Oral beta-adrenergic blockade with metoprolol in chronic severe dilated cardiomyopathy

β-blockers in stage B: a precursor of heart failure

β-blockers are an important treatment of heart failure (HF) and are useful in reducing the progression of the syndrome. They should be considered for patients with asymptomatic left ventricular (LV) dysfunction. Evidence-based β-blocker therapy (bisoprolol, carvedilol, or metoprolol succinate) in combination with standard therapy is a mainstay of treatment of all symptomatic patients with LV systolic dysfunction. Patients in stage B also benefit from the early introduction of β-blockers, but there are no large randomized clinical trials to support this strategy. Whether there is a role for ivabradine in the treatment of HF is not clear.

Safety and tolerability of once-daily controlled-release carvedilol 10-80 mg in Japanese patients with chronic heart failure

BACKGROUND

The aim of the present study was to assess the safety and tolerability of the controlled-release (CR) formulation of the β-blocker carvedilol in Japanese patients with chronic heart failure (HF).

METHODS AND RESULTS

In this multicenter, randomized, open-label, phase I/II dose-escalation study, 41 patients receiving standard therapy for chronic HF were randomized in a ratio of 1:1 to carvedilol CR or immediate-release (IR) carvedilol. The primary objective was to evaluate the tolerability and safety of escalating doses of carvedilol CR (10-40 mg/day), with a reference arm of 5-20 mg/day of carvedilol IR. In addition, the tolerability and safety of titration to a carvedilol CR dose up to 80 mg/day were examined, as were plasma concentrations of carvedilol and changes in vital signs. The proportions of patients who completed 40-mg/day carvedilol CR and 20-mg/day carvedilol IR were 42% (8/19) and 50% (11/22), respectively. In the CR group, 7/19 (37%) attained a dose of 80 mg. During the primary evaluation period, 7/19 (37%) and 4/22 (18%) patients experienced drug-related adverse events in the CR and IR groups, respectively, the characteristics of which were similar between groups.

CONCLUSIONS

No new safety issues emerged in Japanese chronic HF patients treated with carvedilol CR in contrast to those known in carvedilol IR.

Beta-adrenergic blockers for chronic heart failure

Systolic dysfunction and heart failure are major public health problems associated with a significant risk of morbidity and mortality. During the past 2 decades, considerable progress has been made in defining the underlying pathophysiology and the appropriate therapies in heart failure. In patients with chronic heart failure (CHF), sustained sympathetic overactivation leads to down-regulation of beta receptors and uncoupling of the receptors from adenylate cyclase. The clear understanding of the pivotal role of sympathetic overactivation in CHF has led to the evaluation of beta- blocker therapy in CHF. A number of large randomized clinical trials have been conducted with a variety of beta-blockers, and although most of them have shown benefit, there have been differing findings with different molecules. beta-blockers are now considered part of the standard therapy for all patients with symptomatic CHF. Despite the strong evidence supporting their use, beta-blockers continue to be underutilized in CHF.

The control of adrenergic function in heart failure: therapeutic intervention

Chronic heart failure is characterised by excess adrenergic activity that augurs a poor prognosis. The reasons for increased adrenergic activity are complex and incompletely understood. The circumstantial evidence relating increased activity to adverse outcome is powerful, but not yet conclusive. In normal subjects, autonomic control of the circulation is predominantly under the control of sympatho-inhibitory inputs from the arterial and cardiopulmonary baroreceptors, with a small input from the excitatory ergo- and chemo-receptors. In heart failure, the situation is reversed, with loss of the restraining input from the baroreceptors and an increase in the excitatory inputs, resulting in excessive adrenergic activity. The circumstantial evidence linking neuroendocrine activation with poor outcome coupled with the clinical success of inhibition of the renin-angiotensin-aldosterone system has long suggested that inhibition of adrenergic activity might be beneficial in heart failure. There is a number of potential ways of achieving this. Improved treatment of heart failure itself may reduce sympathetic drive. There is an interplay between angiotensin II, aldosterone and the sympathetic nervous system, and thus RAAS antagonists, such as angiotensin converting enzyme inhibitors and spironolactone could directly reduce sympathetic activation. Exercise rehabilitation may similarly reduce sympathetic activity.Recently, beta-adrenergic receptor antagonists have been conclusively shown to improve symptoms, reduce hospitalisations and increase survival. However, the demonstration that central reduction of sympathetic activity with agents such as moxonidine increases morbidity and mortality suggests that we do not properly understand the role of sympathetic activation in the pathophysiology of heart failure.

