A trial of the beta-blocker bucindolol in patients with advanced chronic heart failure

Effect of nebivolol on left ventricular function in patients with chronic heart failure: a pilot study

BACKGROUND

Sympathetic activity is a significant predictor of a poor prognosis in heart failure. Beta-blockers have been shown to improve the prognosis of patients with heart failure.

AIM

This pilot study examined the tolerability and efficacy of the new beta-blocker nebivolol on left ventricular function in patients with chronic heart failure.

METHODS AND RESULTS

Twelve patients with an ejection fraction of 13-39% were included in this double blind, placebo-controlled randomized trial of nebivolol administered in addition to standard therapy. Exercise time, heart rate, left ventricular function and tolerability were examined at baseline and after 3 months of orally administered nebivolol (2.5 and 5 mg, n = 6) or placebo (n = 6). Nebivolol was well tolerated and the NYHA class improved in four patients. Heart rate decreased while the maximal exercise duration and performance remained stable. Left ventricular function increased (ejection fraction 31.5 +/- 10.11 to 42.0 +/- 10.99%, P < or = 0.01) after 12 weeks of nebivolol. The left ventricular end-systolic diameter decreased in the nebivolol-group from 56.5 +/- 9.40 to 50.2 +/- 9.43 mm (P < or = 0.02).

CONCLUSION

These data indicate that nebivolol might improve cardiac function in patients with reduced left ventricular function.

Optimising the use of beta-blockers in older patients with heart failure

Heart failure is predominantly a disease of the older person with half of all patients with the condition aged >75 years. Diuretics are the first-line symptomatic treatment for heart failure. beta-blockers should be initiated on an outpatient basis once the patient is stable, euvolaemic (by means of a diuretic) and established on an angiotensin converting enzyme (ACE) inhibitor. Large trials have demonstrated the beneficial effects of the beta-blockers carvedilol, metoprolol and bisoprolol in patients with heart failure, most of whom were also receiving ACE inhibitors. However, the mean age of patients in these trials was generally 60 to 65 years, with very few patients aged >75 years being recruited. It is, thus, not immediately clear how to apply these trial results to older patients with heart failure. Subgroup analyses from these large beta-blocker heart failure trials suggest that older patients gain similar benefit from beta-blocker treatment to younger patients. The trials, however, give no guidance as to whether older patients should receive the same target dosage or titration regimen as younger patients. It is suggested that a less aggressive titration regimen may be more appropriate for older patients while still attempting to achieve the trial target dosages. Titration can be safely achieved on an outpatient basis. In particular, a period of observation in the clinic after initiation of treatment does not appear to be necessary. The survival benefit resulting from the use of a beta-blocker in patients with heart failure is modest (months rather than years). It is, thus important not to neglect the effects of treatment on quality of life. A proportion of patients experience adverse effects with a beta-blocker. For such patients a balance needs to be made between the adverse effects on quality of life and the likely extension of life from the use of a beta-blocker. For patients who can tolerate a beta-blocker, the available evidence suggests that it can improve quality of life. The evidence currently available does not support the use of an angiotensin II receptor blocker (ARB) in addition to an ACE inhibitor and beta-blocker. For patients unable to tolerate an ACE inhibitor or beta-blocker, the use of an ARB may confer some advantage.

Effect of beta-blocking therapy on outcome in the Multicenter UnSustained Tachycardia Trial (MUSTT)

BACKGROUND

Beta-blockers are known to reduce total mortality and sudden death in survivors of recent myocardial infarction. The effects of these agents in patients at high risk for sudden death with remote infarction are not clear.

METHODS AND RESULTS

We analyzed the effect of beta-blockers on outcomes in 2096 patients with coronary artery disease, ejection fraction < or =40%, and spontaneous nonsustained ventricular tachycardia enrolled in the Multicenter UnSustained Tachycardia Trial (MUSTT). Forty-five percent of 702 patients with inducible sustained ventricular tachyarrhythmia and 35% of 1394 patients without inducible tachycardia were discharged from hospital receiving beta-blockers. Patients treated with beta-blockers were younger and had higher ejection fractions, higher rates of recent angina, and more recent infarction. beta-Blockers were associated with decreased total mortality for the entire study population (5-year mortality 50% with beta-blockers versus 66% without beta-blockers; adjusted P=0.0001). The mortality benefit associated with beta-blockers was present in patients with and without inducible tachycardia, except those treated with implantable defibrillators. There was no significant effect of beta-blocker therapy on the rate of arrhythmic death or cardiac arrest (adjusted P=0.2344).

CONCLUSIONS

beta-Blocking agents have beneficial effects on survival of patients having characteristics of those enrolled in the MUSTT trial. These effects do not appear to be due to a specific antiarrhythmic effect of beta-blockers. The beneficial effects of beta-blockers were demonstrable in all patients except those treated with implantable defibrillators.

