Beneficial effects of low dose amiodarone in patients with congestive cardiac failure: a placebo-controlled trial

Electro-metabolic coupling in multi-chambered vascularized human cardiac organoids

The study of cardiac physiology is hindered by physiological differences between humans and small-animal models. Here we report the generation of multi-chambered self-paced vascularized human cardiac organoids formed under anisotropic stress and their applicability to the study of cardiac arrhythmia. Sensors embedded in the cardiac organoids enabled the simultaneous measurement of oxygen uptake, extracellular field potentials and cardiac contraction at resolutions higher than 10 Hz. This microphysiological system revealed 1 Hz cardiac respiratory cycles that are coupled to the electrical rather than the mechanical activity of cardiomyocytes. This electro-mitochondrial coupling was driven by mitochondrial calcium oscillations driving respiration cycles. Pharmaceutical or genetic inhibition of this coupling results in arrhythmogenic behaviour. We show that the chemotherapeutic mitoxantrone induces arrhythmia through disruption of this pathway, a process that can be partially reversed by the co-administration of metformin. Our microphysiological cardiac systems may further facilitate the study of the mitochondrial dynamics of cardiac rhythms and advance our understanding of human cardiac physiology.

The Care of Patients With Atrial Fibrillation and Heart Failure

Atrial fibrillation (AF) and heart failure (HF) are the 2 emerging epidemics in global cardiovascular disease. AF remains the most common cardiac arrhythmia, affecting over 33 million adults worldwide, and continues to increase in prevalence as the populations of many nations age. The prevalence of HF also surges, now afflicting 37 million adults globally. Interestingly, these 2 disease processes share many of the same risk factors and stem from many of the same pathophysiologic derangements, with AF occurring in over half of all patients with HF and HF occurring in over one third of all patients with AF. Furthermore, exacerbation of one of these ailments often drives decompensation or compromises therapy of the other, and it has been widely reported that coexistence of AF in patients with HF portends a poorer prognosis. As a result, many clinicians now routinely face the problem of AF in the patient with HF. In this review, we highlight the fundamental pathologic forces embedded in the relationship between AF and HF and then proceed to a discussion on the management of these complex patients with a detailed exploration of the clinical data.

Chronic Amiodarone Use and the Risk of Cancer: A Systematic Review and Meta-analysis

Background

Observational studies have identified inconsistent associations between chronic use of amiodarone and cancer-related outcomes. We performed a systematic review and meta-analysis to evaluate cancer risk among patients receiving amiodarone.

Methods

We searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) to May 1, 2020. We included randomized controlled trials (RCTs) with follow-up ≥2 years that compared amiodarone (any dose) to any comparator (placebo, active pharmacologic or interventional comparator, or usual care), and reported ≥1 outcome of interest. We contacted authors of published chronic amiodarone trials for potentially unreported cancer outcomes. The primary outcome was cancer incidence. Secondary outcomes were cancer-related death and site-specific cancers. We determined risk ratios and 95% confidence intervals using a fixed-effect model, and statistical heterogeneity using I². We conducted prespecified subgroup and sensitivity analyses for amiodarone indication, amiodarone dose, duration of therapy, and trial-level risk of bias.

Results

From 1439 articles, we included 5 RCTs (n = 4357). Mean follow-up duration ranged from 21 to 37 months. We included previously unpublished cancer outcome data from 1 RCT. Our primary outcome was not reported in any RCT. There was no significant difference in cancer-related death between amiodarone (1.69%) and the comparator (1.75%) (risk ratio 0.96, 95% confidence interval 0.57-1.63; I² = 0%). There were no significant interactions from our subgroup or sensitivity analyses.

Conclusions

Chronic amiodarone use did not increase cancer-related deaths. Data from RCTs do not support an increased risk of cancer-related harms with amiodarone use, and these concerns should not deter use of amiodarone when indicated.

Evaluation of the effectiveness of infusion of bone marrow derived cell in patients with heart failure: A network meta-analysis of randomized clinical trials and cohort studies

Background: The aim of this study was to investigate the effectiveness of bone marrow-derived cells (BMC) technology in patients with heart failure and compare it with alternative therapies, including drug therapy, cardiac resynchronization therapy pacemaker (CRT-P), cardiac resynchronization therapy defibrillator (CRT-D).

Methods: A systematic review study was conducted to identify all clinical studies published by 2017. Using keywords such as "Heart Failure, BMC, Drug Therapy, CRT-D, CRT-P" and combinations of the mentioned words, we searched electronic databases, including Scopus, Cochrane Library, and PubMed. The quality of the selected studies was assessed using the Cochrane Collaboration's tool and the Newcastle-Ottawa. The primary and secondary end-points were left ventricular ejection fraction (LVEF) (%), failure cases (Number), left ventricular end-systolic volume (LVES) (ml), and left ventricular end-diastolic volume (LVED) (ml). Random-effects network meta-analyses were used to conduct a systematic comparison. Statistical analysis was done using STATA.

Results: This network meta-analysis covered a total of 57 final studies and 6694 patients. The Comparative effectiveness of BMC versus CRT-D, Drug, and CRT-P methods indicated the statistically significant superiority of BMC over CRT-P (6.607, 95% CI: 2.92, 10.29) in LVEF index and overall CRT-P (-13.946, 95% CI: -18.59, -9.29) and drug therapy (-4.176, 95% CI: -8.02, -.33) in LVES index. In addition, in terms of LVED index, the BMC had statistically significant differences with CRT-P (-10.187, 95% CI: -18.85, -1.52). BMC was also dominant to all methods in failure cases as a final outcome and the difference was statistically significant i.e. BMC vs CRT-D: 0.529 (0.45, 0.62) and BMC vs Drug: 0.516 (0.44, 0.60). In none of the outcomes, the other methods were statistically more efficacious than BMC. The BMC method was superior or similar to the other methods in all outcomes.