Beta-blockade in the management of systolic dysfunction

The concept that heart failure is simply the consequence of impaired pump function is now outmoded. Congestive heart failure is a neuroendocrine syndrome in with activation of the adrenergic nervous system and specific endocrine pathways is integral to its pathogenesis. It is now clear that chronic increases in adrenergic drive associated with heart failure have detrimental effects on myocardial function. The use of BAAs is now standard therapy for people who develop heart failure caused by systolic dysfunction. Beta-blockade may have a role in the management of dogs with heart failure.

Comprehensive adrenergic receptor blockade with carvedilol is superior to beta-1-selective blockade with metoprolol in patients with heart failure: COMET

The Carvedilol or Metoprolol European Trial (COMET) compared the effects of a comprehensive adrenergic antagonist, carvedilol (target dosage 25 mg twice daily), with a beta-1-selective agent, metoprolol tartrate (target dosage 50 mg twice daily), in 3029 patients with chronic heart failure caused by left ventricular systolic dysfunction. The study showed that, compared with metoprolol, long-term treatment with carvedilol exerted a substantially greater reduction in mortality and led to improvement in well-being in these patients. The superiority of carvedilol over metoprolol is readily explained by differences in their pharmacologic profiles. There is no evidence, within the trial or from other sources, that the relative dose of each agent or their formulation explained the observed difference. The result of COMET is entirely consistent with the results of previous placebo-controlled trials of beta-1-selective blockers and carvedilol.

Do β-blockers prolong survival in heart failure only by inhibiting the β1-receptor? A perspective on the results of the COMET trial

Experimental and clinical studies indicate that carvedilol exerts multiple antiadrenergic effects in addition to beta(1)-receptor blockade, but the prognostic importance of these actions has long been debated. This controversy has now been substantially advanced by the results of the recently completed Carvedilol Or Metoprolol European Trial (COMET), which showed that carvedilol (25 mg twice daily) reduced mortality by 17% when compared with metoprolol (50 mg twice daily), P=.0017--a result that was consistent with the differences seen across earlier controlled trials with beta-blockers in survivors of an acute myocardial infarction and in patients with chronic heart failure. Questions have been raised about the interpretation of these findings in view of the fact that the trial did not use the dose or formulation of metoprolol that was shown to prolong life in a placebo-controlled trial (ie, Metoprolol CR/XL [Controlled Release] Randomized Intervention Trial in Heart Failure). Pharmacokinetic and pharmacodynamic analyses, however, indicate that the dosing regimen of metoprolol selected for use in the COMET trial produces a magnitude and time course of beta(1)-blockade during a 24-hour period that is similar to the dose of carvedilol targeted for use in the trial. These analyses suggest that the observed difference in the mortality effects of metoprolol and carvedilol is not related to a difference in the magnitude or time course of their beta(1)-blocking effects but instead reflect antiadrenergic effects of carvedilol in addition to beta(1)-blockade.

Beta-blockers for chronic heart failure: surviving longer but feeling better?

Beta-blockers, as determined by four landmark placebo-controlled studies, impart a significant survival advantage to the chronic heart failure population. What ancillary benefits might be expected from beta-blockade, in terms of symptom relief and improvement in exercise capacity, is less clear. This situation in part reflects the heterogeneity of tools used to quantify quality of life and exercise performance as well as factors concerning the statistical handling of symptom and exercise data. In this review we explore the methodology and results of over 20 trials of carvedilol, metoprolol and bisoprolol where quality of life and measures of exercise capacity were end-points. A consistent message relating to a benefit from beta-blockade on these outcomes was elusive but the finding that patients on beta-blockers did at least as well as patients prescribed placebo was a unanimous verdict. There remains a dearth of data to help identify those patients that are at high risk of adverse events from beta-blocker therapy.

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.

Neurohormonal activation in heart failure after acute myocardial infarction treated with beta-receptor antagonists

BACKGROUND

Few studies have described how neurohormonal activation is influenced by treatment with beta-receptor antagonists in patients with heart failure after acute myocardial infarction. The aims were to describe neurohormonal activity in relation to other variables and to investigate treatment effects of a beta(1) receptor-antagonist compared to a partial beta(1) receptor-agonist.

METHODS

Double-blind, randomized comparison of metoprolol 50-100 mg b.i.d. (n=74), and xamoterol 100-200 mg b.i.d (n=67). Catecholamines, neuropeptide Y-like immunoreactivity (NPY-LI), renin activity, and N-terminal pro-atrial natriuretic factor (N-ANF) were measured in venous plasma before discharge and after 3 months. Clinical and echocardiographic variables were assessed.

