses across the myocardium. Disruptions in this orderly process provoke cardiac arrhythmias that may be lethal in some patients. Risk of common acquired arrhythmias is increased markedly when structural heart disease caused by myocardial infarction (due to fibrotic scar formation) or left ventricular dysfunction is present. Genetic polymorphisms influence structure or excitability of the myocardial substrate, which increases vulnerability or risk of arrhythmias in patients. Similarly, genetic polymorphisms of drug-metabolizing enzymes give rise to distinct subgroups within the population that affect specific drug biotransformation reactions. Nonetheless, identification of triggers involved in initiation or maintenance of cardiac arrhythmias remains a major challenge. Herein, we provide an overview of knowledge regarding physiopathology of inherited and acquired cardiac arrhythmias along with a summary of treatments (pharmacologic or non-pharmacologic) used to limit their effect on morbidity and potential mortality. Improved understanding of molecular and cellular aspects of arrhythmogenesis and more epidemiologic studies (for a more accurate portrait of incidence and prevalence) are crucial for development of novel treatments and for management of cardiac arrhythmias and their consequences in patients, as their incidence is increasing worldwide.

Pharmacologic Management for Ventricular Arrhythmias: Overview of Anti-Arrhythmic Drugs

Ventricular arrhythmias (Vas) are a life-threatening condition and preventable cause of sudden cardiac death (SCD). With the increased utilization of implantable cardiac defibrillators (ICD), the focus of VA management has shifted toward reduction of morbidity from VAs and ICD therapies. Anti-arrhythmic drugs (AADs) can be an important adjunct therapy in the treatment of recurrent VAs. In the treatment of VAs secondary to structural heart disease, amiodarone remains the most well studied and current guideline-directed pharmacologic therapy. Beta blockers also serve as an important adjunct and are a largely underutilized medication with strong evidentiary support. In patients with defined syndromes in structurally normal hearts, AADs can offer tailored therapies in prevention of SCD and improvement in quality of life. Further clinical trials are warranted to investigate the role of newer therapeutic options and for the direct comparison of established AADs.

Dynamic High-density Functional Substrate Mapping Improves Outcomes in Ischaemic Ventricular Tachycardia Ablation: Sense Protocol Functional Substrate Mapping and Other Functional Mapping Techniques

Post-infarct-related ventricular tachycardia (VT) occurs due to reentry over surviving fibres within ventricular scar tissue. The mapping and ablation of patients in VT remains a challenge when VT is poorly tolerated and in cases in which VT is non-sustained or not inducible. Conventional substrate mapping techniques are limited by the ambiguity of substrate characterisation methods and the variety of mapping tools, which may record signals differently based on their bipolar spacing and electrode size. Real world data suggest that outcomes from VT ablation remain poor in terms of freedom from recurrent therapy using conventional techniques. Functional substrate mapping techniques, such as single extrastimulus protocol mapping, identify regions of unmasked delayed potentials, which, by nature of their dynamic and functional components, may play a critical role in sustaining VT. These methods may improve substrate mapping of VT, potentially making ablation safer and more reproducible, and thereby improving the outcomes. Further large-scale studies are needed.

Anti-arrhythmic drug therapy in implantable cardioverter-defibrillator recipients

Implantable cardioverter-defibrillators (ICDs) have revolutionized the primary and secondary prevention of patients with ventricular arrhythmias. However, the adverse effects of appropriate or inappropriate shocks may require the adjunctive use of anti-arrhythmic drugs (AADs). Beta blockers are the cornerstone of pharmacological primary and secondary prevention of ventricular arrhythmias. In addition to their established efficacy at reducing the incidence of ventricular arrhythmias, beta-blockers are safe with few side effects. Amiodarone is superior to beta blockers and sotalol for the prevention of ventricular arrhythmia recurrence. However, long-term amiodarone use is associated with significant side effects that limit its utility. Sotalol and mexiletine are the main alternatives to amiodarone with a better side effect profile though they are less efficacious at preventing ventricular arrhythmia recurrence. Dofetilide, azimilide and ranolazine are emerging as therapeutic options for secondary prevention; more studies are needed to assess efficacy and safety in comparison to currently used agents. Beta blockers and amiodarone are the mainstay of therapy in patients experiencing electrical storm; their use reduces the frequency of ventricular arrhythmias and ICD intervention as well as affording time until catheter ablation can be considered.