Effects of valsartan on circulating brain natriuretic peptide and norepinephrine in symptomatic chronic heart failure: the Valsartan Heart Failure Trial (Val-HeFT)

BACKGROUND

Brain natriuretic peptide (BNP) and norepinephrine (NE) are strongly related to severity of and are independent predictors of outcome in heart failure. The long-term effects of angiotensin receptor blockers on BNP and NE in heart failure patients are not known.

METHODS AND RESULTS

Both BNP and NE were measured in 4284 patients randomized to valsartan or placebo in the Valsartan Heart Failure Trial (Val-HeFT) at baseline and 4, 12, and 24 months after randomization. The effects of valsartan were tested by ANCOVA, controlling for baseline values and concomitant ACE inhibitors and/or beta-blockers. BNP and NE concentrations were similar at baseline in the 2 groups and were decreased by valsartan starting at 4 months and up to 24 months. BNP increased over time in the placebo group. At the end point, least-squares mean (+/-SEM) BNP increased from baseline by 23+/-5 pg/mL in the placebo group (n=1979) but decreased by 21+/-5 pg/mL (n=1940) in the valsartan group (P<0.0001). NE increased by 41+/-6 pg/mL (n=1979) and 12+/-6 pg/mL (n=1941) for placebo and valsartan, respectively (P=0.0003). Concomitant therapy with both ACE inhibitors and beta-blockers significantly reduced the effect of valsartan on BNP but not on NE (P for interaction=0.0223 and 0.2289, respectively).

CONCLUSIONS

In Val-HeFT, the largest neurohormone study in patients with symptomatic chronic heart failure, BNP and NE rose over time in the placebo group. Valsartan caused sustained reduction in BNP and attenuated the increase in NE over the course of the study. These neurohormone effects of valsartan are consistent with the clinical benefits reported in Val-HeFT.

Renin angiotensin aldosterone and adrenergic modulation in chronic heart failure: contemporary concepts

Whereas the earlier conceptual targets of heart failure therapy, such as the cardio-renal and hemodynamic models, all fulfilled the basic needs of symptomatic relief and hemodynamic improvement, only the neurohormonal model has provided an effective target to address symptom relief in concert with survival benefits. Recent data allude to a disease-modifying effect of angiotensin-converting enzyme inhibitors (ACE-Is) in retarding the new development of heart failure in high-risk populations. Angiotensin receptor antagonists (ARBs) have not been demonstrated to be superior to ACE-Is and their value in achieving incremental benefits in addition to ACE-Is is limited to scenarios in which beta-adrenergic receptor blocker therapy is not applicable. Beta-adrenergic receptor blockade in addition to ACE inhibition offers incremental benefits that are achieved early and are beneficial in most stages of severity except in the presence of overt decompensation. Unlike ACE-Is, beta-adrenergic receptor blockers cannot be construed as a class but are heterogeneous in their therapeutic response.

Beta-blockers in chronic heart failure: considerations for selecting an agent

Patients with chronic heart failure have increased sympathetic nervous system activity that contributes to deterioration of cardiovascular function over time. Long-term beta-blocker therapy prevents such deterioration through inhibition of this neurohormonal pathway. The impressive survival data collected from several large studies have made beta-blockers a component of standard therapy for New York Heart Association class II to III heart failure. Although there are differences in the pharmacological properties of the beta-blockers shown to improve morbidity and mortality in heart failure, there is little evidence to suggest that such properties constitute any major advantages in clinical outcome. Carvedilol and extended-release metoprolol succinate are 2 beta-blockers currently approved in the United States for the treatment of patients with heart failure. Both agents have shown similar risk reductions in overall and cause-specific mortality; however, no outcome data from a comparative trial are available to support the use of one agent over the other. Regardless of the agent chosen, appropriate dosing and titration of beta-blockers are essential for successful therapy.

Systemic adverse effects of beta-adrenergic blockers: an evidence-based assessment

PURPOSE

To present an evidence-based review of the systemic adverse effects of beta-adrenergic blockers and recommend safety guidelines for use of ophthalmic beta-adrenergic blockers.

DESIGN

Literature review of published articles in peer-reviewed journals and medical texts.

METHODS

Pre-MEDLINE and MEDLINE search of relevant English language articles from 1966 to the present. Cardiovascular, pulmonary, endocrine/metabolic, central nervous system, sexual, exercise, and neuromuscular effects of systemic or ophthalmic beta-adrenergic blockers were reviewed.

RESULTS

Systemic beta-adrenergic antagonists unequivocally reduce mortality in patients with mild, moderate, and even severe congestive heart failure. Development of symptomatic bradycardia on systemic or ophthalmic beta-adrenergic blockers alone likely indicates underlying cardiac conduction disturbances. Beta 2-adrenergic blockade, regardless of route of administration, may exacerbate or trigger bronchospasm in patients with asthma or pulmonary disease associated with hyper-reactive airways. This review identifies no scientific studies supporting the development of worsening claudication, depression, hypoglycemic unawareness, or prolonged hypoglycemia in non-insulin-dependent diabetes, sexual dysfunction, or impaired neuromuscular transmission with systemic or ophthalmic beta-adrenergic blockers.

