Post-myocardial infarction mortality in patients with ventricular premature depolarizations. Canadian Amiodarone Myocardial Infarction Arrhythmia Trial Pilot Study

Neurological complications of cardiovascular drugs

Cardiovascular drugs are used to treat arterial hypertension, hyperlipidemia, arrhythmias, heart failure, and coronary artery disease. They also include antiplatelet and anticoagulant drugs that are essential for prevention of cardiogenic embolism. Most neurologic complications of the cardiovascular drugs are minor or transient and are far outweighed by the anticipated benefits of treatment. Other neurologic complications are more serious and require early recognition and management. Overtreatment of arterial hypertension may cause lightheadedness or fatigue but often responds readily to dose adjustment or an alternative drug. Other drug complications may be more troublesome as in myalgia associated with statins or headache associated with vasodilators. The recognized bleeding risk of the antithrombotics requires careful calculation of risk/benefit ratios for individual patients. Many neurologic complications of cardiovascular drugs are well documented in clinical trials with known frequency and severity, but others are rare and recognized only in isolated case reports or small case series. This chapter draws on both sources to report the adverse effects on muscle, nerve, and brain associated with commonly used cardiovascular drugs.

Amiodarone versus other pharmacological interventions for prevention of sudden cardiac death

BACKGROUND

Sudden cardiac death (SCD) is one of the main causes of cardiac death. There are two main strategies to prevent it: managing cardiovascular risk factors and reducing the risk of ventricular arrhythmias. Implantable cardiac defibrillators (ICDs) constitute the standard therapy for both primary and secondary prevention; however, they are not widely available in settings with limited resources. The antiarrhythmic amiodarone has been proposed as an alternative to ICD.

OBJECTIVES

To evaluate the effectiveness of amiodarone for primary or secondary prevention in SCD compared with placebo or no intervention or any other antiarrhythmic drugs in participants at high risk (primary prevention) or who have recovered from a cardiac arrest or a syncope due to Ventricular Tachycardia/Ventricular Fibrillation, or VT/VF (secondary prevention).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (OVID), EMBASE (OVID), CINAHL (EBSCO) and LILACS on 26 March 2015. We reviewed reference lists of included studies and selected reviews on the topic, contacted authors of included studies, screened relevant meetings and searched in registers for ongoing trials. We applied no language restrictions.

SELECTION CRITERIA

Randomised and quasi-randomised trials assessing the efficacy of amiodarone versus placebo, no intervention, or other antiarrhythmics in adults. For primary prevention we considered participants at high risk for SCD. For secondary prevention we considered participants recovered from cardiac arrest or syncope due to ventricular arrhythmias.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the trials for inclusion and extracted relevant data. We contacted trial authors for missing data. We performed meta-analyses using a random-effects model. We calculated risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CIs). Three studies included more than one comparison.

MAIN RESULTS

We included 24 studies (9,997 participants). Seventeen studies evaluated amiodarone for primary prevention and six for secondary prevention. Only three studies used an ICD concomitantly with amiodarone for the comparison (all of them for secondary prevention).For primary prevention, amiodarone compared to placebo or no intervention (17 studies, 8383 participants) reduced SCD (RR 0.76; 95% CI 0.66 to 0.88), cardiac mortality (RR 0.86; 95% CI 0.77 to 0.96) and all-cause mortality (RR 0.88; 95% CI 0.78 to 1.00). The quality of the evidence was low.Compared to other antiarrhythmics (three studies, 540 participants), amiodarone reduced SCD (RR 0.44; 95% CI 0.19 to 1.00), cardiac mortality (RR 0.41; 95% CI 0.20 to 0.86) and all-cause mortality (RR 0.37; 95% CI 0.18 to 0.76). The quality of the evidence was moderate.For secondary prevention, amiodarone compared to placebo or no intervention (two studies, 440 participants) appeared to increase the risk of SCD (RR 4.32; 95% CI 0.87 to 21.49) and all-cause mortality (RR 3.05; 1.33 to 7.01). However, the quality of the evidence was very low. Compared to other antiarrhythmics (four studies, 839 participants) amiodarone appeared to increase the risk of SCD (RR 1.40; 95% CI 0.56 to 3.52; very low quality of evidence), but there was no effect in all-cause mortality (RR 1.03; 95% CI 0.75 to 1.42; low quality evidence).Amiodarone was associated with an increase in pulmonary and thyroid adverse events.

AUTHORS' CONCLUSIONS

There is low to moderate quality evidence that amiodarone reduces SCD, cardiac and all-cause mortality when compared to placebo or no intervention for primary prevention, and its effects are superior to other antiarrhythmics.It is uncertain if amiodarone reduces or increases SCD and mortality for secondary prevention because the quality of the evidence was very low.

Biologically improved nanofibrous scaffolds for cardiac tissue engineering

Nanofibrous structure developed by electrospinning technology provides attractive extracellular matrix conditions for the anchorage, migration and differentiation of stem cells, including those responsible for regenerative medicine. Recently, biocomposite nanofibers consisting of two or more polymeric blends are electrospun more tidily in order to obtain scaffolds with desired functional and mechanical properties depending on their applications. The study focuses on one such an attempt of using copolymer Poly(l-lactic acid)-co-poly (ε-caprolactone) (PLACL), silk fibroin (SF) and Aloe Vera (AV) for fabricating biocomposite nanofibrous scaffolds for cardiac tissue engineering. SEM micrographs of fabricated electrospun PLACL, PLACL/SF and PLACL/SF/AV nanofibrous scaffolds are porous, beadless, uniform nanofibers with interconnected pores and obtained fibre diameter in the range of 459 ± 22 nm, 202 ± 12 nm and 188 ± 16 nm respectively. PLACL, PLACL/SF and PLACL/SF/AV electrospun mats obtained at room temperature with an elastic modulus of 14.1 ± 0.7, 9.96 ± 2.5 and 7.0 ± 0.9 MPa respectively. PLACL/SF/AV nanofibers have more desirable properties to act as flexible cell supporting scaffolds compared to PLACL for the repair of myocardial infarction (MI). The PLACL/SF and PLACL/SF/AV nanofibers had a contact angle of 51 ± 12° compared to that of 133 ± 15° of PLACL alone. Cardiac cell proliferation was increased by 21% in PLACL/SF/AV nanofibers compared to PLACL by day 6 and further increased to 42% by day 9. Confocal analysis for cardiac expression proteins myosin and connexin 43 was observed better by day 9 compared to all other nanofibrous scaffolds. The results proved that the fabricated PLACL/SF/AV nanofibrous scaffolds have good potentiality for the regeneration of infarcted myocardium in cardiac tissue engineering.

Nonsustained ventricular tachycardia

Nonsustained ventricular tachycardia (NSVT) has been recorded in a wide range of conditions, from apparently healthy individuals to patients with significant heart disease. In the absence of heart disease, the prognostic significance of NSVT is debatable. When detected during exercise, and especially at recovery, NSVT indicates increased cardiovascular mortality within the next decades. In trained athletes, NSVT is considered benign when suppressed by exercise. In patients with non-ST-segment elevation acute coronary syndrome, NSVT occurring beyond 48 h after admission indicates an increased risk of cardiac and sudden death, especially when associated with myocardial ischemia. In acute myocardial infarction, in-hospital NSVT has an adverse prognostic significance when detected beyond the first 13 to 24 h. In patients with prior myocardial infarction treated with reperfusion and beta-blockers, NSVT is not an independent predictor of long-term mortality when other covariates such as left ventricular ejection fraction are taken into account. In patients with hypertrophic cardiomyopathy, and most probably genetic channelopathies, NSVT carries prognostic significance, whereas its independent prognostic ability in ischemic heart failure and dilated cardiomyopathy has not been established. The management of patients with NSVT is aimed at treating the underlying heart disease.

Examining the safety of amiodarone

INTRODUCTION

Amiodarone is the most widely used antiarrhythmic agent, with demonstrated effectiveness against all the spectrum of cardiac tachyarrhythmias. The risk of adverse effects acts as a limiting factor to its utilization especially in the long term. This article systematically reviews the published evidence on amiodarone versus placebo to examine its safety as an antiarrhythmic drug.