Effect of Empagliflozin Versus Placebo on Cardiac Sympathetic Activity in Acute Myocardial Infarction Patients with Type 2 Diabetes Mellitus: Rationale

INTRODUCTION

Protection from lethal ventricular arrhythmias leading to sudden cardiac death is one of the most important problems after myocardial infarction. Cardiac sympathetic hyperactivity is related to poor prognosis and fatal arrhythmias and can be non-invasively assessed with heart rate variability, heart rate turbulence, T-wave alternans, late potentials, and ¹²³I-meta-iodobenzylguanide (¹²³I-MIBG) scintigraphy. Sodium glucose cotransporter 2 (SGLT2) inhibitors potentially reduce sympathetic nervous system activity that is augmented in part due to the stimulatory effect of hyperglycemia. The EMBODY trial is designed to determine whether the suppression of cardiac sympathetic activity induced by the SGLT2 inhibitor is accompanied by protection against adverse cardiovascular outcomes.

METHODS

The EMBODY trial is a prospective, multicenter, randomized, double-blind, placebo-controlled trial in patients with acute MI and type 2 diabetes in Japan. A total of 98 patients will be randomized (1:1) to receive once-daily placebo or empagliflozin, an SGLT2 inhibitor, 10 mg. The primary end point is the change from baseline to 24 weeks in heart rate variability. Secondary end points include the change from baseline for other sudden cardiac death surrogate-markers such as heart rate turbulence, T-wave alternans, late potentials, and ¹²³I-MIBG scintigraphy imaging. Adverse effects will be evaluated throughout the trial period.

PLANNED OUTCOMES

The EMBODY trial will evaluate the potential cardioprotective effect of empagliflozin and will provide additional important new data regarding its preventative effects on sudden cardiac death.

TRIAL REGISTRATION

Unique Trial Number, UMIN000030158 ( https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000034442 ).

FUNDING

Nippon Boehringer Ingelheim and Eli Lilly and Company.

Ventricular arrhythmias in nonischemic cardiomyopathy

Nonischemic cardiomyopathies (NICMs) are composed of variable disease entities, including primary and secondary cardiomyopathies. Determining the etiology of NICM provides pivotal roles of not only the understanding of the individual pathogenesis, but also the clinical management, such as risk stratification, pharmacological treatment, and intervention therapies. Despite the diverse causes of NICM, these cases mostly require clinical attention owing to progressive myocardial injury, resulting in ventricular dysfunction and heart failure. The interaction between the diseased ventricular substrates and systemic/neurophysiological factors contributes to the cornerstones responsible for ventricular arrhythmogenesis and sudden cardiac death (SCD). Prevention of SCD and diminishing ventricular tachyarrhythmias are the important mainstays for the management of NICM patients. Given the understanding of the abnormal ventricular substrates and advancement of navigation systems, radiofrequency catheter ablation (RFCA) has become an adjunctive or alternative strategy for NICM patients who experience drug-refractory ventricular tachycardias (VTs). Successful ablation can frequently be achieved at the expense of an epicardial intervention. A recent study has proven the survival benefits for NICM patients who are free from recurrent VTs after a successful RFCA, regardless of the New York Heart Association (NYHA) functional class status or left ventricular ejection fraction. Additionally, recent evidence has highlighted the better delineation of a diseased myocardium through the incorporation of cardiovascular magnetic resonance imaging (CMRI) and 3D mapping systems, which can facilitate the identification of critical ventricular arrhythmogenic substrates in NICM patients.

Case Report of the Patient with Acute Myocardial Infarction: “From Flatline to Stent Implantation”

Asystole is a rare primary manifestation in the development of sudden cardiac death (SCD), and survival during cardiac arrest as the consequence of asystole is extremely low. The aim of our paper is to illustrate successful cardiopulmonary resuscitation (CPR) in patients with acute myocardial infarction (AMI) and rare and severe form of cardiac arrest - asystole. A very short time between cardiac arrest in acute myocardial infarction, which was manifested by asystole, and the adequate CPR measures that have been taken are of great importance for the survival of our patient.