Conclusion: The results of this study showed that the BMC method, in general, and especially in terms of failure cases index, had a higher level of clinical effectiveness. However, due to the lack of data asymmetry, insufficient data and head-to-head studies, BMC in this meta-analysis might be considered as an alternative to existing treatments for heart failure.

Dataset for amiodarone adverse events compared to placebo using data from randomized controlled trials

The dataset presented here provides a detailed description of the adverse events of amiodarone versus placebo using data from 43 randomized controlled trials. Two authors (M.M., M.R.) independently extracted the data. The dataset also includes baseline patient characteristics, amiodarone loading and maintenance doses, as well as forest plots describing the relative risk (RR) of developing an adverse event related to the pulmonary, thyroid, hepatic, cardiac, skin, gastrointestinal, neurological, and ocular systems. The Mantel-Haenszel random effects model was used to determine the relative risk of adverse events of amiodarone compared to placebo. This dataset is complementary to our article “Meta-analysis Comparing the Relative Risk of Adverse Events for Amiodarone Versus Placebo”, which was published in the American Journal of Cardiology [1]. The data can be used to assess certain adverse events and their relation to amiodarone loading and/or maintenance dose.

Cardiac metabolism - A promising therapeutic target for heart failure

Both heart failure with reduced ejection fraction (HFrEF) and with preserved ejection fraction (HFpEF) are associated with high morbidity and mortality. Although many established pharmacological interventions exist for HFrEF, hospitalization and death rates remain high, and for those with HFpEF (approximately half of all heart failure patients), there are no effective therapies. Recently, the role of impaired cardiac energetic status in heart failure has gained increasing recognition with the identification of reduced capacity for both fatty acid and carbohydrate oxidation, impaired function of the electron transport chain, reduced capacity to transfer ATP to the cytosol, and inefficient utilization of the energy produced. These nodes in the genesis of cardiac energetic impairment provide potential therapeutic targets, and there is promising data from recent experimental and early-phase clinical studies evaluating modulators such as carnitine palmitoyltransferase 1 inhibitors, partial fatty acid oxidation inhibitors and mitochondrial-targeted antioxidants. Metabolic modulation may provide significant symptomatic and prognostic benefit for patients suffering from heart failure above and beyond guideline-directed therapy, but further clinical trials are needed.

Comparison of posttransplant outcomes in patients with no, acute, or chronic amiodarone use before heart transplantation

Background

Major concerns about the safety of pretransplant amiodarone use have been raised. As a result of its long half-life, the cardiac allograft is exposed to amiodarone posing potential risks such as bradycardia, requirement for pacemaker implantation, or increased mortality after heart transplantation (HTX).

Objective

The aim of this study is to investigate the posttransplant outcomes of patients with no, acute, or chronic amiodarone use before HTX.

Methods

This retrospective single-center study included 530 adult patients who received HTX between 06/1989 and 12/2012. Patients were stratified by their amiodarone therapy before HTX: no continuous amiodarone use (≤90 days before HTX), acute amiodarone use (≤90 days before HTX), and chronic amiodarone use (>90 days before HTX). Differences between the 3 groups in demographics, posttransplant medication, echocardiographic features, heart rates including occurrences of bradycardia, permanent pacemaker implantation, atrial fibrillation (AF), and survival were analyzed.

Results

A total of 412 patients (77.7%) were in the “no amiodarone” group, 23 patients (4.4%) in the “acute amiodarone” group, and 95 patients (17.9%) in the “chronic amiodarone” group. Left ventricular ejection fraction (P=0.5819), heart rates including occurrence of bradycardia during posttransplant week 1 (P=0.0979 and P=0.2695), week 2 (P=0.1214 and P=0.8644), week 3 (P=0.1033 and P=0.8894), and week 4 (P=0.2892 and P=0.8644), permanent pacemaker implantation within 30-day (P=0.8644), or overall follow-up after HTX (P=0.8664) were not significant between groups. Patients with chronic pretransplant amiodarone therapy had the lowest rate of early posttransplant AF (P=0.0065). There was no statistically significant difference between groups in 30-day (P=0.8656), 1-year (P=1.0000), 2-year (P=0.8763), 5-year (P=0.5174), or overall posttransplant follow-up mortality (P=0.1936).

Conclusion

Administration of acute or chronic pretransplant amiodarone was not related to an increased occurrence of bradycardia, requirement for permanent pacemaker implantation, or mortality after HTX. Importantly, chronic amiodarone use effectively reduced early AF after HTX, whereas acute amiodarone use showed no such effect.

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.

Anti-Arrhythmic Agents in the Treatment of Atrial Fibrillation

Although atrial fibrillation (AF) is the most common sustained arrhythmia seen during daily cardiovascular physician practice, its management remained a challenge for cardiology physician as there was no single anti-arrhythmic agents proved to be effective in converting atrial fibrillation and kept its effectiveness in maintaining sinus rhythm over long term. Moreover all the anti-arrhythmic agents that are used in treatment of AF were potentially pro-arrhythmic especially in patients with coronary artery disease and structurally abnormal heart. Some of these drugs also have serious non cardiac side effects that limit its long term use in the management of atrial fibrillation. Several new and investigational anti-arrhythmic agents are emerging but data supporting their effectiveness and safety are still limited. In this systematic review we examine the efficacy and safety of these medications supported by the major published randomized trials, meta-analyses and review articles and conclude with a summary of guidelines recommendations.

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.

Quantitative evaluation of drug or device effects on ventricular remodeling as predictors of therapeutic effects on mortality in patients with heart failure and reduced ejection fraction: a meta-analytic approach

OBJECTIVES

The purpose of this study was to quantitatively assess the relationship between therapy-induced changes in left ventricular (LV) remodeling and longer-term outcomes in patients with left ventricular dysfunction (LVD).

BACKGROUND

Whether therapy-induced changes in left ventricular ejection fraction (LVEF), end-diastolic volume (EDV), and end-systolic volume (ESV) are predictors of mortality in patients with LVD is not established.