AREAS COVERED

Authors collected data on adverse effects reported in 49 randomized placebo-controlled trials with amiodarone. Adverse effects were classified according to the organ/system involved. Pooled estimates of the number needed to treat (NNT) and to harm (NNH) versus placebo were calculated.

EXPERT OPINION

Amiodarone is effective for both the acute conversion of atrial fibrillation (AF) (11 trials, NNT = 4 at 24 h; p = 0.003) and the prevention of postoperative AF (18 trials, NNT = 8; p < 0.001), although with an increased risk of bradycardia, hypotension, nausea or phlebitis (pooled NNH = 4; p < 0.001). Amiodarone administration for the maintenance of sinus rhythm has a favorable net clinical benefit (pooled NNT = 3; p < 0.001 versus pooled NNH for either thyroid toxicity, gastrointestinal discomfort, skin toxicity or eye toxicity = 11; p < 0.001). Treatment with amiodarone for the prophylaxis of sudden cardiac death has less favorable net clinical benefit (15 trials, NNT = 38; p < 0.001 versus NNH for either thyroid toxicity, hepatic toxicity, pulmonary toxicity or bradycardia = 14; p < 0.001). Amiodarone treatment in this setting should be used in only selected cases.

Delayed and indirect effects of antiarrhythmic drugs in reducing sudden cardiac death

In the USA, two-thirds of sudden cardiac deaths (SCDs) are caused by sustained ventricular tachycardia and ventricular fibrillation. Implantable cardioverter defibrillator (ICD) therapy has been demonstrated to decrease mortality caused by these arrhythmias, when used both for primary and secondary prevention. However, ICD use is expensive, has proarrhythmic effects and does not prevent ventricular arrhythmias. Antiarrhythmic drugs (AADs) can be used for acute or chronic therapy to prevent ventricular arrhythmias and SCD. Most commonly, AADs are often used in patients with an ICD who have recurrent ICD shocks due to ventricular arrhythmias. Class I AADs are used in patients with a structurally normal heart and are contraindicated in patients with structural heart disease. β-blockers have been demonstrated to be beneficial in preventing mortality and malignant tachyarrhythmias in postmyocardial infarction and congestive heart failure patients, and in patients who have an ICD. Amiodarone has a neutral effect on mortality, while other class III drugs may increase mortality in certain subgroups of patients. Dronedarone, a new class III drug, may reduce mortality, but sufficient data are not available to allow for its use in the prevention of malignant tachyarrhythmias. Few drugs that are not classified as AADs can also prevent arrhythmias, via their beneficial effects on cardiovascular remodeling. These non-ADDs have delayed and indirect effects, which are mediated by the renin-angiotensin-aldosterone system and lipid metabolism - n-3 polyunsaturated fatty acids (fish oil), and statins, and can thus can reduce the likelihood of future malignant ventricular arrhythmias in patients with coronary artery disease or congestive heart failure. The role of chronic drug therapy alone for primary and secondary prevention of SCD is less than desirable because of proarrhythmic and adverse side effects. The non-ADDs are well tolerated and have no proarrhythmic actions, thus their benefit could outweigh risks, although currently there are no concrete data to suggest this.

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.

Pro-arrhythmic effects of amiodarone and concomitant rate-control medication

AIMS

Amiodarone is one of the most efficient and safe antiarrhythmic drugs in the treatment of atrial fibrillation (AF). Although pro-arrhythmic effects of amiodarone therapy are rare, the aim of the present study was to identify clinical constellations which may lead to amiodarone-associated pro-arrhythmia.

METHODS AND RESULTS

Sixty-three consecutive patients (pts) (49 males; 64+/-10.3 years; 35 with coronary heart disease, 17 with lone AF) were retrospectively included in this study. All received an oral (92.1%) or i.v. (7.9%) loading dose of amiodarone for the treatment of AF. Cardiac diseases, concomitant medical treatment, and incidence of pro-arrhythmic effects were analysed. Three pts (4.8% of the total population) developed a clinical relevant, polymorphic ventricular tachyarrhythmia, 3-48 h after initiation of amiodarone loading. Coronary heart disease was present in all of these pts, and in two of them left ventricular ejection fraction was severely reduced. The mean QTc in these pts was only slightly prolonged; mean heart rate was significantly decreased compared with the total study population (61.0+/-7.5 vs. 74.5+/-24.1 bpm; P < or = 0.05). In all pts with pro-arrhythmia, amiodarone (two pts i.v., one patient oral) was initiated during concomitant beta-blocker/digitalis therapy. Twenty-five per cent of the patients receiving this 'triple' therapy developed ventricular arrhythmia.

CONCLUSION

The present study implies that initiation of amiodarone therapy in pts with structural heart disease and AF that are concomitantly treated with beta-blockers and digitalis may have an increased risk of amiodarone-associated pro-arrhythmia.

The International Liaison Committee on Resuscitation (ILCOR) consensus on science with treatment recommendations for pediatric and neonatal patients: pediatric basic and advanced life support

This publication contains the pediatric and neonatal sections of the 2005 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations (COSTR). The consensus process that produced this document was sponsored by the International Liaison Committee on Resuscitation (ILCOR). ILCOR was formed in 1993 and consists of representatives of resuscitation councils from all over the world. Its mission is to identify and review international science and knowledge relevant to cardiopulmonary resuscitation (CPR) and emergency cardiovascular care (ECC) and to generate consensus on treatment recommendations. ECC includes all responses necessary to treat life-threatening cardiovascular and respiratory events. The COSTR document presents international consensus statements on the science of resuscitation. ILCOR member organizations are each publishing resuscitation guidelines that are consistent with the science in this consensus document, but they also take into consideration geographic, economic, and system differences in practice and the regional availability of medical devices and drugs. The American Heart Association (AHA) pediatric and the American Academy of Pediatrics/AHA neonatal sections of the resuscitation guidelines are reprinted in this issue of Pediatrics (see pages e978-e988). The 2005 evidence evaluation process began shortly after publication of the 2000 International Guidelines for CPR and ECC. The process included topic identification, expert topic review, discussion and debate at 6 international meetings, further review, and debate within ILCOR member organizations and ultimate approval by the member organizations, an Editorial Board, and peer reviewers. The complete COSTR document was published simultaneously in Circulation (International Liaison Committee on Resuscitation. 2005 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2005;112(suppl):73-90) and Resuscitation (International Liaison Committee on Resuscitation. 2005 International Consensus Conference on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Resuscitation. 2005;67:271-291). Readers are encouraged to review the 2005 COSTR document in its entirety. It can be accessed through the CPR and ECC link at the AHA Web site: www.americanheart.org. The complete publication represents the largest evaluation of resuscitation literature ever published and contains electronic links to more detailed information about the international collaborative process. To organize the evidence evaluation, ILCOR representatives established 6 task forces: basic life support, advanced life support, acute coronary syndromes, pediatric life support, neonatal life support, and an interdisciplinary task force to consider overlapping topics such as educational issues. The AHA established additional task forces on stroke and, in collaboration with the American Red Cross, a task force on first aid. Each task force identified topics requiring evaluation and appointed international experts to review them. A detailed worksheet template was created to help the experts document their literature review, evaluate studies, determine levels of evidence, develop treatment recommendations, and disclose conflicts of interest. Two evidence evaluation experts reviewed all worksheets and assisted the worksheet reviewers to ensure that the worksheets met a consistently high standard. A total of 281 experts completed 403 worksheets on 275 topics, reviewing more than 22000 published studies. In December 2004 the evidence review and summary portions of the evidence evaluation worksheets, with worksheet author conflict of interest statements, were posted on the Internet at www.C2005.org, where readers can continue to access them. Journal advertisements and e-mails invited public comment. Two hundred forty-nine worksheet authors (141 from the United States and 108 from 17 other countries) and additional invited experts and reviewers attended the 2005 International Consensus Conference for presentation, discussion, and debate of the evidence. All 380 participants at the conference received electronic copies of the worksheets. Internet access was available to all conference participants during the conference to facilitate real-time verification of the literature. Expert reviewers presented topics in plenary, concurrent, and poster conference sessions with strict adherence to a novel and rigorous conflict of interest process. Presenters and participants then debated the evidence, conclusions, and draft summary statements. Wording of science statements and treatment recommendations was refined after further review by ILCOR member organizations and the international editorial board. This format ensured that the final document represented a truly international consensus process. The COSTR manuscript was ultimately approved by all ILCOR member organizations and by an international editorial board. The AHA Science Advisory and Coordinating Committee and the editor of Circulation obtained peer reviews of this document before it was accepted for publication. The most important changes in recommendations for pediatric resuscitation since the last ILCOR review in 2000 include: Increased emphasis on performing high quality CPR: "Push hard, push fast, minimize interruptions of chest compression; allow full chest recoil, and don't provide excessive ventilation" Recommended chest compression-ventilation ratio: For lone rescuers with victims of all ages: 30:2 For health care providers performing 2-rescuer CPR for infants and children: 15:2 (except 3:1 for neonates) Either a 2- or 1-hand technique is acceptable for chest compressions in children Use of 1 shock followed by immediate CPR is recommended for each defibrillation attempt, instead of 3 stacked shocks Biphasic shocks with an automated external defibrillator (AED) are acceptable for children 1 year of age. Attenuated shocks using child cables or activation of a key or switch are recommended in children <8 years old. Routine use of high-dose intravenous (IV) epinephrine is no longer recommended. Intravascular (IV and intraosseous) route of drug administration is preferred to the endotracheal route. Cuffed endotracheal tubes can be used in infants and children provided correct tube size and cuff inflation pressure are used. Exhaled CO2 detection is recommended for confirmation of endotracheal tube placement. Consider induced hypothermia for 12 to 24 hours in patients who remain comatose following resuscitation. Some of the most important changes in recommendations for neonatal resuscitation since the last ILCOR review in 2000 include less emphasis on using 100% oxygen when initiating resuscitation, de-emphasis of the need for routine intrapartum oropharyngeal and nasopharyngeal suctioning for infants born to mothers with meconium staining of amniotic fluid, proven value of occlusive wrapping of very low birth weight infants <28 weeks' gestation to reduce heat loss, preference for the IV versus the endotracheal route for epinephrine, and an increased emphasis on parental autonomy at the threshold of viability. The scientific evidence supporting these recommendations is summarized in the neonatal document (see pages e978-e988).