After successful reanimation, the diagnosis of anterior wall AMI with ST segment elevation was established. The right therapeutic strategy is certainly the early primary percutaneous coronary intervention (PPCI). In less than two hours, after recording the “flatline” and successful reanimation, the patient was in the catheterization laboratory, where a successful PPCI of LAD was performed, after emergency coronary angiography. In the further treatment course of the patient, the majority of risk factors were corrected, except for smoking, which may be the reason for newly discovered lung tumor disease. Early recognition and properly applied treatment of CPR can produce higher rates of survival.

Effect of dronedarone on the pharmacokinetics of carvedilol following oral administration to rats

Dronedarone is a CYP2D6 inhibitor; therefore, it is prudent to exercise caution when concurrently administering CYP2D6-metabolized β-blockers because of a lack of published data on potential drug interactions. The aim of this study was to investigate the effect of dronedarone on the pharmacokinetics of orally administered carvedilol in rats. Twenty male Sprague-Dawley rats were randomly divided into two groups and 10mg/kg carvedilol was administered to the rat with or without dronedarone pretreatment in a parallel design. Blood samples were collected before and after 0.25, 0.5, 0.75, 1, 2, 4, 6, 8, 12, and 24h of drug administration. The plasma concentration of carvedilol was determined using LC-MS/MS. The systemic exposure to carvedilol was significantly increased and elimination of carvedilol was significantly decreased in the dronedarone-pretreated rats than in the vehicle-pretreated rats. The one-compartment model with first-order absorption and elimination was sufficient to explain the pharmacokinetic characters after single oral administration of carvedilol to both vehicle-pretreated and dronedarone-pretreated rats. This study suggests that dronedarone inhibits CYP2D6-mediated carvedilol metabolism, and dose adjustment is needed in carvedilol and dronedarone combination therapy. Further studies are needed to clarify the effect of dronedarone on carvedilol and CYP2D6 substrates in clinical use.

Ventricular Arrhythmia after Acute Myocardial Infarction: 'The Perfect Storm'

Ventricular tachyarrhythmias (VAs) commonly occur early in ischaemia, and remain a common cause of sudden death in acute MI. The thrombolysis and primary percutaneous coronary intervention era has resulted in the modification of the natural history of an infarct and subsequent VA. Presence of VA could independently influence mortality in patients recovering from MI. Appropriate risk assessment and subsequent treatment is warranted in these patients. The prevention and treatment of haemodynamically significant VA in the post-infarct period and of sudden cardiac death remote from the event remain areas of ongoing study.

β-Adrenergic Blockers as Antiarrhythmic and Antifibrillatory Compounds: An Overview

β-Adrenergic blockers have a wide spectrum of action for controlling cardiac arrhythmias that is larger than initially thought. Data from the past several decades indicate that, as an antiarrhythmic class, β-blockers remain among the very few pharmacologic agents that reduce the incidence of sudden cardiac death, prolong survival, and ameliorate symptoms caused by arrhythmias in patients with cardiac disease. As a class of compounds, β-blockers have a fundamental pharmacologic property that attenuates the effects of competitive adrenergic receptors. However, the net clinical effects of the different β-receptor blockers may vary quantitatively because of variations in associated intrinsic sympathomimetic agonism and in their intrinsic potency for binding to β-receptors. These individual compounds also differ in their selectivity for β1- and β2-receptors. Metoprolol is a β1-selective blocker, whereas carvedilol is a nonselective β1- and β2-blocker, an antioxidant, and has a propensity to inhibit α1-receptors and endothelin. Evolving data from controlled and uncontrolled clinical trials suggest that there are clinically significant differences among this class of drugs. Recent evidence also suggests that the antiarrhythmic actions of certain β-receptor blockers such as carvedilol and metoprolol extend beyond the ventricular tissue to encompass atrial cells and help maintain sinus rhythm in patients with atrial fibrillation, especially in combination with potent antifibrillatory agents such as amiodarone. This introduction provides a current perspective on these newer developments in the understanding of the antiarrhythmic and antifibrillatory actions of β-blockers.