METHODS

Searches for randomized controlled trials (RCTs) were conducted to identify drug or device therapies for which an effect on mortality in patients with LVD was studied in at least 1 RCT of > or = 500 patients (mortality trials). Then, all RCTs involving those therapies were identified in patients with LVD that described changes in LVEF and/or volumes over time (remodeling trials). We examined whether the magnitude of remodeling effects is associated with the odds ratios for death across all therapies or associated with whether the odds ratio for mortality was favorable, neutral, or adverse (i.e., statistically significantly decreased, nonsignificant, or statistically significantly increased odds for mortality, respectively).

RESULTS

Included were 30 mortality trials of 25 drug/device therapies (n = 69,766 patients; median follow-up 17 months) and 88 remodeling trials of the same therapies (n = 19,921 patients; median follow-up 6 months). The odds ratio for death in the mortality trials was correlated with drug/device effects on LVEF (r = -0.51, p < 0.001), EDV (r = 0.44, p = 0.002), and ESV (r = 0.48, p = 0.002). In (ordinal) logistic regressions, the odds for neutral or favorable effects in the mortality RCTs increased with mean increases in LVEF and with mean decreases in EDV and ESV in the remodeling trials.

CONCLUSIONS

In patients with LVD, short-term trial-level therapeutic effects of a drug or device on LV remodeling are associated with longer-term trial-level effects on mortality.

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.

Tolvaptan administration does not affect steady state amiodarone concentrations in patients with cardiac arrhythmias

BACKGROUND

Tolvaptan, a nonpeptide selective vasopressin receptor (V2) antagonist, is in development for the treatment of congestive heart failure and hyponatremia. Tolvaptan is primarily metabolized via CYP3A4. This study was conducted to determine the extent of the pharmacokinetic interaction between tolvaptan and steady state amiodarone, an antiarrhythmic drug commonly prescribed for patients with congestive heart failure and a known inhibitor of other drugs metabolized by CYP3A4.

METHODS

This was a multicenter, open-label, 1-arm, 3-period, sequential treatment study conducted in 11 men (10) and women aged 49 to 80 years. They were primarily Caucasian (20) subjects, with a history of cardiac arrhythmias who were otherwise healthy. Subjects were to have been on oral amiodarone maintenance therapy of 200 mg/day for at least 10 months. All subjects took 200 mg amiodarone once daily on each study day; on days 3 and 4, they were also coadministered 30 and 90 mg of tolvaptan, respectively. The plasma concentrations of amiodarone and its metabolite desethylamiodarone were determined for 24 hours postdose on days 2, 3, and 4, tolvaptan concentrations were determined for 24 hours postdose on days 3 and 4.

RESULTS

As determined by the ratio of the geometric means and 90% confidence intervals (0.5 to 2.0) for the maximal plasma concentration and the area under the curve during the dosing interval for both amiodarone and desethylamiodarone, tolvaptan coadministration had no effect on either amiodarone and desethylamiodarone disposition, as all the geometric mean ratios (amiodarone + tolvaptan [30 or 90 mg] vs amiodarone alone) were approximately 1.

CONCLUSION

Tolvaptan coadministration does not alter steady-state amiodarone or desethylamiodarone concentrations. Tolvaptan concentrations did not appear to be different from historical controls. The most frequently reported adverse event was polyuria (15 of 21 subjects for amiodarone + 30 mg tolvaptan); an expected outcome due to the known potent aquaretic action of tolvaptan. The combination of amiodarone and tolvaptan was well tolerated.

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.

Mechanisms of neurohormonal activation in chronic congestive heart failure: pathophysiology and therapeutic implications

Patients with chronic congestive heart failure have a sequential and incessant activation of those neurohormonal systems, which control body fluids, cardiac output and systemic blood pressure. Neurohormonal activation is initially selective and regional. Generalized activation is a late event in the natural history of congestive heart failure. Although the ultimate stimulus responsible for the activation of these neurohormonal systems is unknown, a decreased cardiac output and diminished effective blood volume have been proposed as the responsible mechanisms. However, extensive clinical and experimental research suggest that cardiac remodeling and loading of low-pressure cardiac receptors with sympathetic afferents could be the triggering events followed by unloading of high-pressure carotid receptors by decreased cardiac output and diminished effective blood volume.

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.

Significance and control of cardiac arrhythmias in patients with congestive cardiac failure

A wide spectrum of ventricular and supraventricular tachyarrhythmias occurs in the setting of congestive cardiac failure. However, the two most clinically significant are atrial fibrillation and ventricular tachycardia and fibrillation. In the past there has been much emphasis on premature ventricular contractions and more recently, on nonsustained ventricular tachycardia. For the most part, these arrhythmias are asymptomatic in heart failure. They are markers of sudden arrhythmic death but their suppression by antiarrhythmic drugs have not resulted in a reduction of total mortality. Two approaches have been used to this end. The first is the use of beta-adrenergic blocking drugs and antiarrhythmic agents such as amiodarone. Beta-blockers have been shown to significantly reduce sudden death as well as total mortality, while the effects of amiodarone have been less decisive. The prospective role of the implantable cardioverter defibrillator (ICD) is undergoing critical evaluation in patients with cardiac failure at high risk for sudden death. The elective role of the ICD is well established as first-line therapy in patients with heart failure resuscitated from sudden death and in those with sustained ventricular tachycardia in conjunction with conventional therapies for cardiac decompensation. The prevalence of atrial fibrillation rises as a function of severity of cardiac failure, but it is also in known that persistent atrial fibrillation with an uncontrolled ventricular response may induce heart failure. Controlled ventricular response may prevent congestive heart failure and improve left ventricular function. The two most common causes of atrial fibrillation in cardiac failure in Europe and America are ischemic heart disease and hypertension, while mitral valve disease remains the prevalent cause elsewhere. The choice of antiarrhythmic drugs for maintaining sinus rhythm is critical in the prevention of heart failure aggravation and proarrhythmic reactions of antiarrhythmic drugs. Amiodarone and dofetilide are most widely used in this context.