Risk stratification for arrhythmic death after myocardial infarction: Current perspective and future direction

The number of patients eligible for implantable cardioverter defibrillator implantation is large and growing. Results of the Multicenter Automatic Defibrillator Implantation Trial-II, Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure trial, and Sudden Cardiac Death in Heart Failure Trial will have a major impact on health care expenditure and economics in all countries. Therefore, one of the most important challenges in today's cardiology is finding more specific and accurate risk stratification strategies (rather than simply ejection fraction) for primary prevention of sudden cardiac death in patients who have suffered myocardial infarction. We hereby reviewed the existing data on potential risk stratifiers and assessed their impact on every day decision making and patient selection for ICD implantation.

Device based treatment of heart failure

As the population ages and survival from ischaemic heart disease improves, the incidence and prevalence of congestive cardiac failure has increased dramatically. Medical treatments including ACE inhibitors, beta blockers, and aldosterone antagonists have improved the outlook for most patients. However, despite optimal medical treatment there is a significant group of patients who continue to suffer poor morbidity and mortality. Device based treatment consisting of implantable cardioverter defibrillators (ICD) and cardiac resynchronisation therapy (CRT) devices offer new modes of treatment to patients with symptomatic heart failure despite optimal medical therapy. ICDs have been shown to reduce mortality in patients with severe heart failure while CRT leads to an improvement in functional class, quality of life scores, physiological measures such as peak Vo(2), and reduce hospitalisations. Combination devices, which provide both ICD and CRT functions, have now been seen to provide synergistic benefits in selected patients.

Can Amiodarone Prevent Sudden Cardiac Death in Patients with Hemodynamically Tolerated Sustained Ventricular Tachycardia and Coronary Artery Disease?

One of the most important challenges in today's cardiology is prevention of sudden cardiac death in high risk patients with coronary artery disease (CAD). Sustained hemodynamically tolerated ventricular tachycardia (HTVT) comprises up to 30% of all cases of monomorphic ventricular tachycardia in patients with CAD. While there is a consensus on treatment of hemodynamically unstable sustained ventricular tachycardia in patients with CAD, some controversies regarding the proper treatment of HTVT exist. We re-examined existing clinical evidence, controversies and current guidelines on the treatment of HTVT in patients with CAD and demonstrated that compared to implantable cardioverter-defibrillator, amiodarone is not an acceptable therapeutic option in patients with ischemic heart disease who suffer from HTVT.

A comparison of three different sources of data in assessing the frequencies of adverse reactions to amiodarone

AIMS

To compare the frequencies of adverse drug reactions (ADRs) to amiodarone from three separate datasets: (i) a meta-analysis of clinical trials, (ii) spontaneous reports published in medical journals, and (iii) spontaneous reports sent to the World Health Organization (WHO).

METHODS

We classified the ADRs into eight categories, based on the site involved, and built a rank order of the ADRs by category (from most to least commonly reported) for each dataset. We also calculated the relative proportions for all eight ADR categories within each dataset, in order to be able to compare the distributions of ADR frequencies: we assigned an index value of 1.0 to the frequency of respiratory toxicity in each set and calculated values for the other ADRs relative to respiratory toxicity.

RESULTS

Thyroid disorders were the most commonly reported ADRs in the WHO dataset. In contrast, published case reports showed a preponderance of respiratory disorders, while in the meta-analysis cardiac conduction problems were the most frequent. The rank orders of ADRs differed among the three datasets, as did the index values of specific ADR categories with respect to the respiratory category.

CONCLUSIONS

The distributions of ADR rank order and relative frequencies are dissimilar among the three datasets, as each dataset compiles information in a different way. Nevertheless, each dataset has its own specific strengths, and all three should be used together in obtaining a complete picture of a drug's safety profile. Important therapeutic and regulatory decisions should not simply be based on one source of data.

Diminishing proportional risk of sudden death with advancing age: implications for prevention of sudden death

BACKGROUND

Advances in primary and secondary prevention of sudden death have led to a wide array of potentially beneficial therapies. Identification of patients most likely to benefit would be of use when considering costly interventions such as an implantable defibrillator. We sought to determine the effect of advancing age on the mode of death in the Amiodarone Trialists Metanalysis.

METHODS AND RESULTS

Patients (n = 6252; age, 61.2+/-10.5 years; 83% men) were included in an analysis of predictors of sudden death (SD) and all-cause death (ACD), based on baseline variables at enrollment. Patients were divided into 5 age groups: < or =50 years, 51 to 60 years, 61 to 70 years, 71 to 80 years, and >80 years. During a mean of 16.8+/-10.3 months of follow-up, there were 1023 deaths, with an annual overall mortality rate of 11.7%. Both sudden death and nonsudden death rates increased with age, although the increase of nonsudden death with age was more dramatic. The overall proportion of death that was sudden (SD/ACD ratio) was 0.41, falling from 0.51 before age 50 years to 0.26 after age 80 years (P =.002 for trend). The SD/ACD ratio was not affected by sex, New York Heart Association Class, or left ventricular ejection fraction.

CONCLUSIONS

Although the incidence of sudden death increases with age, the proportion of death that is sudden diminishes markedly. This finding may influence the yield of interventions targeted at prevention of sudden death.