RESULTS

N-ANF showed the closest correlations to clinical and echocardiographic measures of heart failure severity, e.g. NYHA functional class, furosemide dose, exercise tolerance, systolic and diastolic function. Plasma norepinephrine, dopamine and renin activity decreased after 3 months on both treatments, in contrast to a small increase in NPY-LI which was greater (by 3.9 pmol/l, 95% CI 1.2-6.6) in the metoprolol group. N-ANF increased on metoprolol, and decreased on xamoterol (difference: 408 pmol/l, 95% CI 209-607). Increase above median of NPY-LI (>25.2 pmol/l, odds ratio 2.8, P=0.0050) and N-ANF (>1043 pmol/l, odds ratio 2.8, P=0.0055) were related to long term (mean follow-up 6.8 years) cardiovascular mortality.

CONCLUSIONS

Decreased neurohormonal activity, reflecting both the sympathetic nervous system and the renin-angiotensin system, was found 3 months after an acute myocardial infarction with heart failure treated with beta-receptor antagonists. The small increase in NPY-LI may suggest increased sympathetic activity or reduced clearance from plasma. The observed changes of N-ANF may be explained by changes in cardiac preload, renal function, and differences in beta-receptor mediated inhibition of atrial release of N-ANF. NPY-LI, and N-ANF at discharge were related to long term cardiovascular mortality.

Effect of metoprolol CR/XL on exercise tolerance in chronic heart failure - a substudy to the MERIT-HF trial

BACKGROUND

Beta-blockade usually causes a slight reduction in exercise capacity among healthy subjects, while more variable results have been observed in chronic heart failure (CHF), probably related to patients studied, methods and agent used. The effect of metoprolol controlled release/extended release (CR/XL) on peak oxygen uptake (peak VO(2)) in this patient population has not previously been investigated.

AIMS

We examined the effect of long-term treatment with the selective beta(1)-receptor blocker metoprolol CR/XL once daily on exercise capacity in patients with CHF.

METHODS

Ninety-four patients (70 males and 24 females; mean age 63.6+/-10.6 years) with chronic symptomatic heart failure in New York Heart Association (NYHA) functional class II-IV, and with ejection fraction <or=40%, stabilized on optimum standard therapy were randomized to metoprolol CR/XL or placebo in a double-blind trial. Exercise capacity was evaluated by peak VO(2) at baseline, after 3 months and at the end of study (mean follow-up 11.4+/-0.4 months).

RESULTS

Compared with placebo metoprolol CR/XL produced a significant decrease in heart rate by 11 beats/min at rest and 18 beats/min at peak exercise. There was a tendency for a temporal decline in peak VO(2) after 3 months of therapy in both groups, but altogether peak VO(2) remained unchanged from baseline with no difference between the groups at 1 year.

CONCLUSIONS

In patients with moderate to severe CHF, 11.4 months of beta(1)-blockade with metoprolol CR/XL had no effect on exercise capacity when compared with placebo or baseline.

Beta-blocking in heart failure patients. Balancing the evidence

Evidence for the effectiveness of beta-blockers in the management of patients with heart failure is now compelling with a database of over 13000 patients enrolled in randomised prospective placebo-controlled clinical trials. However this therapy remains vastly underused in clinical practice. The different points challenging the widespread use beta blockade agents in the routine treatment in heart failure are presented and discussed. After a review of the potential mechanism hypothesised behind the benefits of beta-blockers in heart failure, the controversial effects on the haemodynamics, exercise tolerance, hospitalisation and mortality are underlined.

[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.

Beta-blocker therapy in heart failure

beta-blocker therapy in heart failure offers the possibility of arresting or reversing the progressive deterioration in this clinical syndrome. While the mechanism is unclear, improvement in cardiac function has been apparent in virtually every study. Clinical results have shown less consistent improvement. Decrease in hospitalization has been noted, but large-scale clinical trials are underway to assess the effect of beta-blockers on mortality.

Neurohormonal activation, oxygen free radicals, and apoptosis in the pathogenesis of congestive heart failure