Low-dose amiodarone for patients with advanced heart failure who are intolerant of beta-blockers

The tolerability and effectiveness of amiodarone in patients with advanced heart failure (HF) who are intolerant of beta-blockers was investigated in 22 patients (13 with and 9 without 180+/-26 mg/day of amiodarone). Heart rate (HR), blood pressure (BP), left ventricular diastolic dimension and fractional shortening (FS) using echocardiography, plasma atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and norepinephrine concentrations were determined at baseline and after 1 and 3 months of therapy. Although 9 patients tolerated amiodarone without any signs of HF, it was exacerbated in 4 patients. In 10 patients taking amiodarone who could be followed medically for 3 months, HR decreased after 1 month and remained unchanged until after 3 months (81+/-12 vs 65+/-7 vs 65+/-7beats/min), accompanied by decreased concentration of BNP (688+/-485 vs 392+/-203 vs 261+/-192pg/ml). FS increased significantly only after 3 months (0.12+/-0.05 vs 0.14+/-0.05 vs 0.16+/-0.04). Amiodarone may be used in patients with advanced HF who are intolerant of beta-blockers.

Amiodarone inhibits interleukin 6 production and attenuates myocardial injury induced by viral myocarditis in mice

A recent study has shown that amiodarone inhibits the production of cytokines in vitro. This study was performed to examine the effects of amiodarone on survival, heart weight-to-body-weight ratio (HW/BW), myocardial lesions and cytokines production in a murine model of viral myocarditis induced by the encephalomyocarditis virus (EMCV). Four-week-old male DBA/2 mice were inoculated with the EMCV. To examine its effect on survival and HW/BW on day 14, mice were administered oral amiodarone (30 mg/kg) or the vehicle only once daily, starting 4 days before inoculation of the virus. The effects of amiodarone on histopathologic changes in myocardial lesions and myocardial cytokine production were studied in mice treated with amiodarone (10 mg/kg or 30 mg/kg) or vehicle, and killed day 7. The survival rate on day 14 was significantly higher in the amiodarone-treated mice than in the control mice. The HW/BW, histopathologic score of cellular infiltration and myocardial interleukin 6 concentration were significantly lower in the amiodarone-treated group than in the control group. Likewise, myocardial necrotic area was significantly smaller in the amiodarone group than in the control group. This study suggests that the beneficial effects of amiodarone in viral myocarditis may be mediated by decreasing interleukin 6 production in myocardial tissue.

[Evidence based medical treatment of heart failure]

INTRODUCTION AND OBJECTIVES

Recommendations for the treatment of heart failure were carried out by a systematic review of the available evidence of the different pharmacologic treatments.

MATERIAL AND METHODS

The review focused on the treatment of chronic and systolic heart failure. All the studies published in english about the pharmacologic treatment of heart failure where identified. The evidence of every pharmacologic treatment was classified according to: a) efficacy variables (reduction of mortality and hospitalizations, improvement of functional class, ejection fraction and exercise tolerance), and b) the level of quality of the evidence according to an evaluation scale. The evidence was also reviewed for the comparisons and the combinations of the pharmacologic treatments, as well as for the toxicity and costs of treatments.

RESULTS

The recommendations were defined according to the NYHA functional class and were classified in the A, B and C categories according to the level of quality of the available evidence. The evidence on mortality was considered the most important. First line drugs, the alternatives and other possible treatments were take into account.

CONCLUSIONS

There is enough evidence based on information about some variables such as reduction of mortality or hospitalizations to carry out treatment recommendations in all stages of heart failure. This point out the interest ant the priority of used them in the evaluation and improvement of the results of heart failure.

Single-day loading dose of oral amiodarone for the prevention of new-onset atrial fibrillation after coronary artery bypass surgery

BACKGROUND

Various regimens have been proposed for the prevention of postoperative atrial fibrillation, including the use of intravenous and oral amiodarone. The purpose of this study was to determine the effectiveness of a single-day loading dose of oral amiodarone in prophylaxis of atrial fibrillation during the 7 days after coronary artery bypass surgery.

METHODS

We conducted a double-blind, randomized, placebo-controlled study encompassing 315 consecutive patients who underwent coronary artery bypass surgery. They received either amiodarone (159 patients) or placebo (156 patients). Therapy consisted of a single oral loading dose of 1200 mg of amiodarone 1 day before surgery, followed by the maintenance dose of 200 mg daily during the next 7 days. Only episodes of atrial fibrillation lasting more than 1 hour or associated with hemodynamic compromise were taken into consideration.

RESULTS

Overall, the incidence of atrial fibrillation was similar in patients who received amiodarone (31/159, 19.5%) and placebo (33/156, 21.2%) (P = .78). However, amiodarone reduced the incidence of atrial fibrillation in elderly patients (age > or = 60 years): it occurred in 20 of 75 (26.7%) patients on amiodarone and in 28 of 65 (43.1%) patients in the placebo group (P = .05). There were no differences between the study groups regarding the postoperative intrahospital morbidity and mortality and the duration of hospital stay.

CONCLUSIONS

A single-day loading dose of oral amiodarone (1200 mg) does not prevent postoperative atrial fibrillation in a general population of patients undergoing coronary artery bypass surgery. However, it appears that this regimen reduces the occurrence of postoperative atrial fibrillation in elderly patients.

Early outcome of initiating amiodarone for atrial fibrillation in advanced heart failure

BACKGROUND

Little information exists about the early outcomes of initiating amiodarone for atrial fibrillation in patients with advanced heart failure. This study assessed the initial rate of success and complications of amiodarone therapy initiated for patients with atrial fibrillation during hospitalization for heart failure.

METHODS

We reviewed medical records for 37 consecutive patients with left ventricular ejection fractions </=40% who underwent initiation of amiodarone for atrial fibrillation during hospitalization on a heart failure service.