Congestive heart failure induced by the combination of atrial fibrillation and tricuspid regurgitation

Atrial fibrillation (AF) and tricuspid regurgitation (TR) may induce congestive heart failure (CHD). Using electrocardiography and echocardiography, we examined the clinical characteristics and haemodynamic findings in 100 patients with AF + TR + CHF, AF + TR, AF or TR. The fractional shortening in all groups with AF was significantly decreased compared with the TR group. The ejection fraction in patients with AF + TR + CHF was significantly lower than in the TR group. Twenty-four of the 72 patients with AF and TR (with or without CHF) were treated, and 13 were monitored for heart rate and severity of TR. Eight months after start of treatment the heart rate and typical symptoms and signs of heart failure had improved significantly in nine patients, but the severity of TR did not change. TR worsened in the remaining four patients but they did not develop CHF. Our results suggest that increased heart rate due to the combination of AF and TR could be responsible for CHF.

Visual functions and adverse ocular effects in patients with amiodarone medication

PURPOSE

To study visual functions and ocular adverse effects of long-term amiodarone medication.

METHODS

We performed an eye examination of 22 patients with long-term amiodarone medication. In addition to corrected visual acuity, colour vision was studied with the Standard Pseudoisochromatic Plates part 2 and Farnsworth-Munself 100 hue test. Contrast sensitivity was examined with the Pelli-Robson chart. Visual fields were tested by Goldmann and Friedmann perimetry.

RESULTS

Two patients with otherwise healthy eyes had abnormal blue colour vision test results. Otherwise colour vision, contrast sensitivity, and visual field test results were within normal range or could be explained by eye diseases such as cataract. Corneal drug deposits were found in 100% of the examined eyes. Slight anterior subcapsular lens opacities were found in 22.2%. Dry eyes were diagnosed in 9.1%. The eye fundi did not reveal any abnormalities that could be thought of as caused by amiodarone.

CONCLUSION

The slight blue colour vision defect found in two patients with otherwise healthy eyes might represent an early sign of the optic nerve impairment which is a rare complication of amiodarone medication. The number of corneal and lens changes as well as dry eyes were found at levels previously described.

Current utilization trends for beta-blockers in cardiovascular disease

Beta blockers have repeatedly demonstrated their therapeutic value in the treatment of a variety of diseases; as a result, multiple treatment guidelines advocate the use of beta blockers. Despite these guidelines, the use of beta blockers is remarkably low. Numerous factors that influence the trends of drug use include pharmaceutical advertisements, physician legal concerns, marketing influences, outdated therapeutic contraindications, and patient and physician demographics. Recent primary evidence from randomized clinical trials has demonstrated a significant benefit to patients with heart failure when beta-blocker therapy is added to standard therapy. To ensure proper treatment, continuing efforts must be made to provide patients with appropriate therapy that is proven to reduce the risks of mortality and morbidity.

E 047/1: a new class III antiarrhythmic agent

The efficacy, pharmacokinetics, safety, and tolerability of E 047/1, an amiodarone derivative, were evaluated in patients with acute supraventricular or ventricular arrhythmia. In an open, nonrandomized prospective multicenter trial, 20 patients were treated with three different i.v. dosage regimens of E 047/1. Arrhythmia termination indicated efficacy. Pharmacokinetics were determined by measurements of drug plasma levels. Safety was judged by changes of blood pressure, heart rate, ECG parameters, and appearance of adverse events. For local tolerability, effects at the site of infusion were assessed. In patients with atrial fibrillation and/or atrial flutter, drug plasma levels and prolongation of QT interval were correlated with efficacy. In 10 (50%) patients, therapeutic intervention with E 047/1 was successful. Drug plasma levels rapidly decreased within 1 h after administration. Blood pressure values and ECG parameters stayed constant during the observation period. Proarrhythmic effects were not observed. As adverse events, vertigo, vomiting, and nausea in three (15%) and hypotension in one (5%) patient, respectively, occurred in the high-dose bolus regimen only. At the site of infusion, no adverse effects were found. No dependency between drug plasma levels and arrhythmia termination was found. E 047/1 has proven to be efficient and safe in the treatment of arrhythmia. E 047/1 is characterized by rapid plasma elimination, absence of proarrhythmic or cardiodepressive effects, mild adverse events, and excellent local tolerability. For further investigation, we recommend a combined bolus- and weight-adapted infusion regimen.

Meta-analysis of antiarrhythmic drug trials

During the past 15 years, the efficacy of antiarrhythmic drugs has been investigated for reducing premature death in patients at high risk of arrhythmia. Whereas the benefits of beta-blocker therapy are well established, a reduction in mortality with other antiarrhythmic drugs remains unproved and in some cases, there is evidence of increased mortality with class I and some class III agents. A limitation of individual clinical trials is inadequate sample size to detect significant differences between interventions. Meta-analysis, by combining results from multiple clinical trials, provides a technique to overcome sample size limitations and assess the benefits and limitations of an intervention. Thirteen randomized clinical trials evaluated the role of prophylactic amiodarone in patients at risk of death from cardiac arrhythmias. Whereas 3 of these studies reported a reduction in mortality, several others revealed no benefits of amiodarone. Because neither trial was designed to detect reductions in total mortality, it remained unclear whether the beneficial effect of amiodarone on arrhythmic death and resuscitated ventricular fibrillation translated into a beneficial effect on total mortality. To address this, a meta-analysis was performed from the 13 trials of amiodarone in patients after an acute myocardial infarction or with congestive heart failure. The results showed a significant reduction in mortality and in arrhythmic death with amiodarone.

Management of ventricular arrhythmias: a trial-based approach

Sudden cardiac death accounts for approximately 300,000 deaths annually in the U.S., and most of these are secondary to ventricular tachycardia (VT) and fibrillation in patients with coronary artery disease. Most patients with cardiac death die before reaching the hospital, which brought about a tremendous amount of research focused at identifying patients at high risk. Several trials were initiated to test the effectiveness of various therapeutic measures in these high-risk patients. A history of myocardial infarction, depressed left ventricular function and nonsustained VT have all been identified as independent risk factors for future arrhythmic death. Similarly, patients with a history of sustained VT or a history of sudden cardiac death are a high-risk group and should be aggressively evaluated and treated. The purpose of this article is to discuss risk stratification and primary prevention of sustained ventricular arrhythmias. We also review the recent secondary prevention trials and discuss the options available in the management of patients with sustained ventricular arrhythmias.

Amiodarone and "primary" prevention of sudden death: critical review of a decade of clinical trials

Several trials have evaluated the role of amiodarone in decreasing mortality in patients at high risk of developing sudden death. Current evidence does not support the prophylactic use of amiodarone in myocardial infarction (MI) survivors with a depressed left ventricular function and/or frequent or complex ventricular ectopy. Some postinfarction trials (e.g., the Spanish Study of Sudden Death [SSSD]) found mortality rates in controls much lower than the expected figures. Other postinfarction trials--the European Amiodarone Myocardial Infarction Arrhythmia Trial (EMIAT) and the Canadian Amiodarone Myocardial Infarction Arrhythmia Trial (CAMIAT)--despite observing a 2-year mortality rate of about 15% as expected, could not demonstrate a significant reduction in mortality. Amiodarone decreases the risk of sudden death in postinfarction patients by about 35%. In patients with a history of heart failure and left ventricular dysfunction, evidence is not sufficiently strong to use amiodarone for prevention of sudden death. The 2 major trials on such patients, Group for the Study of Survival in Heart Failure in Argentina (Grupo de Estudio de la Sobrevida en la Insuficiencia Cardiaca en Argentina or GESICA) and the Survival Trial of Antiarrhythmic Therapy in Congestive Heart Failure (STAT-CHF), arrived at conflicting results. Meta-analyses have been performed to overcome the small sample size of these trials, with the aim of assessing the benefit of amiodarone on total mortality. Differences among the recruited populations make it difficult to extract clinically applicable conclusions from these overviews. Even accepting that amiodarone might decrease total mortality by 10%, it is difficult to identify the patients for whom such a beneficial effect applies. A practical consequence of amiodarone trials is that this drug can be used rather safely in patients with left ventricular dysfunction of any etiology as, in contrast to some class I agents, it does not increase mortality. Therefore, amiodarone is the drug of choice when antiarrhythmic drug treatment is indicated in patients with left ventricular dysfunction.