A variety of pathophysiologic processes are activated in patients with congestive heart failure (CHF), and some of these have been implicated in the progression of the disease. The most important processes to be activated in CHF are the neurohormonal systems, which include the renin-angiotensin system, the sympathetic nervous system, and the endothelin system. In addition to the neurohormonal systems, the formation of reactive oxygen free radicals is increased in patients with CHF. It has been postulated that stimulation of neurohormonal pathways and the formation of oxygen free radicals ultimately lead to the activation of a family of transcription factors that are involved in cardiac remodeling, which is a hallmark of CHF. In addition, the formation of oxygen free radicals has been implicated in the process of apoptosis or programmed cell death, which may be responsible for a continued loss of myocardial cells, resulting in the progressive decrease in left ventricular function that occurs over time in patients with CHF. Carvedilol is a multiple-action neurohormonal antagonist that is effective in slowing the progression of CHF. In double-blind, placebo-controlled clinical trials, carvedilol decreased mortality by 65% (p <0.001) and significantly reduced hospitalization. Carvedilol is a nonselective beta-blocker and vasodilator, the latter activity resulting from alpha1-adrenoceptor blockade. The hemodynamic responses produced by carvedilol result primarily from the blockade of beta1-, beta2-, and alpha1-adrenoceptors. Carvedilol reduces total peripheral vascular resistance and preload without significantly compromising cardiac output or eliciting reflex tachycardia. Carvedilol is also a potent antioxidant that may protect the myocardium from damage produced by oxygen radicals and, as a consequence of its antioxidant activity, carvedilol also inhibits apoptosis in the myocardium. The ability of carvedilol to inhibit apoptosis in the heart may be responsible, in part, for the ability of the drug to reduce mortality and to inhibit the progression of CHF.

The effects of chronic, sustained-release moxonidine therapy on clinical and neurohumoral status in patients with heart failure

AIMS

Congestive heart failure (CHF) is characterized by elevated plasma norepinephrine (PNE) associated with a poor prognosis. Moxonidine selectively stimulates medullary imidazoline receptors which centrally inhibit sympathetic outflow and potently suppress levels of circulating PNE. This study was designed to evaluate the effects of central sympathetic inhibition on clinical and neurohumoral status in patients with CHF.

METHODS AND RESULTS

This study evaluated 25 patients (age=69+/-7 years, 20 males) with symptomatic CHF (NYHA II-III), stabilized on standard therapy. The mean ejection fraction was 28+/-7% at baseline. Patients were titrated in a double-blind fashion to 11 weeks of oral therapy with placebo (n=9) or sustained-release (SR) moxonidine 0.9 mg bid (n=16). Clinical and neurohumoral status were evaluated at baseline, on chronic therapy at the target dose, and during cessation of therapy. All patients completed the trial and reached the target dose. Dry mouth, symptomatic hypotension, and asthenia were more frequent in the moxonidine SR-treated group. PNE was substantially reduced after 6 weeks at the maximum dose (0.9 mg bid) by 50% vs. placebo (P<0. 0005). A reduction in 24-h mean heart rate (P<0.01) was correlated to the reduction in PNE (r=0.70, P<0.05). A 36% increase in the standard deviation of normal-to-normal intervals (SDNN) was observed in the moxonidine SR group vs. a 2% decrease for placebo (P=0.06); for the root mean square of successive differences (rMSSD), there was a 21% increase for moxonidine SR vs. a 19% decrease for placebo (P<0.05). Abrupt cessation of chronic therapy resulted in substantial increases in PNE, blood pressure, and heart rate.

CONCLUSIONS

Chronic therapy with a sustained-release formulation of moxonidine in patients with CHF was well tolerated, with substantial and sustained reductions in PNE. The tachyarrhythmias were attenuated, with evidence of improved autonomic tone. Due to the observed effects following moxonidine discontinuation, tapering of therapy is recommended.

MIC trial: metoprolol in patients with mild to moderate heart failure: effects on ventricular function and cardiopulmonary exercise testing

Beta-blocker therapy results in a functional benefit in patients with heart failure (CHF) due to idiopathic dilated cardiomyopathy (DCM). This study assessed if similar effects were observed in patients with ischemic heart disease (CAD), NYHA II-III after 6 months of therapy with metoprolol.

METHODS AND RESULTS

Fifty-two patients with CHF secondary to DCM (26 patients) and CAD (26 patients) and a left ventricular ejection fraction (EF)<40% were enrolled in the placebo-controlled study. The study medication was titrated over 6 weeks, the mean final dosage was 135 mg/day. Three patients died due to cardiogenic shock, two received placebo and one metoprolol. Eight patients did not complete the study due to non-compliance. Metoprolol significantly reduced heart rate at rest and after submaximal and maximal exercise. Vo(2)-max and Vo(2)-AT as well as the 6-min walk test improved significantly after metoprolol treatment. There was a significant increase in EF at rest (27.3-35. 2%), submaximal (28.5-37.7%) and maximal exercise (28.7-40.9%) in the metoprolol-treated patients. No differences were found between patients with CAD and DCM. We also observed reduced left ventricular volumes.

CONCLUSION

The additional therapy with metoprolol improved cardiac function and the cardiopulmonary exercise capacity in patients with CHF.