RESULTS

Atrial fibrillation was present in 35 (95%) and atrial flutter in 2 (5%), with mean duration of 30 months. New York Heart Association class was 3.1 (+/-1.1). Left ventricular ejection fraction was 24% +/- 7%. All patients had received oral amiodarone with an initial dose of 1.2 +/- 0.2 g/day. Bradyarrhythmia led to discontinuation of digoxin in 12 (32%) patients and to permanent pacemaker placement in 7 (19%) patients. Conversion to sinus rhythm occurred spontaneously in 2 patients and after electrical cardioversion in 26 patients, for an initial success of 76%. After a median follow-up of 9.5 months, 21 of 37 (57%) patients remained in sinus or atrial-paced rhythm. Amiodarone complications occurred after discharge in 5 (14%) patients, 4 with hypothyroidism.

CONCLUSIONS

Amiodarone with electrical cardioversion has a high initial success rate for treatment of atrial fibrillation in patients with heart failure with advanced systolic dysfunction. The major early side effect was bradyarrhythmia, frequently requiring discontinuation of digoxin or permanent pacemaker placement.

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.

Prevention of atrial fibrillation in the postoperative cardiac patient: significance of oral class III antiarrhythmic agents

Atrial fibrillation is a frequent complication of cardiac surgery and the most common reason for delay in discharge from the hospital after open-heart surgery. This review summarizes the results of studies that have examined the prophylactic value of orally administered sotalol and amiodarone in preventing atrial fibrillation after open-heart surgery. The reduction in the prevalence of postoperative atrial fibrillation is 50-90% for sotalol compared with 50-60% for amiodarone. Sotalol has a rapid onset of action, allowing it to be efficacious when used orally shortly after surgery. In contrast, amiodarone has a slow onset of action that necessitates either oral loading for several days before surgery or intravenous loading shortly before or after surgery. However, although patients who are poor candidates for beta blockade may not tolerate sotalol, amiodarone does not have this limitation. Although both sotalol and amiodarone have relative advantages and disadvantages, available data indicate that either agent can be used effectively in selected patients to reduce the risk of postoperative atrial fibrillation. Larger controlled comparative trials are needed to define the precise magnitude of benefit from these compounds relative to their side effect profiles.

Class III antiarrhythmic agents in cardiac failure: lessons from clinical trials with a focus on the Grupo de Estudio de la Sobrevida en la Insuficiencia Cardiaca en Argentina (GESICA)

The results of previous clinical trials, in a variety of clinical settings, showed that class I agents may consistently increase mortality in sharp contrast to the effects of beta blockers. Attention has therefore shifted to class III compounds for potential beneficial effects on long-term mortality among patients with underlying cardiac disease. Clinical trials with d-sotalol, the dextro isomer (devoid of beta blockade) of sotalol, showed increased mortality in patients with low ejection fraction after myocardial infarction and in those with heart failure; whereas in the case of dofetilide, the impact on mortality was neutral. Because of the complex effects of its actions as an alpha-adrenergic blocker and a class III agent, the impact on mortality of amiodarone in patients with heart failure is of particular interest. A meta-analysis of 13 clinical trials revealed significant reductions in all-cause and cardiac mortality among patients with heart failure or previous myocardial infarction. Among these were 5 controlled clinical trials that investigated the effects of amiodarone on mortality among patients with heart failure. None of these trials was large relative to the beta-blocker trials in the postinfarction patients. However, the larger 2 of the 5 amiodarone trials produced discordant effects on mortality, neutral in one and significantly positive in the other. Some of the differences may be accounted for by the differences in eligibility criteria and baseline characteristics. Future trials that may be undertaken to resolve the discrepancies may need to allow for the newer findings on the effects of concomitant beta blockers, implantable devices, and possibly, spironolactone. All these modalities of treatment have been shown in controlled clinical trials to augment survival in patients with impaired ventricular function or manifest heart failure. Additional trials, some of which are currently in progress, compare amiodarone with implantable devices and other therapeutic interventions, and should help to clarify the optimal management strategy for patients with underlying heart failure.

Antiarrhythmic agents for atrial fibrillation: focus on prolonging atrial repolarization

Atrial fibrillation (AF) has been the subject of considerable attention and intensive clinical research in recent years. Current opinion among physicians on the management of AF favors the restoration and maintenance of normal sinus rhythm. This has several potential benefits, including the alleviation of arrhythmia-associated symptoms, hemodynamic improvements, and possibly a reduced risk of thromboembolic events. After normal sinus rhythm has been restored, antiarrhythmic therapy is necessary to reduce the frequency of AF recurrence. In the selection of an antiarrhythmic agent, both efficacy and safety should be taken into consideration. Many antiarrhythmic agents have the capacity to provoke proarrhythmia, which may result in an increase in mortality. This is of particular concern with sodium-channel blockers in the context of patients with structural heart disease. Flecainide and propafenone are well tolerated and effective in maintaining sinus rhythm in patients without significant cardiac disease but with AF. Recent interest has focused on the use of class III antiarrhythmic agents, such as amiodarone, sotalol, dofetilide (recently approved), ibutilide (approved for chemical conversion of AF and atrial flutter), and azimilide (still to be approved) in patients with AF and structural heart disease. To date, amiodarone and sotalol still hold the greatest interest, and although controlled clinical trials with these agents have been few, a number are in progress and some have been recently completed. These agents are effective in maintaining normal sinus rhythm in patients with paroxysmal and persistent AF and are associated with a low incidence of proarrhythmia when used appropriately. Because of the relative paucity of placebo-controlled trials of antiarrhythmic agents in patients with AF, experience until recently has tended to dictate treatment decisions. Increasingly, selection of drug therapy is being based on a careful and individualized benefit-risk evaluation by means of controlled clinical trials, an approach that is likely to dominate the overall approach to the control of atrial fibrillation in the largest numbers of cases of the arrhythmia. Pharmacologic therapy is likely to be dominated by compounds that exert their predominant effect by prolonging atrial repolarization.

Impact of concurrent amiodarone treatment on the tolerability and efficacy of carvedilol in patients with chronic heart failure

OBJECTIVE

To assess the safety and efficacy of carvedilol when administered to heart failure patients already receiving amiodarone.