Intravenous amiodarone for ventricular arrhythmias: overview and clinical use

Numerous pharmacological agents with varying cellular electrophysiological effects are available to treat cardiac arrhythmias. Amiodarone is predominantly a Vaughan Williams Class III agent, but also possesses electrophysiological characteristics of the other three Vaughan Williams classes (Class I and IV and minor Class II effects). Amiodarone's primary mechanism is to prolong the cardiac action potential and repolarization time leading to an increased refractory period and reduced membrane excitability. The efficacy and tolerability of intravenous (IV) amiodarone for acute treatment of recurrent and refractory ventricular tachycardia and ventricular fibrillation has been demonstrated in clinical trials. The ARREST trial, a randomized trial comparing IV amiodarone to placebo, found a significant improvement in the proportion of patients surviving to the emergency department following out-of-hospital cardiac arrest in amiodarone-treated patients. Intravenous amiodarone is an effective anti-arrhythmic agent for the acute treatment of life-threatening ventricular arrhythmias and represents an important treatment option for emergency anti-arrhythmic therapy for patients suffering from cardiac arrest.

Antiarrhythmic drugs and devices for the management of ventricular tachyarrhythmia in ischemic heart disease

Ischemic heart disease is the most frequent cardiac abnormality in patients with sustained or nonsustained ventricular tachyarrhythmias. The goals of therapy in such patients are to decrease the severity and incidence of symptoms and prolong life. In this article, we review the current views on antiarrhythmic drug therapy and an implantable cardioverter-defibrillator (ICD) in patients with ischemic heart disease. The importance of beta blockade as part of the therapy is emphasized. In addition, the superiority of sotalol and amiodarone over class I drugs, the benefits of combined treatment with amiodarone and a beta blocker, and the impact and limitations of current trials comparing the effectiveness of drug therapy with that of an ICD are all considered. Also discussed is the combined use of an antiarrhythmic drug and an ICD. In this approach sotalol is generally the agent of choice, with amiodarone the second choice.

Ventricular arrhythmias in the elderly

Sudden cardiac death (SCD) remains a significant medical problem in the United States. The incidence of SCD increases with advancing age because cardiovascular disease is more prevalent in the elderly. Management of ventricular arrhythmias in the elderly patient is especially challenging because of increased risk of interventional and pharmacologic therapies, altered pharmacokinetics of drugs, and sometimes unclear long-term benefits.

Is hospital admission for initiation of antiarrhythmic therapy with sotalol for atrial arrhythmias required? Yield of in-hospital monitoring and prediction of risk for significant arrhythmia complications

OBJECTIVES

We sought to determine the yield of in-hospital monitoring for detection of significant arrhythmia complications in patients starting sotalol therapy for atrial arrhythmias and to identify factors that might predict safe outpatient initiation.

BACKGROUND

The need for hospital admission during initiation of antiarrhythmic therapy has been questioned, particularly for sotalol, with which proarrhythmia may be dose related.

METHODS

The records of 120 patients admitted to the hospital for initiation of sotalol therapy were retrospectively reviewed to determine the incidence of significant arrhythmia complications, defined as new or increased ventricular arrhythmias, significant bradycardia or excessive corrected QT (QTc) interval prolongation.

RESULTS

Twenty-five patients (20.8%) experienced 35 complications, triggering therapy changes during the hospital period in 21 (17.5%). New or increased ventricular arrhythmias developed in 7 patients (5.8%) (torsade de pointes in 2), significant bradycardia in 20 (16.7%) (rate <40 beats/min in 13, pause >3.0 s in 4, third-degree atrioventricular block in 1, permanent pacemaker implantation in 3) and excessively prolonged QTc intervals in 8 (6.7%) (dosage reduced or discontinued in 6). Time to the earliest detection of complications was 2.1 +/- 2.5 (mean +/- SD) days after initiation of sotalol, with 22 of 25 patients meeting criteria for complications within 3 days of monitoring. Baseline electrocardiographic intervals or absence of heart disease failed to distinguish a low risk group. Multivariate analysis identified absence of a pacemaker as the only significant predictor of arrhythmia complications (p = 0.022).

CONCLUSIONS

Because clinically significant complications can be detected with in-hospital monitoring in one of five patients starting sotalol therapy, hospital admission is warranted for initiation of sotalol. Patients without pacemakers are at higher risk for these complications.

Effects of amiodarone and desethylamiodarone on the inward rectifying potassium current (IK1) in rabbit ventricular myocytes

We examined the effects of amiodarone (AMI) and desethylamiodarone (DAM) on whole-cell inward rectifying potassium current (IK1) in freshly isolated adult rabbit ventricular myocytes by using the whole-cell voltage-clamp technique, as an index of their effects on resting membrane resistance (Rm). Under control conditions, the current showed a strong inward rectification with a maximal inward current measured at -130 mV of -26.4 +/- 1.3 pA/pF and a maximal outward current measured at -50 mV of 3.5 +/- 0.3 pA/pF The current also exhibit a time-dependent activation, with a time constant of activation (tau(a)) that increased with depolarization. The maximal slope conductance normalized to cell capacitance was 0.509 +/- 0.019 nS/pE After exposure to both DAM (50 microM; n = 8) and AMI (50 microM; n = 7), rapid decrease in inward IK1 was observed. Block was restricted almost exclusively to the inward component. DAM caused a significant reduction of the maximal inward current (-20.0 +/- 2.0 pA/pF; p < 0.05), whereas AMI induced an even greater reduction of the same component (-14.1 +/- 1.2 pA/pF; p < 0.05 with respect to control and to DAM). The outward component of IK1 was not changed by either AMI or DAM (4.0 +/- 0.3 pA/pF and 3.4 +/- 0.4 pA/pF, respectively). AMI and DAM also decreased the maximal slope conductance significantly (0.297 +/- 0.019 nS/pF and 0.421 +/- 0.038 nS/pF, respectively). In addition, AMI but not DAM significantly increased the tau(a). However, the voltage dependence of the acceleration of tau(a) remained unchanged after both AMI and DAM exposure. These results allow us to conclude that AMI may induce a greater increase in the resting Rm than its main metabolite. This effect may counterbalance, at least in part, the conduction slowing due to its sodium channel-blocking properties.

Cost-effectiveness analysis of invasive and noninvasive tests in high risk patients treated with amiodarone after acute myocardial infarction

OBJECTIVES

We sought to evaluate 1) the cost-effectiveness of amiodarone therapy in postinfarction patients; and 2) the influence of alternative diagnostic strategies (noninvasive only vs. noninvasive and electrophysiologic testing) on survival benefit and cost-effectiveness ratio of amiodarone therapy.

BACKGROUND

The cost-effectiveness of amiodarone therapy in postinfarction patients is still unknown, and no study has determined which diagnostic strategy should be used to maximize amiodarone survival benefit while improving its cost-effectiveness ratio.

METHODS

We designed a postinfarction scenario wherein heart rate variability analysis on 24-h Holter monitoring was used as a screening test for 2-year amiodarone therapy in a cohort of survivors (mean age 57 years) of a recent myocardial infarction. Three different therapeutic strategies were compared: 1) no amiodarone; 2) amiodarone in patients with depressed heart rate variability; 3) amiodarone in patients with depressed heart rate variability and a positive programmed ventricular stimulation. Total variable costs and quality-adjusted life expectancy during a 20-year period were predicted with use of a Markov simulation model. Costs and charges were calculated with reference to an Italian and American hospital.

RESULTS

Amiodarone therapy in patients with depressed heart rate variability and a positive programmed ventricular stimulation was dominated by a blend of the two alternatives. Compared with the no-treatment strategy, the incremental cost-effectiveness ratio of amiodarone therapy in patients with depressed heart rate variability was $10,633 and $39,422 per gained quality-adjusted life-year using Italian costs and American charges, respectively.

CONCLUSIONS

Compared with a noninterventional option, amiodarone prescription in all patients with depressed heart rate variability seems to be a more appropriate approach than the alternative based on the combined use of heart rate variability and electrophysiologic study.