Electrical Storm: Case Series and Review of Management

Electrical storm is defined as a recurrent episode of hemodynamically destabilizing ventricular tachyarrhythmia that usually requires electrical cardioversion or defibrillation. We describe three cases presenting with electrical storm under differing circumstances: (1) a 57-year-old man with ST-elevation myocardial infarction within 1 week of a posterior circulation stroke who developed refractory sustained ventricular tachycardia 10 days after an acute myocardial infarction; (2) a 65-year-old man who developed polymorphic ventncular tachycardia and ventricular fibrillation following dobutamine echocardiography; and (3) a 20-year-old woman who developed intractable ventricular fibrillation following an overdose of a weight-reduction pill. The management of electrical storm is discussed, and evolving literature supporting the routine use of intravenous amiodarone and β-blockers in place of intravenous lidocaine is critically examined.

[Electrical storm in the emergency room: clinical pathways]

In patients with structural heart disease, occurrence of an electrical storm (ES) is associated with increased mortality acutely and during medium term follow-up. Depending on the underlying heart disease and baseline type of arrhythmia, different clinical pathways have to be followed to reach sustained freedom from ventricular arrhythmia recurrences. Trigger elimination, sympathetic blockade (initially using betablockers and sedation), antiarrhythmic therapy with amiodarone and catheter ablation, treatment of heart failure and invasive hemodynamic support are cornerstones of the treatment. We present an algorithm which may help to organize an optimized treatment for each ES patient, implementing invasive treatment options like coronary angioplasty, catheter ablation and invasive circulatory support. Further studies are necessary to evaluate medium term outcome of such a structured therapy.

Optimal antiarrhythmic drug therapy for electrical storm

Electrical storm, defined as 3 or more separate episodes of ventricular tachycardia or ventricular fibrillation within 24 hours, carries significant morbidity and mortality. These unstable ventricular arrhythmias have been described with a variety of conditions including ischemic heart disease, structural heart disease, and genetic conditions. While implantable cardioverter defibrillator implantation and ablation may be indicated and required, antiarrhythmic medication remains an important adjunctive therapy for these persons.

Ventricular tachycardia in ischemic heart disease substrates

Advances in the treatment of myocardial infarction (MI) have improved survival after ischemic cardiac injury. Post-infarct structural and functional remodeling results in electrophysiologic substrates at risk for monomorphic ventricular tachycardia (MMVT). Characterization of this substrate using a variety of clinical and investigative tools has improved our understanding of MMVT circuits, and has accelerated the development of device and catheter-based therapies aimed at identification and elimination of this arrhythmia. This review will discuss the central role of the ischemic heart disease substrate in the development MMVT. Electrophysiologic characterization of the post-infarct myocardium using bipolar electrogram amplitudes to delineate scar border zones will be reviewed. Functional electrogram determinants of reentrant circuits such as isolated late potentials will be discussed. Strategies for catheter ablation of reentrant ventricular tachycardia, including structural and functional targets will also be examined, as will the role of the epicardial mapping and ablation in the management of recurrent MMVT.

Use of evidence-based cardiac prevention therapy among outpatients with atrial fibrillation

BACKGROUND

Patients with atrial fibrillation often have cardiovascular risk factors or known comorbid disease, yet the use of evidence-based primary and secondary prevention cardiac therapy among atrial fibrillation outpatients is unknown.

METHODS

Using baseline data collected between June 2010 and August 2011 from 174 sites participating in ORBIT-AF, a US national registry of patients with atrial fibrillation coordinated from Durham, NC, we examined professional guideline-recommended evidence-based therapy use for cardiovascular comorbid conditions and risk factors. Multivariable logistic regression was used to identify factors associated with receipt of all indicated evidence-based therapy.