Effects of metoprolol CR in patients with ischemic and dilated cardiomyopathy : the randomized evaluation of strategies for left ventricular dysfunction pilot study

BACKGROUND

Metoprolol provides clinical benefits in patients with congestive heart failure (CHF). In this study, we investigated the effects of controlled-release metoprolol (metoprolol CR) on clinical status, on left ventricular (LV) volumes and function, and on neurohumoral activation in a large number of patients with CHF of mixed causes.

METHODS AND RESULTS

Four hundred twenty-six patients with symptomatic CHF were randomized to receive metoprolol CR or placebo for 24 weeks. Metoprolol CR did not affect 6-minute walk distance, New York Heart Association functional class, or quality of life. However, there was a significant improvement in measures of LV function with an attenuation in the increase in LV end-diastolic (+23+/-65 mL [placebo] versus +6+/-61 mL, P=0.01) and LV end-systolic (+19+/-55 mL [placebo] versus -2+/-51 mL, P<0.001) volumes after 24 weeks of therapy. LV ejection fraction was unchanged (-0.05% or -0.005) in the placebo group but increased by 2. 4% in the metoprolol CR-treated patients (P=0.001). Patients receiving metoprolol CR had a greater decrease in angiotensin II (P=0.036) and renin (P=0.032) levels but an increase in N-terminal atrial natriuretic peptide and brain natriuretic peptide levels (P<0. 01). There were fewer deaths in the group receiving beta-blockers (3. 4% versus 8.1%), and there was a similar number of patients experiencing the composite outcomes of death or any hospitalization.

CONCLUSIONS

When added to ACE inhibitors, angiotensin II receptor antagonists, or both, the use of metoprolol CR improves ventricular function, reduces activation of the renin-angiotensin systems, and results in fewer deaths.

Hemodynamic comparison of twice daily metoprolol tartrate with once daily metoprolol succinate in congestive heart failure

OBJECTIVES

To compare the hemodynamic effects of twice daily metoprolol tartrate (MT) and once daily metoprolol succinate (MS) in congestive heart failure patients.

BACKGROUND

Adverse hemodynamic effects with MT demonstrated during initiation persist with drug readministration during chronic therapy.

METHODS

Patients were randomly assigned to 6.25 mg MT or 25 mg MS orally and the dose was gradually increased to a target of 50 mg twice a day or 100 mg once a day, respectively. Hemodynamic measurements were obtained at baseline and after three months of therapy--both before and after drug readministration.

RESULTS

Long term metoprolol therapy produced significant functional, exercise and hemodynamic benefits with no difference in response between either metoprolol preparation in the 27 patients (MT [14], MS [13]). When full dose metoprolol was readministered during chronic therapy, there were parallel adverse hemodynamic effects in both drug groups. Cardiac index decreased by 0.6 liters/min/m2 (p < 0.0001) with MT and by 0.5 liters/min/m2 (p < 0.0001) with MS. Systematic vascular resistance increased by 253 dyne-sec-cm(-5) (p < 0.001) with MT and by 267 dyne-sec-cm(-5) (p < 0.0005) with MS. Stroke volume index decreased by 7.0 ml/m2 (p < 0.0005) with MT and by 6.5 ml/m2 (p < 0.0001) with MS, while SWI decreased by 6.2 g-m/m2 (p < 0.0005) with MT and by 6.0 g-m/m2 (p < 0.001) with MS.

CONCLUSION

Metoprolol tartrate and MS produce similar hemodynamic and clinical effects acutely and chronically despite the fourfold greater starting dose of MS used in this study. A more rapid initiation with readily available starting doses of MS may offer distinct advantages compared with MT in treating chronic heart failure patients with beta-adrenergic blocking agents.

Beta-adrenergic blocker mortality trials in congestive heart failure

Many of the current discussions of beta-adrenergic blocker therapy in patients with congestive heart failure have used fairy tales to describe the evolution of this treatment from contraindication to standard of care. This article reviews the early studies that initiated this revolution in heart failure therapy and discusses the major mortality trials that have demonstrated that these agents improve survival and limit the progression of congestive heart failure. These major trials have used 1 of 4 beta blockers (metoprolol, bisoprolol, carvedilol, or bucindolol) in varying study designs with different patient populations. Each trial had different objectives and limitations, and these are described in the context of their impact on proving a survival benefit. In addition, the specific effect of beta-blocker therapy on sudden death in patients with heart failure is briefly discussed. The weight of these trials suggests that beta-adrenergic blocker therapy can save 1 life of every 35 patients treated in patients with mild-to-moderate heart failure. The data are compelling and the techniques for "starting low and going slow" with titrations have been well documented.