KCB-328: a novel class III antiarrhythmic agent with little reverse frequency dependence in isolated guinea pig myocardium

The effects of 1-(2-amino-4-methanesulfonamidophenoxy)-2-[N-(3,4-dimethoxypheneth yl)-N-methylamino] ethane hydrochloride (KCB-328), in comparison with those of dofetilide, were studied on the action potentials (APs) of isolated guinea pig papillary muscles. KCB-328 (0.003-3 microM) concentration-dependently prolonged the AP duration at 90% repolarization (APD90) at 1- and 3-Hz pacing, and the concentration-response relations at 1 and 3 Hz resemble each other. Dofetilide (0.001-1 microM) also produced the concentration-dependent prolongation of APD90 but more pronouncedly at 1 than at 3 Hz, demonstrating the reverse frequency-dependent effect. KCB-328 at 0.03, 0.1, 0.3, and 1 microM increased APD90 by 11 +/- 1, 19 +/- 1, 25 +/- 1, and 29 +/- 1% at 3 Hz and by 9 +/- 1, 19 +/- 2, 27 +/- 2, and 33 +/- 2% at 1 Hz, respectively. Prolongation of the effective refractory period (ERP) by each drug is parallel to those of APD90 at each pacing frequency. KCB-328 modified neither the maximal velocity of depolarization, amplitude of AP, and resting membrane potential in the fast APs, nor any parameters of the slow APs. In a separate experiment, the effects of KCB-328 on the ERP of contractile response (ERPc) of excised guinea-pig papillary muscles also were studied at 1 and 3 Hz. KCB-328 (0.01-10 microM) lengthened the ERPc in a concentration-dependent and frequency-independent manner as in the electrophysiologic results. This frequency-independent ERPc prolongation by KCB-328 was not influenced by increased extracellular K+ concentration from 4 to 10 mM. These results suggest that KCB-328 might be a selective class III agent with effects that are relatively frequency independent.

The top ten fallacies of nonsustained ventricular tachycardia

Nonsustained ventricular tachycardia (NSVT) continues to remain a subject of controversy. This is true despite a wealth of epidemiologic and basic/clinical laboratory findings that have accumulated during the past 2 decades. However, these data not only generate the impetus to conduct further research, but also provide compelling arguments against continued adherence to time honored precepts about NSVT that evolved since the inception of the "PVC Hypothesis," although never substantiated by rigorous scientific inquiry. This paper discusses the "top ten" fallacies of NSVT and details the data that support abandonment of them.

Proarrhythmia with class III antiarrhythmic drugs: types, risks, and management

The nature of the proarrhythmic reactions induced by antiarrhythmic drugs is linked to the electrophysiologic effects of these agents. Torsades de pointes is the classic form of proarrhythmia observed during therapy with any drug that prolongs repolarization, for example, the class III agents. Its precise electrophysiologic mechanism is not fully elucidated, although the arrhythmia is generally considered to be due either to early afterdepolarization in the context of prolonged cardiac repolarization or to an increase in spatial or temporal dispersion of repolarization. Among the class III drugs the proarrhythmic risk appears to be lowest for amiodarone, probably due to its complex electrophysiologic profile that may create significant myocardial electrical homogeneity. In the case of d,l-sotalol, the incidence of torsades de pointes increases with dose and the baseline values of the QT interval. Where d-sotalol and other pure class III agents might fall into the varying spectrum of proarrhythmic potential remains unclear. That d-sotalol has been found to increase mortality in postinfarction patients with ventricular dysfunction (the Survival With Oral d-Sotalol [SWORD] trial) is a matter of considerable concern. It raises the possibility that such a phenomenon may be a common property of most, if not all, pure class III compounds. Accordingly, care must be taken to minimize the likelihood of proarrhythmia; in particular, therapy with a class III agent should only be initiated in the presence of a defined indication established on the basis of clinical trials. When class III antiarrhythmic drug-induced proarrhythmia occurs, immediate cessation of therapy with the responsible agent and correction of predisposing factors, such as electrolyte disorders or bradycardia, is mandatory. Intravenous administration of high-dose magnesium sulfate has been demonstrated to be effective in terminating and preventing new episodes of torsades de pointes. Temporary pacing may be necessary.

What can we expect from prophylactic implantable defibrillators?

Death due to ventricular tachyarrhythmia (VT) remains an important public health problem; patients with prior myocardial infarction (MI) constitute the largest identifiable population for prophylactic interventions. Targeting of progressively higher-risk subgroups of post-MI survivors carries inevitable tradeoffs with respect to the global impact of interventions on overall mortality. Therapy with aspirin, beta blockers, and angiotensin-converting enzyme (ACE) inhibitors comprise the benchmark against which all additional interventions, including implantable defibrillators, must be measured. Initial enthusiasm for empiric amiodarone therapy has been tempered by the limited benefit demonstrated in recent randomized trials. Trials of other class III antiarrhythmic drugs, including both d,l-sotalol and d-sotalol, have also failed to demonstrate survival benefit. The Multicenter Automatic Defibrillator Implantation Trial (MADIT) demonstrated significantly improved survival associated with defibrillators in a small subgroup of post-MI survivors with a high short-term risk of death. The ultimate number and optimal criteria for selection of patients who may benefit from prophylactic defibrillator therapy after MI will undergo continued evolution as new data from current and ongoing trials become available.

Evaluation and treatment strategies in patients at high risk of sudden death post myocardial infarction

Over 50 percent of deaths in patients who survive an acute myocardial infarction are due to fatal ventricular tachyarrhythmias. Patients who survive an episode of sustained ventricular arrhythmia are at highest risk of recurrent cardiac arrest. Electrophysiologic studies have been found to be useful in guiding therapy and reducing mortality in these patients and in patients with syncope due to arrhythmic etiology. Evaluation and treatment of nonsustained ventricular tachycardia post infarction remains somewhat controversial. A recently published trial (MADIT), however, showed improved survival with an implanted defibrillator in patients with coronary disease and asymptomatic nonsustained ventricular tachycardia. Asymptomatic patients post infarction at high risk include those who have significant left ventricular dysfunction, late potentials, high-grade ventricular ectopy, and abnormal heart rate variability. These tests individually, however, have a low positive predictive accuracy. This, combined with the fact that antiarrhythmic drugs are frequently not effective and can be proarrhythmic, leaves the best treatment for these patients uncertain. It is known, however, that beta-adrenoreceptor blocking agents do reduce mortality after an acute myocardial infarction. Early studies have shown mixed results relating to sudden death and total mortality with amiodarone. To date, no other antiarrhythmic drug has shown benefit, while several have been shown to be harmful. Recent studies have also shown some beneficial effects of angiotensin-converting enzyme inhibitors, carvedilol, a third-generation beta-blocking agent with vasodilator properties, and the angiotensin II receptor antagonist losartan. However, their precise role in reducing sudden death needs to be defined further.

Adverse effects of low dose amiodarone: a meta-analysis

OBJECTIVES

We sought to assess the odds of experiencing adverse effects with low dose amiodarone therapy compared with placebo.

BACKGROUND

An estimate of the likelihood of experiencing amiodarone-related adverse effects with exposure to low daily doses of the drug is lacking in the published reports, and little information is available on adverse effect event rates in control groups not receiving the drug.

METHODS

Data from four published trials involving 1,465 patients were included in a meta-analysis design. The criteria for inclusion were 1) double-blind, placebo-controlled design; 2) absence of a crossover design between patient groups; 3) mean follow-up of at least 12 months; 4) maintenance amiodarone dose < or = 400 mg/day; and 5) presence of an explicit description of adverse effects. Data were pooled after testing for homogeneity of treatment effects across trials, and summary odds ratios were calculated by the Peto-modified Mantel-Haenszel method for each adverse effect.