CONCLUSIONS

Many commonly presumed adverse beta-adrenergic blocker effects observed via systemic or ocular administration are not supported by published randomized clinical trials. Wide acceptance of such traditionally purported side effects has been largely due to propagation of isolated case reports and short series as well as personal communication felt to reflect expert opinion. Many more patients may be eligible to use these drugs. Obtaining a careful medical history and checking pulse rate and rhythm in the office should identify the vast majority of patients with potential cardiopulmonary contraindications.

Beta-adrenergic blocking drugs as antifibrillatory agents

Beta-Adrenergic blockade is associated with a significant reduction in mortality in most patients with structural heart disease. Clinical trial data involving patients after myocardial infarction or with congestive heart failure demonstrate that a reduction in sudden death accounts for much of the observed mortality reduction. Beta-adrenergic blockade inhibits the proarrhythmic effects of both neural and humoral sympathetic stimulation and inhibits the vagal withdrawal that accompanies ischemia. Although it does not have a dramatic effect on spontaneous ectopy or inducible monomorphic ventricular tachycardia, experimental and clinical data suggest that it inhibits the development of ventricular fibrillation by several mechanisms.

Beta-adrenergic blockade 2002: a pharmacologic odyssey in chronic heart failure

The treatment for heart failure has evolved considerably during the past two decades. Initially focused on hemodynamic derangement, diuretics and vasodilator agents were employed for symptomatic management. Beta blocking agents, with intrinsic negative inotropic activity, were considered specifically contraindicated. Neurohormonal activation subsequently became recognized and validated as a self-perpetuating influence on chronic heart failure and progressive adverse ventricular remodeling. Antagonism of the renin-angiotensin-aldosterone axis produced significant survival benefits in chronic heart failure populations. Concomitant intense sympathetic nervous system activation remained an additional therapeutic target. Pathophysiologic insights revealed a biologically plausible framework for the use of beta blocking agents in heart failure. This review summarizes the major clinical trials of beta blockers in heart failure populations with systolic left ventricular dysfunction. These trials support the integration of beta blockade as a critical component of standard therapy for chronic heart failure. Ongoing trials and unresolved issues are also discussed.

Beta-adrenergic blockers in systemic hypertension: pharmacokinetic considerations related to the current guidelines

Beta-adrenergic blockade has provided one of the major pharmacotherapeutic advances of the 20th century. Beta-blockers are first-line drugs for the management of systemic hypertension, used alone and in combination with other antihypertensive agents. Drugs in the beta-blocking class have the common property of blocking the binding of catecholamines to beta-adrenergic receptor sites; however, there are significant pharmacodynamic and pharmacokinetic differences between the individual agents that are of clinical importance. Among these differences are the completeness of gastrointestinal absorption, the degree of hepatic first-pass metabolism, lipid solubility, protein binding, brain penetration, concentration within the cardiac tissue, rate of hepatic biotransformation, and renal clearance of drug and/or metabolites. Long-acting formulations of existing beta-blockers are currently in use, and ultra-short-acting agents are also available. Age, race, cigarette smoking and concomitant drug therapy can also influence the pharmacokinetics of beta-blocking drugs. The wide interpatient variability in plasma drug concentrations observed with beta-blockers makes this parameter unreliable in routine patient management. Despite the pharmacokinetic differences among beta-blockers, these drugs should always be titrated to achieve the desired individual patient response.

Contemporary treatment of heart failure: is there adequate evidence to support a unique strategy for African-Americans? Pro position

Clinical trials provide average effects of interventions but are not powered to identify differences in subgroup responses. African-Americans have been under-represented in most previous trials in patients with heart failure. Furthermore, physiologic differences have been demonstrated between African-Americans and whites in the mechanisms and response to therapy in hypertension. Review of previous heart failure trials reveals that African-Americans exhibit less benefit than whites from ACE inhibitors, angiotensin receptor blockers, and at least one b-blocker. In contrast, black patients experienced a greater benefit than white patients from the combination of nitrate and hydralazine. These data emphasize the need for trials in black patients to identify effective therapy. The first such trial, African-American Heart Failure Trial, is currently underway.

Use of ejection fraction (or lack thereof), morbidity/mortality and heart failure drug trials: a review

Ejection fraction (EF) is an ejection phase parameter used to assess the performance of the heart in normal individuals and pathologic states such as myocardial infarction, dilated cardiomyopathy, and congestive heart failure (CHF). It can be measured by radionuclide ventriculography, angiocardiography, echocardiography and magnetic resonance imaging. EF is dependent on the loading conditions of the heart as well as contractility of the myocardium which makes it a less useful measure of cardiac performance. Nevertheless, it has been widely utilized and discussed for years. EF has been used as an entry criteria for many trials in CHF and has been used to characterize the hemodynamic effects of various classes of drugs which are used in treating CHF. How predictive an increase in EF on therapy is of morbidity and mortality is a matter of debate. This review outlines the utilization (or lack thereof), of EF in various CHF drug trials, its relationship to symptomatic improvement and morbidity/mortality.