Sympathetic activation and the role of beta-blockers in chronic heart failure

Chronic heart failure (CHF) is associated with activation of the sympathetic nervous system. This activation provides short term haemodynamic support to the failing myocardium, but may be deleterious over longer periods as chronic catecholamine excess appears to contribute to disease progression and increased mortality in this condition. Therefore, blockade of sympathetic activation represents a logical, if somewhat counter-intuitive, approach to the management of the patient with systolic CHF. Pharmacological approaches to blockade of this system include inhibition of central sympathetic outflow (using central sympatholytics, e.g. rilmenidine, moxonidine), blockade of the catecholamine biosynthetic pathway (dopamine beta hydroxylase antagonists) and blockade of the cardiac effects of sympathetic activation (beta-adrenoceptor blocking agents). Beta-blockers have now been extensively studied in patients with symptomatic CHF of the New York Heart Association (NYHA) Class II and III severity. Provided beta-blocker therapy is carefully up-titrated from sub-therapeutic doses and given for at least three to four months, these agents have been associated with favourable long term haemodynamic, functional and mortality outcomes. Furthermore, beta-blockers delay disease progression in CHF by reversing the pathological myocardial remodelling process that accompanies the disease. Non-selective beta-adrenoceptor blocking drugs appear to be of particular benefit in CHF therapy. Myocardial beta2 receptors are down-regulated to a lesser extent than beta1 receptors in CHF, therefore blockade of the beta2 receptor sub-type may assume greater importance in inhibiting the deleterious effects of sympathetic activation on the myocardium in this disease. Newer agents that possess additional vasodilator properties (carvedilol, bucindolol, nebivolol) may be useful in overcoming the initial negative inotropy of the beta-blocking component of the drug, however, it is unlikely that vasodilation contributes greatly to long term clinical benefits. Drugs such as carvedilol are also anti-oxidant, anti-proliferative and have anti-endothelin actions; the clinical significance of these properties is yet to be determined. Unanswered questions remain regarding the use of beta-blockers in heart failure. Ongoing studies are further examining mechanisms underlying the clinical benefits of these agents as well as their therapeutic potential in NYHA Class IV patients, heart failure post-myocardial infarction and patients with asymptomatic left ventricular dysfunction.

The circulating renin-angiotensin system during treatment with metoprolol or captopril in patients with heart failure due to non-ischaemic dilated cardiomyopathy

OBJECTIVE

To investigate the effects of beta-blocker (metoprolol) or angiotensin-converting enzyme inhibitor (captopril) treatment on neurohormonal function in a randomized prospective study on patients with heart failure due to dilated cardiomyopathy.

PATIENTS

Fifty-four patients (42 men and 12 women, mean age 50 years) were studied. There were three patients in NYHA (New York Heart Association) functional class I, 32 patients in class II and 19 patients in class III.

METHODS

Measurements of plasma renin activity (PRA). plasma angiotensin II (A II) concentration and plasma atrial natriuretic peptide (ANP) concentration were made at rest and also in a subgroup (n = 32) during exercise. The urinary excretion of aldosterone was also determined. Investigations were performed at baseline, and after 3 and 6 months. Therapy was then stopped and the patients were re-investigated 1 month thereafter.

RESULTS

The mean level of PRA was normal at baseline, reduced during therapy with metoprolol, and increased during therapy with captopril. The mean plasma concentration of A II was reduced during exercise and there was a trend towards a reduction even at rest in the metoprolol group, but not in the captopril group. The urinary excretion of aldosterone decreased in both groups. The mean plasma concentration of ANP was elevated at baseline and declined during exercise in the metoprolol group.

CONCLUSION

In patients with dilated cardiomyopathy and only a partly activated renin-angiotensin system, both metoprolol and captopril reduced urinary excretion of aldosterone. Furthermore, metoprolol suppressed the exercise-induced increase in ANP, suggesting a favourable effect on ventricular performance.

Cellular and molecular remodeling in a heart failure model treated with the beta-blocker carteolol

Broad-breasted white turkey poults fed furazolidone developed dilated cardiomyopathy (DCM) characterized by ventricular dilatation, decreased ejection fraction, beta1-receptor density, sarcoplasmic reticulum (SR) Ca2+-ATPase, myofibrillar ATPase activity, and reduced metabolism markers. We investigated the effects of carteolol, a beta-adrenergic blocking agent, by administrating two different dosages (0.01 and 10.0 mg/kg) twice a day for 4 wk to control and DCM turkey poults. At completion of the study there was 59% mortality in the nontreated DCM group, 55% mortality in the group treated with the low dose of carteolol, and 22% mortality in the group treated with the high dose of carteolol. Both treated groups showed a significant decrease in left ventricle size and significant restoration of ejection fraction and left ventricular peak systolic pressure. Carteolol treatment increased beta-adrenergic receptor density, and the high carteolol dose restored SR Ca2+-ATPase and myofibrillar ATPase activities, along with creatine kinase, lactate dehydrogenase, aspartate transaminase, and ATP synthase activities, to normal. These results show that beta-blockade with carteolol improves survival, reverses contractile abnormalities, and induces cellular remodeling in this model of heart failure.