RESULTS

The mean amiodarone dose per day ranged from 152 to 330 mg; 738 patients were randomized to receive amiodarone and 727 placebo. Exposure to amiodarone in this dose range, for a minimal duration of 12 months, resulted in odds similar to those of placebo for hepatic and gastrointestinal adverse effects, but in significantly higher odds than those of placebo (p < 0.05) for experiencing thyroid (odds ratio [OR] 4.2, 95% confidence interval [CI] 2.0 to 8.7), neurologic (OR 2.0, 95% CI 1.1 to 3.7), skin (OR 2.5, 95% CI 1.1 to 6.2), ocular (OR 3.4, 95% CI 1.2 to 9.6) and bradycardic (OR 2.2, 95% CI 1.1 to 4.3) adverse effects. A trend toward increased odds of pulmonary toxicity was noted (OR 2.0, 95% CI 0.9 to 5.3), but this did not reach statistical significance (p = 0.07). The unadjusted total incidence of drug discontinuation was 22.9% in the amiodarone group and 15.4% in the placebo group. The odds of discontinuing the drug in the amiodarone group was approximately 1.5 times that of the placebo group (OR 1.52, 95% CI 1.2 to 1.9) (p = 0.003).

CONCLUSIONS

Compared with placebo, there is a higher likelihood of experiencing several amiodarone-related adverse effects with exposure to low daily doses of the drug. Thus, although low dose amiodarone may be well tolerated, it is not free of adverse effects.

Amiodarone: the expanding antiarrhythmic role and how to follow a patient on chronic therapy

Amiodarone was introduced as an antiarrhythmic compound in the early 1970s and was approved in the U.S. for the treatment of refractory ventricular arrhythmias in late 1984. Since that time the drug has become the most widely studied antiarrhythmic compound with expanding potential indications, including maintaining stability of sinus rhythm, secondary prevention in the survivors of myocardial infarction, and prolongation of survival in certain subsets of patients with congestive heart failure. Intravenous amiodarone was introduced in the U.S. in 1995 for the control of recurrent destabilizing ventricular tachycardia or ventricular fibrillation resistant to conventional therapy. The level of comfort in its use has risen considerably in the recent past. This has stemmed from the reasonably decisive evidence that class I agents increase mortality in patients with structural heart disease. In contrast, amiodarone either reduces mortality or its effect is neutral; this is consistent with its low to negligible proarrhythmic actions. The drug does not aggravate heart failure and it may even increase left ventricular ejection fraction and improve exercise capacity. Above all, it is becoming increasingly evident from wider experience and from controlled clinical trials that the side-effect profile of the drug is not as compelling an issue as it appeared to be when first used in much higher doses. Therefore, the overall objective of amiodarone therapy is to use the lowest dose that produces a defined therapeutic end point without causing serious side effects. Careful clinical surveillance in conjunction with monitoring of certain laboratory parameters and indices of efficacy at regular intervals permits the drug to be used effectively in a large number of patients who fail to respond to, or are intolerant of other antiarrhythmic compounds. Many experienced clinicians have begun to consider the use of amiodarone as first-line therapy in certain disorders of rhythm, especially in patients with severely compromised ventricular function.

Amiodarone therapy in chronic heart failure and myocardial infarction: a review of the mortality trials with special attention to STAT-CHF and the GESICA trials. Grupo de Estudio de la Sobrevida en la Insuficiencia Cardiaca en Argentina

Amiodarone appears to reduce sudden death in patients with left ventricular dysfunction resulting from an acute MI or a primary dilated cardiomyopathy, particularly if complex ventricular arrhythmias are present. Amiodarone's beneficial effect on mortality in these patients could be unrelated to its antiarrhythmic effects. Multiple factors could account for the improvement in mortality such as the drug's antiischemic effects, neuromodulating effects, its effect on left ventricular function and on heart rate. Moreover, patients with LV dysfunction who have survived an episode of sudden death would potentially benefit from amiodarone therapy. Future trials are needed to determine the precise subsets(s) of patients who would benefit from the drug and the most efficacious dosing regimen for the drug. Based on available data, amiodarone is the only antiarrhythmic agent which has not been shown to increase mortality in patients with chronic heart failure.

Randomised trial of outcome after myocardial infarction in patients with frequent or repetitive ventricular premature depolarisations: CAMIAT. Canadian Amiodarone Myocardial Infarction Arrhythmia Trial Investigators

BACKGROUND

Survivors of acute myocardial infarction with frequent or repetitive ventricular premature depolarisations (VPDs) have higher mortality 1-2 years after the event than those without VPDs. Although there is no therapy of proven efficacy for such patients, previous studies of amiodarone have been encouraging. CAMIAT was a randomised double-blind placebo-controlled trial designed to assess the effect of amiodarone on the risk of resuscitated ventricular fibrillation or arrhythmic death among survivors of myocardial infarction with frequent or repetitive VPDs (> or = 10 VPDs per h or > or = 1 run of ventricular tachycardia).

METHODS

Patients from 36 Canadian hospitals were randomly assigned amiodarone or placebo; a loading dose of 10 mg/kg daily for 2 weeks, a maintenance dose of 300-400 mg daily for 3.5 months, 200-300 mg daily for 4 months, and 200 mg for 5-7 days per week for 16 months. Patients were followed up for 2 years. The primary outcome was the composite of resuscitated ventricular fibrillation or arrhythmic death.

FINDINGS

We recruited 1202 patients (606 in the amiodarone group and 596 in the placebo group). The mean follow-up was 1.79 years (SD 0.44). In the efficacy analysis, resuscitated ventricular fibrillation or arrhythmic death occurred in 39 (6.9%) [corrected] patients in the placebo group and in 25 (4.5%) [corrected] in the amiodarone group (relative-risk reduction 48.5% [95% CI 4.5 to 72.2], p = 0.016). In the intention-to-treat analysis, primary outcome events occurred in 24 (6.9%) patients in the placebo group and in 15 (4.5%) in the amiodarone group (38.2% [95% CI -2.1 to 62.6], p = 0.029). The absolute-risk reductions were greatest among patients with congestive heart failure or a history of myocardial infarction.

INTERPRETATION

Amiodarone reduces the incidence of ventricular fibrillation or arrhythmic death among survivors of acute myocardial infarction with frequent or repetitive VPDs. Treatment decisions for individual survivors should require an assessment of their baseline risk factors and judgments based on the synthesis of our findings with those of related trials.

Randomised trial of effect of amiodarone on mortality in patients with left-ventricular dysfunction after recent myocardial infarction: EMIAT. European Myocardial Infarct Amiodarone Trial Investigators

BACKGROUND

Ventricular arrhythmias are a major cause of death after myocardial infarction, especially in patients with poor left-ventricular function. Previous attempts to identify and suppress arrhythmias with various antiarrhythmic drugs failed to reduce or actually increase mortality. Amiodarone is a powerful antiarrhythmic drug with several potentially beneficial actions, and has shown benefit in several small-scale studies. We postulated that this drug might reduce mortality in patients at high risk of death after myocardial infarction because of impaired ventricular function, irrespective of whether they had ventricular arrhythmias.

METHODS

The European Myocardial Infarct Amiodarone Trial (EMIAT) was a randomised double-blind placebo-controlled trial to assess whether amiodarone reduced all-cause mortality (primary endpoint) and cardiac mortality and arrhythmic death (secondary endpoints) in survivors of myocardial infarction with a left-ventricular ejection fraction (LVEF) of 40% or less. Intention-to-treat and on-treatment analyses were done.

FINDINGS

EMIAT enrolled 1486 patients (743 in the amiodarone group, 743 in the placebo group). Median follow-up was 21 months. All-cause mortality (103 deaths in the amiodarone group, 102 in the placebo group) and cardiac mortality did not differ between the two groups. However, in the amiodarone group, there was a 35% risk reduction (95% CI 0-58, p = 0.05) in arrhythmic deaths.

INTERPRETATION

Our findings do not support the systematic prophylactic use of amiodarone in all patients with depressed left-ventricular function after myocardial infarction. However, the lack of proarrhythmia and the reduction in arrhythmic death support the use of amiodarone in patients for whom antiarrhythmic therapy is indicated.