RESULTS

Among 10,096 enrolled patients, 93.5% were eligible for one or more evidence-based therapies. Among those eligible, 46.6% received all indicated therapies: 62.3% received an antiplatelet agent, 72.3% received a beta-blocker, 59.5% received an angiotensin-converting enzyme or angiotensin receptor blocker, 15.3% received an aldosterone antagonist, 65.7% received a statin, and 58.8% received an implantable cardioverter-defibrillator. A minority of patients with coronary artery disease, diabetes mellitus, heart failure, and peripheral vascular disease received all indicated therapies (25.1%, 43.2%, 42.5%, and 43.4%, respectively). A total of 52.4% of patients had controlled hypertension and 74.6% of patients with hyperlipidemia received a statin. Factors associated with nonreceipt of all indicated therapies included frailty, comorbid illness, geographic region, and antiarrhythmic drug therapy.

CONCLUSIONS

The majority of eligible atrial fibrillation outpatients did not receive all guideline-recommended therapies for cardiovascular comorbid conditions and risk factors. This represents a potential opportunity to improve atrial fibrillation patients' quality of care and outcomes.

Current and emerging antiarrhythmic drug therapy for ventricular tachycardia

Ventricular arrhythmias, including ventricular fibrillation (VF) and sustained ventricular tachycardia (VT), are the principal causes of sudden cardiac death in patients with structural heart disease. While coronary artery disease is the predominant substrate associated with the development of VT, these arrhythmias are known to occur in a variety of disorders, including dilated cardiomyopathy, valvular and congenital heart disease, and cardiac ion channelopathies such as the long QT syndrome. In a minority of patients, VT occurs in the absence of structural heart disease. Despite the established mortality benefit of the implantable cardioverter defibrillator (ICD) in patients at risk of lethal arrhythmias, recurrent VT/VF events continue to be a source of morbidity and impaired quality of life in such patients. Antiarrhythmic therapy is indicated in select patients to treat symptomatic VT episodes, to reduce the incidence of ICD shocks, and potentially to improve quality of life and reduce hospitalizations related to cardiac arrhythmia. The primary adverse effects of antiarrhythmic medications are related to both cardiac and extracardiac toxicity, including the risk of proarrhythmia. Current drug therapy for ventricular arrhythmia has been limited by suboptimal efficacy in many patients, resulting in recurrent VT/VF events, and by drug toxicity or intolerance leading to discontinuation in a large percentage of patients. Amiodarone and sotalol are the principal agents used in the chronic treatment of VT. In addition, dronedarone and dofetilide, agents approved for the treatment of atrial fibrillation, and ranolazine, an antianginal agent, have been demonstrated to be protective against ventricular arrhythmia in small clinical studies. Finally, advances in basic electrophysiology have uncovered new molecular targets for the treatment of ventricular arrhythmia, and pharmacologic agents directed at these targets may emerge as promising VT treatments in the future. The roles of these current and emerging therapies for the treatment of VT in humans will be summarized in this review.

Symptomatic Bradycardia, Syncope, and Prolonged QTc Interval Associated with Dronedarone Therapy

Objective

To report a case of symptomatic bradycardia, prolonged QT interval, and syncope associated with dronedarone in a patient with atrial fibrillation who was maintained in sinus rhythm.

Case Summary

A 58-year-old man presented to the emergency department with a chief complaint of chest pain and “passing out.” Three months prior, dronedarone had been initiated for maintenance of sinus rhythm. An initial electrocardiogram (ECG) revealed normal sinus rhythm with a prolonged corrected QT (QTc) interval of 645 ms. Upon hospital admission, dronedarone was discontinued. Approximately 17 hours after hospitalization and 35 hours after the last ingested dronedarone dose, a repeat ECG revealed a QTc interval of 457 ms, and the patient reported symptomatic improvement. The patient was discharged home after a 3-day hospital stay without further event. The Naranjo Adverse Drug Reaction Probability Scale indicated a probable relationship between the patient's symptoms and dronedarone.

Discussion

Dronedarone is an antiarrhythmic drug that exhibits multiple mechanisms of action, including potassium, sodium, and calcium channel blockade, in addition to antiadrenegic activity. In clinical evaluations of dronedarone therapy, dronedarone was associated with a mean decrease in resting heart rate and potential to prolong the QT interval by 10 ms. These effects may result in clinically significant outcomes, as was observed in this patient.