Beta blocker treatment in heart failure

The sympathetic nervous system occupies a prominent role in heart failure both as a marker of severity of disease and also as an important factor in its progression. Beta blocker therapy, once thought heretical in heart failure, has consistently improved cardiac function and slowed progression of disease. Large clinical trials of mild to moderate heart failure show improved survival as well as reduction in hospitalization. Beta blockers now have stronger data in heart failure than converting enzyme inhibitors, and should be considered standard therapy in mild-moderate heart failure. Ongoing trials are addressing beta blocker therapy in advanced heart failure and comparisons between agents.

Medical therapy of chronic heart failure. Role of ACE inhibitors and beta-blockers

Heart failure has long been considered to have a progressive downhill course leading inexorably to an early demise. This course often occurs silently, in the absence of any obvious cardiac insults. The reason for this is a combination of cell loss, myocyte dysfunction, impaired energetics, and pathologic remodeling of the chamber. Improved clinical outcome should result from strategies that reduce the biologic signals responsible for myocyte growth, dysfunction, and loss and chamber remodeling. Clinicians should no longer attempt to treat chronic heart failure with pharmacologic growth and remodeling process. In time, it may be possible for the clinician to view the treatment of heart failure largely as a matter of improving the biologic function of the myocardium.

Ejection fraction improvement by beta-blocker treatment in patients with heart failure: an analysis of studies published in the literature

Because ejection fraction (EF) is one of the most important predictors of survival in patients with left ventricular (LV) dysfunction and because Packer showed a large reduction in mortality figures with carvedilol, in contrast to former studies with bisoprolol and metoprolol, we investigated if this difference in survival may be related to a difference in improvement of LV function by different beta-blockers. We searched the MEDLINE database and all reference lists of articles obtained through the search for the relation between beta-blocker treatment and improvement in EF. Forty-one studies met the criteria and we added two of our own studies. Four hundred and fifty-eight patients were treated with metoprolol with a mean follow-up of 9.5 months and a mean increase in EF of 7.4 EF units. One thousand thirty patients were treated with carvedilol with a mean follow up of 7 months and a mean increase in EF of 5.7 EF units. One hundred ninety-nine patients were treated with bucindolol with a mean follow-up of 4 months and a mean increase in EF of 4.6 EF units. Several small studies with nebivolol, atenolol, and propranolol were also studied and, when combined, the mean increase in EF was 8.6 EF units. When patients with idiopathic and ischemic cardiomyopathies were compared, the average increase in EF units was 8.5 vs. 6.0, respectively. The use of beta-blocker treatment in heart failure patients, irrespective of the etiology, improved LV function in almost all studies and it appears that the differences among beta-blockers and among etiologies is small and probably insignificant. However, there is a difference in survival rate when the various beta-blockers are compared, suggesting that mechanisms other than improvement of LV function by beta-blockers are responsible for the difference in survival.

Use of carvedilol in chronic heart failure: challenges in therapeutic management

In controlled trials, long-term treatment of patients with chronic heart failure with beta-blockers improves symptoms, slows progression of disease, and reduces morbidity and mortality rates. However, in some patients the introduction of therapy can be associated with a period of clinical instability, including risks of fluid retention, hypotension, and bradycardia. Appropriate patient selection and optimization of background therapy can minimize the risk during the introduction of therapy. With vigilance for early signs of clinical deterioration and appropriate adjustment of background medications, the care of most patients exhibiting clinical instability can be successfully managed so the patient is able to continue with the long-term therapy, a prerequisite to realizing beneficial effects. With the initiation of carvedilol, any evidence of fluid retention warrants a prompt increase in the diuretic dosage, and in more pronounced cases the carvedilol dose may need to be reduced or interrupted. In contrast, symptoms of hypotension (most commonly dizziness) generally resolve without intervention, although persistent problems may necessitate adjusting the timing of dose administration or perhaps temporarily reducing the dose of vasodilators or diuretics (the latter with care to avoid fluid retention). Bradycardia should be managed as standard practice would indicate. During long-term treatment, adjustments in beta-blocker dosage may be required in the event of an exacerbation of heart failure. Dosages should be adjusted as would be the case with other heart-failure medications, based on the severity of the clinical decompensation, but with care to minimize abrupt changes unless mandated by the patient's condition and to avoid precipitating ischemia or further deterioration. The occurrence of effects such as these does not necessarily indicate that a patient cannot respond favorably to long-term beta-blockade, but all require understanding, vigilance, and the availability of medical personnel, especially during the introduction of this therapy.