DESIGN

Retrospective analysis of the clinical outcome of 230 patients treated with carvedilol for chronic heart failure, stratified according to whether they were already receiving amiodarone (amiodarone group, 80 patients) or not (non-amiodarone group, 130 patients) at baseline.

SETTING

Heart failure clinic at a university affiliated public teaching hospital.

MAIN OUTCOME MEASURES

Incidence of adverse events; changes in functional status and echocardiographic dimensions at three months.

RESULTS

Adverse reactions to carvedilol occurred in 33 (41%) of the amiodarone group and 43 (29%) of the non-amiodarone group (p = 0.049). Carvedilol was discontinued in 21 (26%) of the amiodarone group and 37 (25%) of the non-amiodarone group (NS). The clinical outcome at three months did not differ significantly between the two groups; 31 (39%) of the amiodarone group improved their New York Heart Association status, 28 (35%) were unchanged, and 21 (26%) deteriorated compared with 67 (45%), 51 (34%), and 32 (21%), respectively, for the non-amiodarone group (NS). Both groups had highly significant decreases in heart rate and left ventricular end systolic dimension, and a significant increase in left ventricular ejection fraction after three months of carvedilol treatment, with no significant differences between the groups.

CONCLUSIONS

The beneficial effects of carvedilol on left ventricular remodelling, systolic function, and symptomatic status are not affected by concurrent treatment with amiodarone. Adverse reactions necessitating cessation of carvedilol are no more frequent in patients receiving amiodarone.

Oral amiodarone reduces incidence of postoperative atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is a common occurrence after heart operations that use cardiopulmonary bypass. It can cause life-threatening complications as well as delay discharge and increase hospitalization costs. The purpose of this study was to evaluate the effect of orally administered low-dose amiodarone on the incidence of new onset postoperative AF.

METHODS

In this prospective study, 226 consecutive adult patients (group A) who had various heart operations utilizing cardiopulmonary bypass between April and November of 1998 at the University of Miami/Jackson Memorial Hospital, were given oral amiodarone (200 mg three times a day), starting immediately after arrival in the intensive care unit until the day of hospital discharge. The incidence of new AF in this group of patients was assessed and compared with a historical group of 239 patients (group B) who had had cardiac operations with cardiopulmonary bypass in the preceding 9 months at the same institution.

RESULTS

Preoperative patient characteristics and procedure types were similar in the two groups. Among the 226 patients in group A, 13 (5.7%) had history of AF. Of the remaining 213 patients, new-onset AF occurred postoperatively in 10 (4.7%). Among the 239 patients in group B, 16 (6.7%) had history of AF. Of the remaining 223 patients, 44 (19.7%) developed new-onset AF (p < 0.001). Group A patients had a shorter length of hospital stay than those in group B (6.5 versus 7.8 days) but had a similar incidence of complications other than AF (23 of 226 patients in group A versus 24 of 239 in group B). The drug was well tolerated.

CONCLUSIONS

Postoperative low-dose amiodarone given orally to patients who had cardiopulmonary bypass was well tolerated and appeared to reduce the incidence of new-onset AF and decrease the length of hospital stay.

Duration of preoperative amiodarone treatment may be associated with postoperative hospital mortality in patients undergoing heart transplantation

OBJECTIVE

To assess the effect of preoperative amiodarone treatment on patient mortality after heart transplantation.

DESIGN

Retrospective study.

SETTING

Single-institution university hospital.

PARTICIPANTS

One hundred six consecutive patients with heart transplants.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were grouped according to duration of preoperative amiodarone treatment, and posttransplant mortality before hospital discharge was compared with patients not treated with amiodarone. The authors collected cardiovascular data in the preoperative and postoperative periods. There was a significant increase in posttransplant mortality before hospital discharge in patients treated with amiodarone for more than 4 weeks in the preoperative period (p < 0.05). Patients treated with amiodarone had significantly lower (p < 0.05) heart rates (mean heart rate, 103+/-19 beats/min) in the early postoperative period than patients not treated with amiodarone (mean heart rate, 111+/-15 beats/min), but there was no relationship with mortality (p = not significant). Patients who died had a significantly lower (p < 0.05) postoperative cardiac index (2.2+/-0.7 to 2.5+/-0.7) in the first 24 hours after cardiopulmonary bypass compared with patients who survived to hospital discharge (3.0+/-0.7 to 3.1+/-0.9), but there was no relationship to amiodarone treatment (p = not significant).

CONCLUSION

Preoperative amiodarone treatment for more than 4 weeks may be associated with a significant increase in postoperative mortality in patients undergoing heart transplantation. Therefore, the indications for amiodarone must be carefully considered and, if needed, the maintenance dose should be kept to a minimum.

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.

Effects of amiodarone on tumor necrosis factor-alpha levels in congestive heart failure secondary to ischemic or idiopathic dilated cardiomyopathy

Tumor necrosis factor-alpha (TNF-alpha) has been implicated in the pathogenesis of congestive heart failure and may be associated with an increase in mortality. A recent in vitro study showed that amiodarone decreases TNF-alpha production by human blood mononuclear cells in response to lipopolysaccharide. However, no previous clinical studies have determined the effect of chronic amiodarone therapy on TNF-alpha levels. Thus, the purpose of this study was to determine whether amiodarone affects TNF-alpha levels in patients with ischemic and nonischemic cardiomyopathy. TNF-alpha levels were analyzed by an enzyme-linked immunoassay using plasma samples at baseline, 1, and 2 years of follow-up in New York Heart Association class III patients (n = 40 in each of the placebo and amiodarone groups, mean ejection fraction 0.25+/-0.09) who were randomized in the Congestive Heart Failure-Survival Trial of Antiarrhythmic Therapy, a multicenter, double-blind, placebo-controlled study in which the effect of amiodarone on survival was investigated. TNF-alpha levels were elevated in both groups of patients at baseline, 6.6+/-3.1 and 7.7+/-5.3 pg/ml in the amiodarone and placebo groups, respectively (p = 0.3). There were no significant differences in demographic or clinical variables between the 2 groups. Amiodarone treatment was associated with a significant increase in TNF-alpha levels in patients with ischemic cardiomyopathy, 12.7+/-12.5 and 6.8+/-3.7 pg/ml in the amiodarone and placebo groups, respectively (p = 0.03) at 1 year. No change in TNF-alpha levels was observed in patients with nonischemic cardiomyopathy. In contrast to the in vitro data, amiodarone treatment is associated with an increase in TNF-alpha levels in patients with ischemic cardiomyopathy. This increase is not associated with an adverse effect on survival.