Beta-blockers: new standard therapy for heart failure

Despite recent advances in the diagnosis and treatment of cardiovascular disease, the prevalence of heart failure, a highly morbid and lethal condition, is increasing. Because of recent advances in basic and clinical research, beta-blockade is now established as a highly effective therapy that reduces morbidity and mortality dramatically in patients with heart failure associated with reduced systolic function. The new guidelines from the American College of Cardiology-American Heart Association recommend use of beta-blockers in all patients with symptomatic left ventricular systolic dysfunction. Now clinicians need to incorporate use of beta-blockers into their standard approach to the treatment of heart failure. We briefly summarize the basic and clinical evidence establishing the benefit of beta-blockers for heart failure and provide practical information to assist clinicians in deciding when and how to use beta-blockers in patients with heart failure.

Contemporary treatment of heart failure: is there adequate evidence to support a unique strategy for African-Americans? Con position

Heart failure is a substantial cause of increased morbidity and mortality in the African-American population, with poorer prognosis versus white patients. Systolic heart failure is predominantly caused by poorly controlled hypertension in African-Americans. Overall, African-Americans remain underrepresented in morbidity and mortality heart failure trials, and further data are needed to confirm the potential benefit of present therapies and newer approaches to heart failure in African-Americans. Intensive blood pressure control and control of other risk factors, along with the appropriate application of evidence-based therapies including angiotensin converting enzyme (ACE) inhibitors and approved beta-blockers, are required to decrease racial disparities. Although some data suggest that contemporary treatment with ACE inhibitors and beta-blockers may be less effective in African-Americans in terms of reducing heart failure morbidity and mortality, there is not adequate evidence to support a unique strategy for this population. The use of evidence-based therapies should be equally applied to African-Americans as well as to other ethnic groups while awaiting further studies.

Suppressive effect of the Gly389 allele of the beta1-adrenergic receptor gene on the occurrence of ventricular tachycardia in dilated cardiomyopathy

Beta-1-adrenergic receptor (beta1-AR) blockers reduce both the incidence of sudden death and the ventricular volume in heart failure. In vitro, the Gly389 variant of beta1-AR mediates less adenylyl cyclase activities than the Arg389 variant, so Arg389Gly polymorphism was investigated with regard to the genesis, progression, or arrhythmogenesis of dilated cardiomyopathy (DCM). Allele and genotype frequencies of the Arg389Gly polymorphism were determined in 163 DCM patients and 157 age- and sex-matched controls. There were no differences in genotype and allele frequencies between patients and controls. Echocardiograms, left ventriculograms and 24h-Holter electrocardiograms were evaluated in the DCM patients and none of the clinical indices, other than ventricular tachycardia (VT), differed among the 3 genotypes. The Gly389 allele was more frequent in the VT(-) group than in the VT(+) group (0.46 vs 0.24, p=0.001). In univariate analysis, the odds ratio for VT in patients carrying 1 or 2 copies of the Gly389 allele was 0.29 ([95% confidence interval, 0.13-0.64], p=0.002), when compared with the Arg389 homozygotes. The Gly389 variant supressed the occurrence of VT in DCM, suggesting that this allele confers a decreased risk of sudden death.

The incomplete bucindolol evaluation in acute myocardial infarction Trial (BEAT)

The aim of this study was to evaluate the efficacy of adding the beta-blocker bucindolol to standard therapy shortly after a myocardial infarction in a high-risk population with reduced left ventricular function.

METHODS

The study was planned to include 2000 patients with an enzyme confirmed myocardial infarction and severely reduced left ventricular function determined by echocardiography (corresponding to ejection fraction < or =0.35). The primary endpoint was all cause mortality and the secondary endpoints were time to first event of death, progression of heart failure or reinfarction-and the components. The study was closed early due to discontinuation of development of bucindolol by the manufacturer. Therefore, 170 patients were randomised to receive bucindolol and 173 to receive placebo.

RESULTS

There were 27 deaths in the bucindolol group and 30 in the placebo group, hazard ratio of bucindolol 0.88 (95% confidence limits 0.5-1.5; P=0.6). There were 9/4 (bucindolol/placebo, P=0.16) heart failure events and 5/17 (P=0.01) reinfarctions in the bucindolol/placebo groups.

CONCLUSION

Due to early closure it is unknown whether bucindolol changes mortality in high-risk post myocardial infarct patients when added to best medical therapy. The frequency of reinfarction was significantly reduced.

Efficacy of angiotensin-converting enzyme inhibition in reducing progression from asymptomatic left ventricular dysfunction to symptomatic heart failure in black and white patients

OBJECTIVES

This study was undertaken to determine whether enalapril had comparable efficacy in black and white patients with asymptomatic left ventricular dysfunction (ALVD) in preventing the development of symptomatic heart failure (HF).