The ESVEM trial: impact on treatment of ventricular tachyarrhythmias. Electrophysiologic Study Versus Electrocardiographic Monitoring

The ESVEM (Electrophysiologic Study Versus Electrocardiographic Monitoring) trial was a prospective, randomized study, initiated in 1983, to compare the outcome of patients in whom antiarrhythmic therapy was guided by serial electrophysiological study with the outcome of patients in whom therapy was guided by electrocardiographic monitoring. In a surprising finding, there was no difference in rates of arrhythmia recurrence or mortality between the two methods. Subsequent reanalyses using more stringent criteria for both methods or a combined assessment have not significantly improved the predictive accuracy of guided therapy. Because drug therapy in each limb was also randomized, a comparison of specific antiarrhythmic agents was also possible: sotalol therapy and the absence of previous antiarrhythmic drug therapy were associated with a reduction in arrhythmia recurrence. Survey data suggest that the results of this trial have influenced clinical practice.

Long-term cost-effectiveness of alternative management strategies for patients with life-threatening ventricular arrhythmias. Electrophysiologic Study versus Electrocardiographic Monitoring (ESVEM) Investigators

BACKGROUND

Serial antiarrhythmic drug testing guided by Holter monitoring and electrophysiologic study had similar clinical outcomes in the Electrophysiologic Study versus Electrocardiographic Monitoring (ESVEM) trial, while patients treated with sotalol had improved outcomes. The purpose of this study was to compare long-term cost-effectiveness of these management alternatives.

METHODS

Patients in the ESVEM trial were linked to computerized files of either the Health Care Finance Administration or the Department of Veterans Affairs. Total hospital costs and survival time over five year follow-up were measured using actuarial methods, and cost-effectiveness was calculated.

RESULTS

Patients randomized to therapy guided by electrophysiologic study had more hospital admissions, higher costs, and a cost-effectiveness ratio of $162,500 per life year added compared with therapy guided by Holter monitoring. Patients randomized to sotalol had fewer hospitalizations, lower costs, and better survival than patients randomized to other drugs, and sotalol was a dominant strategy in the cost-effectiveness analysis. Patients for whom an effective drug was found had fewer hospital admissions, lower costs, and longer survival. These findings were robust in sensitivity analyses and in bootstrap replications.

CONCLUSIONS

Serial drug testing guided by electrophysiologic study had an unfavorable cost-effectiveness ratio relative to Holter monitoring, while sotalol was cost-effective relative to other antiarrhythmic drugs.

Comparison of mortality from acute myocardial infarction between 1979 and 1992 in a geographically defined stable population

This study documents mortality from acute myocardial infarction (AMI), in hospital and at 1 year, for each of 3 selected 1-year periods in a stable community over a 13-year period beginning in 1979 and continuing into the thrombolytic era, to detect any changes occurring in conjunction with the introduction of new therapies. Every patient with AMI occurring in a geographically defined stable community (Hamilton, Ontario, Canada) in 3 1-year periods (1979 to 1980 [n = 816], 1986 to 1987 [n = 816], and 1991 to 1992 [n = 831]) was identified and clinically characterized by standardized criteria. Subsequent in-hospital and 1-year survival were ascertained prospectively. The 3 cohorts were similar in prognostic factors. Mean age was progressively greater over the study period from 63 years in 1979 to 1980, to 67 years in 1991 to 1992 (p = 0.02). There was no change in in-hospital mortality rates from 1979 to 1980 (17%) and 1986 to 1987 (16%). However, from 1986 to 1987 and 1991 to 1992, in-hospital mortality decreased from 16% to 9% (p < 0.001) and 1-year mortality decreased from 26% to 19% (p < 0.001). For patients who survived the hospital phase of AMI, 1-year mortality did not change and was between 11% and 12% in each of the 3 study periods. From 1986 to 1987 and 1991 to 1992, there was an increase in the use of thrombolytic therapy from 5% to 44% of patients. The acute use of aspirin increased from 30% to 88% and the acute use of beta blockers increased from 19% to 48% of patients. The observed increase in use of these agents could account for half of the actual mortality reduction observed. This prospective population-based survey demonstrates improved in-hospital survival after AMI associated with increased use of established effective therapies between 1987 and 1992. The 1-year mortality of hospital survivors of AMI was unchanged throughout the period of study, remaining at 11% to 12%.

Antiarrhythmic actions of amiodarone: a profile of a paradoxical agent

Amiodarone, a complex compound with variegated electropharmacologic and pharmacokinetic properties and an equally complex side-effect profile, continues to have a critical role in the control of ventricular and supraventricular tachyarrhythmias as the use of class I agents has declined. Such is also the case with sotalol. Unlike other so-called class III agents, amiodarone non-competitively blocks sympathetic stimulation, and its effects on repolarization are not associated with reverse use dependency. Rarely does it produce torsades de pointes despite its propensity to induce significant bradycardia and marked prolongation of the QT interval. During long-term therapy with the drug, there is no impairment of ventricular function; in fact, there are significant increases in the left ventricular ejection fraction during protracted amiodarone therapy in patients with heart failure. Long-term amiodarone administration consistently demonstrates marked efficacy in a wide spectrum of arrhythmias. The major limitation of amiodarone during long-term therapy is its unusual side-effect profile, although the increasing trend for low-dose drug therapy has demonstrated a major decline in the overall incidence of serious adverse reactions. Amiodarone is effective in controlling symptomatic ventricular tachycardia and fibrillation (VT/VF) in > 60-70% of patients when conventional agents (especially class I) are ineffective or not well tolerated. The efficacy of amiodarone compared with that of an implantable cardioverter-defibrillator in patients with VT/VF and in survivors of cardiac arrest remains uncertain when total mortality is used as the primary endpoint of comparison. Amiodarone suppresses ventricular ectopy and markedly suppresses nonsustained VT. It prevents inducible VT/VF in a small number of patients, but slows VT rate in a larger number. The role of the drug in prolonging survival in the postmyocardial infarction patient is unclear, although preliminary data from blinded studies suggest that the drug decreases arrhythmia-related mortality. Similarly, in heart failure, amiodarone has the potential to reduce total mortality but appears to be selectively effective in nonischemic rather than in ischemic cardiomyopathy. Intravenous amiodarone was recently introduced in the United States for the control of recurrent destabilizing VT or VF resistant to conventional therapy. There is also evolving data indicating that the drug might be the most potent agent in maintaining sinus rhythm in patients with atrial fibrillation or flutter converted chemically or electrically to sinus rhythm. However, blinded controlled comparative studies involving sotalol, quinidine, or pure class III drugs have not been carried out. The available data nevertheless suggest that, barring its side-effect profile, amiodarone is a desirable prototype of a broad-spectrum antifibrillatory and antiarrhythmic compound.

Effects of hypothyroidism on the vulnerability to ventricular fibrillation in dogs: a comparative study with amiodarone

It has been shown that thyroid hormone has a significant effect on the heart and that suppression of thyroid function may contribute to the antiarrhythmic effect of amiodarone. The study was aimed at investigating the effects of hypothyroidism, compared with those of amiodarone, on vulnerability to ventricular fibrillation in dogs. In this study, 25 adult dogs were randomly divided into three groups: a hypothyroid group following total thyroidectomy (n = 9), an amiodarone group (n = 8, 400 mg per day, 4 weeks), and a control group (n = 8). Both amiodarone and control groups were subjected to sham surgery. Five to 8 weeks after surgery, ventricular fibrillation threshold and other electrophysiological parameters were determined. Right ventricular effective refractory period, monophasic action potential duration, and ventricular fibrillation threshold were significantly increased in both the thyroidectomized and amiodarone-treated animals. There was no significant change in monophasic action potential duration dispersion. The incidence of ventricular fibrillation during ischemia and reperfusion was significantly reduced in both treated groups compared with the sham-operated euthyroid controls. These observations suggest that hypothyroidism has a significant antifibrillatory effect in dogs. Homogeneous prolongation of repolarization and refractoriness may contribute to the antifibrillatory action of hypothyroidism.