Spontaneous conversion and maintenance of sinus rhythm by amiodarone in patients with heart failure and atrial fibrillation: observations from the veterans affairs congestive heart failure survival trial of antiarrhythmic therapy (CHF-STAT). The Department of Veterans Affairs CHF-STAT Investigators

BACKGROUND

In a multicenter, double-blind, placebo-controlled study, the long-term effects of amiodarone on morbidity and mortality in patients with congestive heart failure (CHF) and atrial fibrillation (AF) were evaluated during a 4-year period.

METHODS AND RESULTS

Of 667 patients with CHF, 103 (15%) had AF at baseline. Of these, 51 were randomized to amiodarone and 52 to placebo. The group with sinus rhythm and the group in AF were comparable except for a higher proportion of AF in patients with nonischemic versus ischemic cardiomyopathy (41% versus 27%, P<0.005). The mean ventricular response (VR) during AF over 24 hours was reduced by amiodarone at 2 weeks (20%, P=0.001), at 6 months (18%, P=0.001), and at 12 months (16%, P=0.006). Maximal VR was reduced 22% (P=0.001) at 2 weeks, 19% (P=0.001) at 6 months, and 14% (P=0.001) at 12 months. Sixteen of 51 patients on amiodarone and 4 of 52 on placebo converted to sinus rhythm during the study (chi2=9.23, P=0.002). During follow-up, 11 of 268 patients in sinus rhythm on amiodarone at baseline and 22 of the 263 in sinus rhythm on placebo developed AF; the difference was significant (chi2=12.88, P=0.005). Analysis of total mortality during follow-up showed a significantly lower mortality rate (P=0. 04) in patients in AF at baseline who subsequently converted to sinus rhythm on amiodarone than in those who did not convert to sinus rhythm on the drug.

CONCLUSIONS

In patients with CHF, amiodarone has a significant potential to spontaneously convert patients in AF to sinus rhythm, with patients who convert having a lower mortality rate than those who do not. The drug prevented the development of new-onset AF and significantly reduced the VR in those with persistent AF.

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.

Predictors of outcome after radiofrequency catheter ablation of the atrioventricular node for atrial fibrillation and congestive heart failure

BACKGROUND

Although radiofrequency catheter ablation of the atrioventricular (AV) node is an established treatment for atrial fibrillation (AF) with uncontrolled ventricular response, factors that predict clinical outcome in patients with associated congestive heart failure (CHF) are unknown.

METHODS AND RESULTS

AV node ablation and permanent pacemaker implantation was performed in 44 consecutive patients (mean age 71+/-10 years) with CHF and AF associated with uncontrolled ventricular response. Immediately before ablation, mean left ventricular ejection fraction (EF) measured by 2-dimensional echocardiogram was 34.6%+/-9.8%, mean exercise tolerance time was 2.6+/-1.8 minutes, and mean quality of life score was 62.3+/-19.7. Complete AV block was achieved in all 44 patients but was complicated by death in 1 patient from cardiogenic shock soon after ablation. By 1 month after ablation, EF increased to 43.8%+/-13.7% (P < .01), exercise tolerance time was 4.0+/-2.5 minutes (P < .01), and mean quality of life score decreased to 35.6+/-18.1 (P < .01). Improved cardiac performance (increase in EF > or = 9% over baseline EF) was detected in 20 (45%) of the patients. During a mean follow-up of 17+/-9 months, 5 patients died suddenly of presumed ventricular tachyarrhythmia and 4 others died of progressive CHF. Multivariate Cox survival analysis identified baseline EF < or = 30%, presence of significant mitral regurgitation (>2+) before ablation, and failure to exhibit improved cardiac performance by 1 month after ablation as the only independent predictors of death.

CONCLUSIONS

Baseline variables and failure of EF to improve soon after AV node ablation identifies patients with CHF and AF who have a high mortality rate. Adjunctive therapy to reduce sudden death and progressive heart failure should be evaluated in this subgroup.

Overview and meta-analysis of randomised trials of amiodarone in chronic heart failure

Unlike other antiarrhythmic class I drugs, amiodarone showed in preliminary studies, benefits also in patients with left ventricular dysfunction. These positive results have induced the development of large randomised controlled studies: their results are reviewed and the controversial points are discussed. In a meta-analysis of randomised controlled trials the use of amiodarone in heart failure was associated with an approximate 20 to 25% reduction in deaths. However, amiodarone was also associated with a 120 to 124% increase in side effects.

A decade of clinical trial developments in postmyocardial infarction, congestive heart failure, and sustained ventricular tachyarrhythmia patients: from CAST to AVID and beyond. Cardiac Arrhythmic Suppression Trial. Antiarrhythmic Versus Implantable Defibrillators

Multiple trials using antiarrhythmic drugs, pharmacologic therapy, and implantable cardioverter defibrillators have been performed in an attempt to improve survival in patients: (1) postmyocardial infarction; (2) with congestive heart failure, with and without nonsustained ventricular tachycardia; and (3) with sustained ventricular tachycardia and those who have survived an out-of-hospital cardiac arrest. This article reviews some of the key findings and limitations of completed and ongoing trials. We also make recommendations for the current treatment of such patients based on the results of these trials.