BACKGROUND

Recent studies have suggested that black patients with HF due to systolic dysfunction may derive less benefit than white patients with HF when treated with the same medication.

METHODS

This is a post hoc analysis of the 4,054 black and white participants of the Studies of Left Ventricular Dysfunction Prevention Trial.

RESULTS

Randomization to enalapril was associated with a comparable reduction in the relative risk of the development of symptomatic HF in black (relative risk [RR] 0.67, 95% confidence interval [CI] 0.49, 0.92, p = 0.01) and white patients (RR 0.61, 95% CI 0.53, 0.70, p < 0.001). Treatment with enalapril was also associated with a comparable reduction in the risk of the development of HF requiring medical therapy and the composite end point of death or development of HF in black and white patients. Black as compared with white patients with ALVD were at increased risk of the development of symptomatic HF (RR 1.81, 95% CI 1.51, 2.17, p < 0.001) despite adjustment for available measures of disease severity.

CONCLUSIONS

Despite the increased absolute risk in black patients compared with white patients for the progression of ALVD, enalapril was equally efficacious in reducing the risk of progression of ALVD in these two ethnic groups.

Physicians' interpretation of "class effects": a need for thoughtful re-evaluation

The concept of pharmacologic "class effects" exists across a broad range of medical products and is particularly pervasive with regard to cardiovascular agents. Evolution of the concept over the past two decades has shown the influence of physicians' practice patterns, pharmaceutical companies, health maintenance organizations and the Food and Drug Administration (FDA). Understanding the evolution of health care, social and economic policies, acknowledging the correction of medical misconceptions and inaccurate understanding and appreciating the emergence of new medical knowledge over the past decade should modify the clinician's viewpoint of "class effects." These revelations should signal caution in extrapolating the outcome efficacy or safety of one agent to another within a pharmacologic class. The authors urge clinicians, pharmaceutical companies, health maintenance organizations and the FDA to re-examine their concept of "class effects." An appeal is made for physicians to prescribe those pharmaceutical agents with definitive evidence of mortality and morbidity efficacy and safety established by appropriately scaled randomized clinical trials.

Prevalence and incidence of arrhythmias and sudden death in heart failure

Patients with heart failure are prone to a variety of arrhythmias, symptomatic and asymptomatic, that are prognostically significant and have an important bearing on the management of these patients. However there are some inherent problems in assessing the frequency of these arrhythmias within a large patient population, due to a lack of uniformity in defining heart failure and the transient nature of these rhythms. Patients with heart failure commonly die suddenly. The causes of these deaths are difficult to ascertain accurately and are often presumed arrhythmic. With the advent of effective interventions to prevent sudden death, accurately defining the causal relationship between the arrhythmias and sudden death has assumed great importance to appropriately target therapy. Several attempts have been made to predict such deaths on the basis of non-invasive and invasive diagnostic investigations with variable success. In this article we review the incidence and prevalence of atrial and ventricular arrhythmias and sudden deaths in epidemiological studies, surveys and randomised control trials of patients with heart failure. We discuss the prognostic significance of these arrhythmias, the inherent problems in their diagnosis and whether their presence predicts the risk of sudden deaths and the mode of such deaths in the heart failure population. The role of various investigations in risk stratification of sudden death has also been discussed.

Present and future pharmacotherapy for heart failure

The pharmacotherapy currently recommended by the American College of Cardiology and the American Heart Association for heart failure (HF) is a diuretic, an angiotensin-converting enzyme inhibitor (ACEI), a beta-adrenoceptor antagonist and (usually) digitalis. This current treatment of HF may be improved by optimising the dose of ACEI used, as increasing the dose of lisinopril increases its benefits in HF. Selective angiotensin receptor-1 (AT(1)) antagonists are effective alternatives for those who cannot tolerate ACEIs. AT(1) antagonists may also be used in combination with ACEIs, as some studies have shown cumulative benefits for the combination. In addition to being used in Stage IV HF patients, in whom it has a marked benefit, spironolactone should be studied in less severe HF and in the presence of beta-blockers. The use of carvedilol, extended-release metoprolol and bisoprolol should be extended to severe HF patients as these agents have been shown to decrease mortality in this group. The ancillary properties of carvedilol, particularly antagonism at prejunctional beta -adrenoceptors, may give it additional benefits to selective beta(1)-adrenoceptor antagonists. Celiprolol and bucindolol are not the beta-blockers of choice in HF, as they do not decrease mortality. Although digitalis does not reduce mortality, it remains the only option for a long-term positive inotropic effect, as the long-term use of the phosphodiesterase inhibitors is associated with increased mortality. The calcium sensitising drug levosimendan may be useful in the hospital treatment of decompensated HF to increase cardiac output and improve dyspnoea and fatigue. The antiarrhythmic drug amiodarone should probably be used in patients at high risk of arrhythmic or sudden death, although this treatment may soon be superseded by the more expensive implanted cardioverter defibrillators, which are probably more effective and have fewer side effects. The natriuretic peptide nesiritide has recently been introduced for the hospital treatment of decompensated HF. Novel drugs that may be beneficial in the treatment of HF include the vasopeptidase inhibitors and the selective endothelin-A receptor antagonists but these require much more investigation. However, disappointing results have been obtained in a large clinical trial of the tumour necrosis factor alpha antagonist etanercept, where no likelihood of a difference between placebo and etanercept was observed. Small clinical trials with recombinant growth hormone to thicken ventricles in dilated cardiomyopathy have given variable results.