Conclusions

This case of symptomatic bradycardia and prolonged QTc interval emphasizes the importance of monitoring the heart rate and ECG in patients prescribed dronedarone, particularly in those on concomitant drug therapy that may precipitate these events.

Drug therapy for ventricular tachyarrhythmia in heart failure

Sudden cardiac death (SCD) accounts for approximately one-third of all deaths in patients with heart failure, and is generally the result of ventricular tachycardia (VT) and/or ventricular fibrillation (VF). The mechanisms of VT/VF associated with heart failure are complex and heterogeneous; they include functional and structural remodeling, as well as neurohormonal activation. The implantable cardioverter-defibrillator is very useful for preventing SCD, but the improvement of outcome is limited in patients with cardiac dysfunction and advanced heart failure. This article reviews the current status of drug therapy for the treatment of VT/VF in patients with heart failure. Chronic beta-blocker therapy reduces SCD and improves survival. Angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers and aldosterone antagonists are thought to reduce SCD by preventing ventricular remodeling. Amiodarone is potentially effective for preventing VT/VF in patients at high risk, especially those with nonischemic heart failure. This may be a result of the complex pharmacodynamics of amiodarone, which affects many kinds of ion channels/transporters, as well as thyroid function. The pure class III antiarrhythmic drug, nifekalant, is useful in the emergency treatment of VT/VF.

Antiarrhythmic drug therapy for sustained ventricular arrhythmias complicating acute myocardial infarction

OBJECTIVE

Few data exist to guide antiarrhythmic drug therapy for sustained ventricular tachycardia/ventricular fibrillation after acute myocardial infarction. The objective of this analysis was to describe the survival of patients with sustained ventricular tachycardia/ventricular fibrillation after myocardial infarction according to antiarrhythmic drug treatment.

DESIGN AND SETTING

We conducted a retrospective analysis of ST-segment elevation myocardial infarction patients with sustained ventricular tachycardia/ventricular fibrillation in Global Use of Strategies to Open Occluded Coronary Arteries in Acute Coronary Syndromes (GUSTO) IIB and GUSTO III and compared all-cause death in patients receiving amiodarone, lidocaine, or no antiarrhythmic. We used Cox proportional-hazards modeling and inverse weighted estimators to adjust for baseline characteristics, β-blocker use, and propensity to receive antiarrhythmics. Due to nonproportional hazards for death in early follow-up (0-3 hrs after sustained ventricular tachycardia/ventricular fibrillation) compared with later follow-up (>3 hrs), we analyzed all-cause mortality using time-specific hazards.

PATIENTS AND INTERVENTIONS

Among 19,190 acute myocardial infarction patients, 1,126 (5.9%) developed sustained ventricular tachycardia/ventricular fibrillation and met the inclusion criteria. Patients received lidocaine (n = 664, 59.0%), amiodarone (n = 50, 4.4%), both (n = 110, 9.8%), or no antiarrhythmic (n = 302, 26.8%).

RESULTS

In the first 3 hrs after ventricular tachycardia/ventricular fibrillation, amiodarone (adjusted hazard ratio 0.39, 95% confidence interval 0.21-0.71) and lidocaine (adjusted hazard ratio 0.72, 95% confidence interval 0.53-0.96) were associated with a lower hazard of death-likely evidence of survivor bias. Among patients who survived 3 hrs, amiodarone was associated with increased mortality at 30 days (adjusted hazard ratio 1.71, 95% confidence interval 1.02-2.86) and 6 months (adjusted hazard ratio 1.96, 95% confidence interval 1.21-3.16), but lidocaine was not at 30 days (adjusted hazard ratio 1.19, 95% confidence interval 0.77-1.82) or 6 months (adjusted hazard ratio 1.10, 95% confidence interval 0.73-1.66).

CONCLUSION

Among patients with acute myocardial infarction complicated by sustained ventricular tachycardia/ventricular fibrillation who survive 3 hrs, amiodarone, but not lidocaine, is associated with an increased risk of death, reinforcing the need for randomized trials in this population.