Comparison of the effects of AV nodal ablation versus AV nodal modification in patients with congestive heart failure and uncontrolled atrial fibrillation

Radiofrequency (RF) catheter ablation of the atrioventricular node (AVN) and implantation of a ventricular pacemaker can improve cardiac performance in patients with congestive heart failure (CHF) and uncontrolled atrial fibrillation (AF). Alternatively, RF catheter modification of the AVN has been proposed to slow ventricular response during AF without requirement for permanent pacing. Among 44 consecutive patients (mean age 69.7 +/- 10.2 years) with drug resistant chronic AF, 22 (group I) had AVN ablation with permanent ventricular pacemaker implantation, while 22 patients had attempted AVN modification. Complete AV block was obtained in all group I patients while only seven (32%) AVN modification patients (group II) had permanent slowing of ventricular rate. Among patients in group I, mean left ventricular ejection fraction (EF) increased from 32.2% +/- 8.8% before ablation to 41.9% +/- 14.6% 4-weeks postablation (P < 0.01); exercise tolerance time (ETT) increased from 2.9 +/- 2.2 minutes to 4.5 +/- 2.9 minutes (P < 0.01); and quality-of-life score decreased from 66.1 +/- 22.6 to 36.9 +/- 17.1 (P < 0.01). By comparison, there was only a small increase in ETT in the seven successful group II patients (2.4 +/- 1.8 minutes to 3.0 +/- 1.9 minutes; P < 0.05) and there was no significant change in EF or quality-of-life. While AVN ablation can occasionally have transient adverse effects, it is more effective than AVN modification for improving cardiac performance in selected patients with CHF and AF.

Preoperative amiodarone as prophylaxis against atrial fibrillation after heart surgery

BACKGROUND

Atrial fibrillation occurs commonly after open-heart surgery and may delay hospital discharge. The purpose of this study was to assess the use of preoperative amiodarone as prophylaxis against atrial fibrillation after cardiac surgery.

METHODS

In this double-blind, randomized study, 124 patients were given either oral amiodarone (64 patients) or placebo (60 patients) for a minimum of seven days before elective cardiac surgery. Therapy consisted of 600 mg of amiodarone per day for seven days, then 200 mg per day until the day of discharge from the hospital. The mean (+/-SD) preoperative total dose of amiodarone was 4.8+/-0.96 g over a period of 13+/-7 days.

RESULTS

Postoperative atrial fibrillation occurred in 16 of the 64 patients in the amiodarone group (25 percent) and 32 of the 60 patients in the placebo group (53 percent) (P=0.003). Patients in the amiodarone group were hospitalized for significantly fewer days than were patients in the placebo group (6.5+/-2.6 vs. 7.9+/-4.3 days, P=0.04). Nonfatal postoperative complications occurred in eight amiodarone-treated patients (12 percent) and in six patients receiving placebo (10 percent, P=0.78). Fatal postoperative complications occurred in three patients who received amiodarone (5 percent) and in two who received placebo (3 percent, P= 1.00). Total hospitalization costs were significantly less for the amiodarone group than for the placebo group ($18,375+/-$13,863 vs. $26,491+/-$23,837, P=0.03).

CONCLUSIONS

Preoperative oral amiodarone in patients undergoing complex cardiac surgery is well tolerated and significantly reduces the incidence of postoperative atrial fibrillation and the duration and cost of hospitalization.

Quantitative overview of randomized trials of amiodarone to prevent sudden cardiac death

BACKGROUND

Some randomized clinical trials of amiodarone therapy to prevent sudden cardiac death have had positive results and others have had negative results, but all were relatively small. This meta-analysis aimed to pool all trials to assess the effect of amiodarone on mortality and the impact of differences in patient population and study design on trial outcomes.

METHODS AND RESULTS

Fifteen randomized trials were identified, and outcome measures were combined by use of a random effects model. The effect of patient population and study design on total mortality was assessed by use of a hierarchical Bayes model. Amiodarone reduced total mortality by 19% (confidence limits, 6% to 31%; P<.01), with somewhat greater reductions in cardiac mortality (23%, P<.001) and sudden death (30%, P<.001). Mortality reductions were similar in trials enrolling patients after myocardial infarction (21%), with left ventricular dysfunction (22%), and after cardiac arrest (25%). There was a trend toward greater risk reduction in trials requiring evidence of ventricular ectopy (25%) than in the remaining trials (10%). The trials using placebo controls had considerably less risk reduction (10%) than trials with active controls (27%) or usual care controls (42%, posterior odds <0.02).

CONCLUSIONS

Amiodarone reduced total mortality by 10% to 19% in patients at risk of sudden cardiac death. Amiodarone reduced risk similarly in patients after myocardial infarction, with heart failure, or with clinically evident arrhythmia. The apparent inconsistencies among results of randomized trials appear to be due to small sample sizes and the type of control group used, not the type of patient enrolled.

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.

Amiodarone inhibits production of tumor necrosis factor-alpha by human mononuclear cells: a possible mechanism for its effect in heart failure

BACKGROUND

Recent studies suggest that cytokines such as tumor necrosis factor (TNF)-alpha and interleukins (ILs) are capable of modulating cardiovascular function and that drugs used in the treatment of heart failure have various modulatory effects on the production of cytokines. This study was performed to examine the effects of amiodarone (a drug shown to be beneficial in some patients suffering from heart failure) versus other antiarrhythmic agents on the production of cytokines in vitro.

METHODS AND RESULTS

Human peripheral blood mononuclear cells (PBMC) were obtained from healthy volunteers. PBMC were cultured with 0.1, 1, and 10 micromol/L of amiodarone, quinidine, disopyramide, and lidocaine in the presence of lipopolysaccharide. After 24 hours' incubation, TNF-alpha, IL-1beta, and IL-6 were measured in the culture supernatants by an enzyme-linked immunosorbent assay. TNF-alpha production was inhibited by amiodarone but stimulated by quinidine in a concentration-dependent manner. Disopyramide and lidocaine tended to increase TNF-alpha production. IL-6 production was decreased by amiodarone in all concentrations but was increased significantly by disopyramide. Modulation of IL-1beta production by amiodarone was biphasic and significantly increased at a concentration of 10 micromol/L.

CONCLUSIONS

These previously unrecognized immunomodulatory effects of amiodarone may contribute to its beneficial effects in heart failure patients.