Rationale and design of the carvedilol or metoprolol European trial in patients with chronic heart failure: COMET

In large clinical trials both carvedilol and metoprolol have been shown to reduce mortality and morbidity in patients with chronic heart failure. Carvedilol is an adrenoceptor antagonist, which inhibits beta(1)-, beta(2)-, and alpha(1)-adrenergic receptors. Carvedilol has additional metabolic and antioxidant properties. Metoprolol is a selective antagonist of beta(1)-adrenergic receptors. The carvedilol or metoprolol European trial (COMET) is the first study to investigate whether beta-blocking agents with differing pharmacological profiles exert different effects on morbidity and mortality in patients with chronic heart failure. 3029 patients from 15 different European countries were enrolled into COMET and will be followed until 1020 fatal events have been observed, unless the data and safety monitoring committee (DSMC) recommends early termination. The target dose for carvedilol is 25 mg bid and for metoprolol tartrate 50 mg bid. This manuscript outlines the rationale, design and possible outcomes of COMET.

African-American Heart Failure Trial (A-HeFT): rationale, design, and methodology

BACKGROUND

Hydralazine and isosorbide dinitrate combination (H+ISDN), angiotensin-converting enzyme inhibitors, and beta-blockers have improved outcomes in heart failure (HF). Analysis of previous trials has shown that H+ISDN appears especially beneficial in African American patients.

METHODS AND RESULTS

The African-American Heart Failure Trial (A-HeFT) is double-blind, placebo-controlled, and includes African American patients with stable New York Heart Association Class III-IV HF on standard therapy. Patients must have prior HF-related events and left ventricular ejection fraction (LVEF) < or = 35% or LVEF <45% with left ventricular internal diastolic dimension >2.9 cm/m(2). Randomization to addition of placebo or BiDil (Nitro Med, Inc., Bedford, MA), a fixed combination of H+ISDN, is stratified for beta-blocker usage. All patients are treated and followed until the last patient entered completes 6 months of follow-up. The primary efficacy endpoint is a composite score including quality of life, death, and hospitalization for HF. At least 600 patients will be randomized; the first was randomized in June 2001.

CONCLUSIONS

In addition to providing additional information on BiDil efficacy in HF, A-HeFT is the first HF trial aimed at a selected subgroup of patients and the first to use a new composite HF score as its primary efficacy endpoint.

Bucindolol displays intrinsic sympathomimetic activity in human myocardium

BACKGROUND

Most clinical studies have shown that beta-adrenergic receptor antagonists improve long-term survival in heart failure patients. Bucindolol, a nonselective beta-receptor blocker, however, failed to reduce heart failure mortality in a recent large clinical trial. The reasons for this failure are not known. Bucindolol has partial agonist properties in rat myocardium, but whether it has agonist activity in human heart is controversial. To address this, we measured the ability of bucindolol to increase cAMP accumulation in human myocardium.

METHODS AND RESULTS

Myocardial strips ( approximately 1 mm(3)) obtained from rat and nonfailing human hearts were confirmed to be viable for > or = 48 hours in normoxic tissue culture by MTT assay and histology. Freshly isolated strips were exposed to beta-adrenergic antagonists and agonists and assayed for cAMP. In both rat and human strips, the full beta-adrenergic agonist isoproterenol raised cAMP levels by >2.5-fold at 15 minutes. Carvedilol and propranolol had no effect on basal cAMP levels, whereas metoprolol reduced basal cAMP by approximately 25%. In contrast, bucindolol and xamoterol increased cAMP levels in a concentration-dependent manner in both rat and human myocardium (maximum 1.64+/-0.25-fold and 2.00+/-0.27-fold over control, respectively, P<0.01 for human tissue).

CONCLUSIONS

Bucindolol exhibits approximately 60% of the beta-adrenergic agonist activity of xamoterol in normal human myocardial tissue.

Statins and chronic heart failure: do we need a large-scale outcome trial?

Hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) are of proven clinical benefit in coronary heart disease, at least in those patients who do not have overt chronic heart failure (CHF). However, as there have been no prospective clinical trials of statins in CHF patients, the question arises as to whether the benefits observed in the absence of CHF can be necessarily inferred in those patients in whom CHF is established. In this review, the evidence base stating support of the use of statins in CHF is presented, as well as theoretical considerations as to why these agents may not necessarily be of benefit in this setting. The beneficial potential of statins clearly relates to their plaque stabilization properties and associated improvements in endothelial function, which together should reduce the risk of further infarction and, perhaps, the ischemic burden on the failing ventricle. Furthermore, these agents may have beneficial effects independent of lipid lowering. These include actions on neoangiogenesis, downregulation of AT(1) receptors, inhibition of proinflammatory cytokine activity and favorable modulation of the autonomic nervous system. The potential adverse effects of statins in CHF include reduction in levels of coenzyme Q10 (which may further exacerbate oxidative stress in CHF) and loss of the protection that lipoproteins may provide through binding and detoxifying endotoxins entering the circulation via the gut. In support of these possibilities are epidemiologic data linking a lower serum cholesterol with a poorer prognosis in CHF. These uncertainties indicate the need for a definitive outcome trial to assess the efficacy and safety of statins in CHF, despite their current widespread, non-evidence based use in this population.

The role of race in heart failure therapy

Heart failure in blacks is a unique malady characterized by a different natural history, more worrisome prognosis, and potential variances in the response to current medical therapy for heart failure. The overwhelming burden of hypertension as a putative cause of left ventricular dysfunction identifies this illness. Although differences in the response to medical therapy have been described, angiotensin-converting enzyme inhibitors and beta-blockers remain the most appropriate therapy. Certain genetic polymorphisms may exist that explain the observed differences.

Genes and their polymorphisms in mono- and multifactorial cardiomyopathies: towards pharmacogenomics in heart failure

Cardiomyopathies are diseases of the myocardium associated with cardiac dysfunction, and are classified as dilated cardiomyopathy (DCM), hypertropic cardiomyopathy (HCM) and restrictive cardiomyopathy. Heart failure and sudden death are the two major complications. Also, since DCM is the primary indication for heart transplantation and HCM the primary cause of sudden death in young athletes, the socioeconomic impact of these diseases is important. Recently, the role of the genetic background in both monogenic and multifactorial cardiomyopathies has been studied, which has led to a better understanding of the underlying mechanisms that promote the development and progression of these diseases. Preliminary data suggest interactions between pharmacological treatment and genetic polymorphisms, which appear to be the first steps towards the application of pharmacogenetics in heart failure.

Congestive heart failure due to systolic dysfunction: the Cinderella of cardiovascular management in dialysis patients

Cardiac disease is common in dialysis patients. Survival is poorest in the subgroup with systolic dysfunction (pump failure). Audits show that cardiovascular management of dialysis patients in general, and treatment of congestive heart failure (CHF) specifically, is generally not in agreement with recommendations based on evidence obtained from controlled trials, admittedly in nonrenal patients. The pathophysiology underlying CHF and the rationale underlying interventions are discussed in an effort to heighten awareness of this important clinical problem in the dialysis community.

A polymorphism in the beta1 adrenergic receptor is associated with resting heart rate

Resting heart rate is significantly associated with cardiovascular morbidity and mortality. However, the extent to which resting heart rate is genetically determined is poorly understood, and no genes have been found that contribute to variation in resting heart rate. Because signaling through the beta1 adrenergic receptor is a key determinant of cardiac function, we tested whether polymorphisms in this receptor are associated with resting heart rate. A cohort of >1,000 individuals of Chinese and Japanese descent, from nuclear families, was genotyped for two polymorphisms, resulting in a serine/glycine substitution at amino acid 49 (Ser49Gly) and an arginine/glycine substitution at residue 389 (Arg389Gly), in the beta1 adrenergic receptor. For comparison, polymorphisms in the beta2 and beta3 adrenergic receptors were also evaluated. The Ser49Gly polymorphism was significantly associated (P=.0004) with resting heart rate, independent of other variables, such as body-mass index, age, sex, ethnicity, exercise, smoking, alcohol intake, hypertension status, and treatment with beta blockers. The data support an additive model in which individuals heterozygous for the Ser49Gly polymorphism had mean heart rates intermediate to those of either type of homozygote, with Ser homozygotes having the highest mean heart rate and with Gly homozygotes having the lowest. Neither the Arg389Gly polymorphism in the beta1 adrenergic receptor nor polymorphisms in the beta2 and beta3 adrenergic receptors were associated with resting heart rate. The heritability of heart rate was 39.7% +/- 7.1% (P<10-7).