Acute Antiarrhythmic Therapy of Ventricular Tachycardia and Ventricular Fibrillation

Ventricular arrhythmias (ventricular tachycardia and ventricular fibrillation) are often associated with underlying structural heart disease and require prompt assessment and treatment. Acute treatment involves initial hemodynamic stabilization of the patient followed by suppressive treatment with pharmacologic and nonpharmacologic approaches for reducing the risk of recurrence of ventricular arrhythmias and potential development of sudden cardiac death. This article reviews acute antiarrhythmic drug therapy for ventricular arrhythmias based on the clinical presentation.

Amiodarone for the treatment and prevention of ventricular fibrillation and ventricular tachycardia

Amiodarone has emerged as the leading antiarrhythmic therapy for termination and prevention of ventricular arrhythmia in different clinical settings because of its proven efficacy and safety. In patients with shock refractory out-of-hospital cardiac arrest and hemodynamically destabilizing ventricular arrhythmia, amiodarone is the most effective drug available to assist in resuscitation. Although the superiority of the transvenous implantable cardioverter defibrillator (ICD) over amiodarone has been well established in the preventive treatment of patients at high risk of life-threatening ventricular arrhythmias, amiodarone (if used with a beta-blocker) is the most effective antiarrhythmic drug to prevent ICD shocks and treat electrical storm. Both the pharmacokinetics and the electrophysiologic profile of amiodarone are complex, and its optimal and safe use requires careful patient surveillance with respect to potential adverse effects.

Adverse drug reactions in patients with cardiovascular disease

Adverse drug reactions (ADRs) occur frequently in modern medical practice, increasing morbidity and mortality and inflating the cost of care. Patients with cardiovascular disease are particularly vulnerable to ADRs due to their advanced age, polypharmacy, and the influence of heart disease on drug metabolism. The ADR potential for a particular cardiovascular drug varies with the individual, the disease being treated, and the extent of exposure to other drugs. Knowledge of this complex interplay between patient, drug, and disease is a critical component of safe and effective cardiovascular disease management. The majority of significant ADRs involving cardiovascular drugs are predictable and therefore preventable. Better patient education, avoidance of polypharmacy, and clear communication between physicians, pharmacists, and patients, particularly during the transition between the inpatient to outpatient settings, can substantially reduce ADR risk.

Amiodarone use after acute myocardial infarction complicated by heart failure and/or left ventricular dysfunction may be associated with excess mortality

BACKGROUND

We sought to assess the association of amiodarone use with mortality during consecutive periods in patients with post-acute myocardial infarction with left ventricular systolic dysfunction and/or HF treated with a contemporary medical regimen.

METHODS

This study used data from VALIANT, a randomized comparison of valsartan, captopril, or both in patients with acute myocardial infarction with HF and/or left ventricular systolic dysfunction. We compared baseline characteristics of 825 patients treated with amiodarone at randomization with 13,875 patients not treated with amiodarone. Using Cox models, we examined the association of amiodarone use with subsequent mortality during consecutive periods after randomization (days 1-16, 17-45, 46-198, and 199-1096).

RESULTS

Patients treated with amiodarone were older, had higher Killip class, and were more likely to have a history of diabetes mellitus and hypertension. Adjusting for baseline predictors of mortality, we found that amiodarone use was associated with a significant increase in mortality during 3 of the 4 periods: hazard ratio 1.5, 95% CI (1.1-2.0), P = .02, for days 1 to 16; 2.1 (1.5-2.9), P < .001, for days 17 to 45; 1.1 (0.83-1.46), P = .51, for days 46 to 198; and 1.4 (1.2-1.6), P < .001, for days 199 to 1096.

CONCLUSION

In this study, amiodarone use was associated with excess early and late all-cause and cardiovascular mortality. These observational findings are in contrast to earlier randomized trials of amiodarone and need to be validated prospectively.

Adjunctive therapy for recurrent ventricular tachycardia in patients with implantable cardioverter defibrillators

Implantable cardioverter defibrillators (ICDs) are now the mainstay of therapy in patients with sustained ventricular tachycardia (VT), ventricular fibrillation, resuscitated sudden cardiac death, or certain high-risk markers for these arrhythmic events. Although ICDs in such patients can be life-saving, they can impair quality of life when painful or frequent discharges occur or when residual VT symptoms recur prior to delivery of ICD therapies. As such, antiarrhythmic drugs often are employed in an attempt to reduce the triggering tachyarrhythmic events. Recently, studies with beta-blockers, sotalol, amiodarone, and the investigational agent azimilide have been performed to objectify the efficacy, benefits, or risks of such therapies when administered to patients with ICDs. This review describes the considerations important to the use of these therapies in ICD patients and the results and applicability of these investigative studies.

Treatment of Ventricular Dysrhythmias and Sudden Cardiac Death: A Guideline-Based Approach for Patients With Chronic Left Ventricular Dysfunction

With the rise in the use of device therapy implants, we are better identifying appropriate chronic heart failure patients for primary implantable defibrillator therapy who are at risk of ventricular arrhythmia. As our knowledge expands, however, controversial issues emerge. Guidelines have been endorsed by the major international societies, such as the American College of Cardiology (ACC), the American Heart Association (AHA), and the European Society of Cardiology. In view of certain variances in recommendations and new data, a recent joint guideline statement has been issued from these 3 societies regarding management of ventricular arrhythmia and preventing sudden cardiac death in patients with left ventricular dysfunction and heart failure. In this review, the recent joint statement is compared with those from the Heart Failure Society of America (Heart Failure Practice Guidelines 2006) and ACC/AHA (Heart Failure Guidelines 2005), with a special emphasis on new expanded criteria for primary prevention in both ischemic and nonischemic heart disease. In addition, the authors review current guidelines for electrophysiology testing in chronic left ventricular dysfunction and the emerging role of microvolt T-wave alternans as a means of risk stratification.

The Safety of Amiodarone in Patients With Heart Failure

BACKGROUND

Uncertainty persists about the safety and efficacy of amiodarone for the management of heart failure.

METHODS AND RESULTS

We randomized 3029 patients with chronic heart failure to receive carvedilol or metoprolol and followed patients for a median of 58 months. One hundred fifty-five of 1466 patients in New York Heart Association (NYHA) Class II and 209 of 1563 in Class III or IV received amiodarone at baseline. Persistence with amiodarone treatment was high and 66% received amiodarone after 4 years. During follow-up, 38.7% and 58.9% of patients receiving amiodarone in NYHA Classes II and III + IV died versus 26.2% and 43.3% not receiving amiodarone (P < .001). This difference was maintained in multivariable analysis (hazard ratio [HR] 1.5, 95% confidence interval [CI] 1.2-1.7, P < .001). The difference was explained by an increased risk of death due to circulatory failure (HR 2.4, CI 1.9-3.1, P < .001) in patients receiving amiodarone. Sudden death was not different (HR 1.07, CI 0.8-1.4, P = .7). The increased risk was similar across NYHA classes with HR of 1.60 (CI 1.2-2.1, P < .001) in NYHA Class II versus 1.58 (CI 1.3-1.9, P < .001) in Classes III + IV.

CONCLUSIONS

Treatment with amiodarone was associated with an increased risk of death from circulatory failure independent of functional class.

Dose-dependent effects of oral dronedarone on the circadian variation of RR and QT intervals in healthy subjects: implications for antiarrhythmic actions

Dronedarone, a non-iodinated benzofuran derivative, was developed as a potentially less toxic alternative to amiodarone. This study describes Holter data of dronedarone in humans. Five groups of healthy subjects were given 1 of 5 oral doses of dronedarone in a twice-daily regimen or placebo. Holter recordings of circadian rhythmicity of RR and QT intervals were evaluated. Dronedarone prolonged RR and QT intervals as a function of dose, without effect on circadian patterns. The relative prolongation of QT, QTc, and RR by dronedarone was significant. The QTc interval did not exhibit a clearly recognizable circadian pattern, suggesting that the circadian pattern of the QT interval was mostly a reflection of circadian changes in the RR interval in the study population. Dronedarone resembled amiodarone in class III and sympatholytic effects, indicating its potential as a unique antiarrhythmic compound seemingly devoid of the side effects mediated by iodine in amiodarone.