Bucindolol exerts agonistic activity on the propranolol-insensitive state of beta1-adrenoceptors in human myocardium

In congestive heart failure patients, treatment with beta-adrenoceptor antagonists improves symptoms and decreases mortality. However, intrinsic sympathomimetic activity of beta-adrenoceptor antagonists might be disadvantageous in chronic heart failure. The nonselective beta1- and beta2-adrenoceptor antagonist bucindolol has failed to decrease mortality in clinical trials. A putative beta4-adrenoceptor, which mediates positive inotropic effects by activation of the adenylate cyclase has been described. Recently, this putative beta4-adrenoceptor has been identified to be a propranolol-insensitive state of the beta1-adrenoceptor. The present study aimed to characterize whether bucindolol exhibits agonistic activity on this atypical beta1-adrenoceptor state as one possible reason for clinical inefficiency. For comparison (S)-4-(3'-t-butylamino-1'-hydroxypropoxy)-benzimidozole-2 (CGP 12177), metoprolol, and nebivolol were investigated. Bucindolol did not reveal intrinsic sympathomimetic activity in electrically driven (1 Hz, 37 degrees C), forskolin-stimulated, left ventricular papillary muscle strips (donor hearts, nonfailing; n = 5) and in right auricular trabeculae (bypass operation; n = 4). Functional studies on the propranolol-insensitive state of beta1-adrenoceptors were performed in isolated muscle preparations after beta1- and beta2-adrenoceptor antagonism (propranolol, 1 microM), inhibition of beta3-mediated inotropic effects (N-nitro-L-arginine, 100 microM) and forskolin treatment (0.3 microM). Positive inotropic response to stimulation of atypical state beta1-adrenoceptors could be demonstrated in right auricular as well as left ventricular human myocardium (CGP 12177 treatment, 10 microM). Under these conditions, also bucindolol, but not metoprolol and nebivolol, significantly increased contractility (all 10 microM). In conclusion, bucindolol but not metoprolol or nebivolol mediate positive inotropic effects in human myocardium due to activation of atypical state beta1-adrenoceptors. Thus, the agonistic activity of bucindolol may influence outcome in heart failure patients.

Role of race in the pharmacotherapy of heart failure

OBJECTIVE

To review the literature assessing the differences in response to angiotensin-converting enzyme (ACE) inhibitors and beta-blockers in black patients compared with the response in non-black patients in the management of systolic heart failure.

DATA SOURCES

A MEDLINE search (January 1966-May 2001) was performed using heart failure, blacks, Negroid race, adrenergic beta-antagonists, and angiotensin-converting enzyme inhibitors as key words. English-language articles were identified. Additional pertinent articles were identified from review of the references of these articles.

STUDY SELECTION AND DATA EXTRACTION

All identified references were reviewed. All articles deemed relevant to the subject of this article were included.

DATA SYNTHESIS

It has been suggested that the antihypertensive effect of ACE inhibitors and beta-blockers may be less in black patients than in other racial groups. Retrospective reanalyses of major heart failure trials have suggested that black patients may not realize a significant benefit in morbidity or mortality when heart failure is managed with ACE inhibitors or beta-blockers. It has also been suggested that black patients may respond more favorably than non-black patients to the combination of hydralazine and isosorbide dinitrate.

CONCLUSIONS

Published reanalyses of ACE inhibitor and beta-blocker trials in heart failure provide weak data to support a lack of benefit in black patients. The published literature on this topic is limited by its retrospective nature. Firm conclusions regarding the influence of race on effectiveness of ACE inhibitors and beta-blockers cannot be made until prospective trials, with planned analysis of the effect of race, have been performed.

Beta adrenergic blockers in chronic congestive cardiac failure: a call for action

Antagonism of adverse neuro-endocrine responses is the current paradigm by which chronic congestive cardiac failure is treated. Several recent large-scale randomized, controlled trials have confirmed the benefits of beta-adrenergic blocking agents in this regard. In light of the present heart failure 'epidemic', appropriate organization of services is mandatory to ensure that as many patients as possible can benefit from this life-saving therapy.

Efficacy of Beta Blockers in Severe Heart Failure

This continuing feature will update readers on recent developments in cardiovascular pharmacotherapy. Cardiovascular disease remains the number one killer in the US, and more clinical outcome trials have been conducted in cardiology than in any other field of medicine. Given this rapidly expanding knowledge base, pharmacists can have a significant impact on the prevention and treatment of cardiovascular disease—if they keep current with developments in drug therapy.

Contemporary use of beta receptor antagonists in chronic heart failure

beta-adrenergic receptor antagonists slow disease progression, improve symptoms, and increase survival. They should be considered standard of care for patients with stable heart failure and understanding which drugs provide benefit and how to initiate therapy is crucial to improving prognosis.

Genetic influences on rheumatoid arthritis in African Americans

Rheumatoid arthritis is a common autoimmune disease characterized by inflammation of the synovial membrane of diarthrodial joints, which often leads to joint damage and disability. There are known associations between major histocompatibility complex class II alleles and susceptibility to rheumatoid arthritis and its severity in Caucasians. African Americans, an admixed population in the United States, has been underrepresented in genetic studies of the susceptibility and severity of rheumatoid arthritis. With the advent of biologic agents, which target specific molecules of the immune system (e.g., tumor necrosis factor, interleukin-1), biologic markers of treatment response in Caucasians and in African Americans would be clinically useful.