Over 20 years' experience of beta-blockade in heart failure

The use of beta-blocker therapy in heart failure was contraindicated for many years because it was considered to block necessary sympathetic compensatory responses to reduced cardiac function. However, early studies provided promising results in terms of improved symptoms and work capacity and reduced heart size. Small-scale studies have been completed over the past 20 years but until large-scale, long-term, randomized trials were conducted, the potential of beta-blockers in heart failure was not confirmed. The results of randomized trials published to date have included over 3,000 patients and the results show improvements in left ventricular function and heart rate. Significant improvements in New York Heart Association classification were also shown. Although no conclusive effect on mortality was shown, the first Cardiac Insufficiency Bisoprolol Study (CIBIS) indicated a trend toward improved survival during long-term treatment with bisoprolol. Ongoing studies have been specifically designed to investigate the effects of beta-blockers on survival. One of these trials, CIBIS II, which was terminated early in 1998 because of a positive effect on survival, is expected to report in late summer 1998. Such trials will also examine the different mechanisms of action of beta-blockers in heart failure and the influence of causes on the effects of beta-blockade.

Innovations in the pharmacologic management of heart failure

Improved understanding of the pathophysiologic course of heart failure has led to many advances in pharmacologic therapy. Angiotensin-converting enzyme inhibitors represent the first effort at targeting neurohormonal activation in chronic heart failure. More recently, beta-adrenergic receptor antagonists have been shown effective in blocking chronic sympathetic nervous system activation. The roles of digoxin and the newer, vasoselective calcium channel blockers in heart failure have been better defined. Other agents targeting the neurohormonal system are under investigation. These include angiotensin-receptor antagonists, aldosterone inhibitors, and endothelin antagonists. Experience with phosphodiesterase inhibitors and adrenergic agents has confirmed the importance of neurohormonal activation in progression of heart failure. Despite angiotensin-converting enzyme inhibitor, diuretic, and digoxin therapy, mortality in heart failure remains high. Careful manipulation of the neurohormonal response to heart failure holds promise for altering the course of the disease.

A review of why and how we may use beta-blockers in congestive heart failure

The history of the use of beta-blockers for congestive heart failure, beginning with the innovative seminal study by the Swedish group in 1975 to studies in 1995, is reviewed and shows that almost all trials favored the use of beta-blockers. They tended to demonstrate an increase in ejection fraction, a decrease in left ventricular mass, and in some studies, even a decrease in mortality. Even after the introduction of angiotensin-converting enzyme inhibitors, additional improvement in function and mortality was observed. Patients with nonischemic dilated cardiomyopathy derived more benefit from beta-blockers than did patients with ischemic cardiomyopathy. Least likely to benefit were patients treated for <2 months, patients with alcoholic cardiomyopathy, and those with marked intercellular fibrosis. Although the starting dose of metoprolol, the most common beta-blocker used, may have to be as low as 2.5 mg/d, mortality analysis failed to show a decrease in sudden death unless the dose was raised to about 300 mg/d, a dose at which beta-selectivity is generally not expected to be present. The non-beta-specific bucindolol or carvedilol may ultimately be preferred to metoprolol because they are better tolerated initially due to a slight vasodilatation effect. Initial studies with carvedilol showed remarkable promise in reducing mortality. However, these agents cannot yet be said to have been studied adequately.

[Cost effectiveness of bisoprolol in heart failure. Economic evaluation of the Cardiac Insufficiency Bisoprolol Study (CIBIS) for Germany]

BACKGROUND

The Cardiac Insufficiency Bisoprolol Study (CIBIS) demonstrates that, for patients with heart failure of different etiologies, the administration of the beta(1)-adrenoceptor blocker bisoprolol adjuvant to the standard therapy leads to a significant avoidance of hospital admissions.

PHARMACOECONOMIC EVALUATION

The results of the CIBIS were evaluated pharmacoeconomically for the Federal Republic of Germany, and were restricted to direct costs only. The costs of bisoprolol medication and in-patient treatment of heart failure were considered, the latter forming the major part of costs incurred.

CONCLUSION

Adjunctive therapy with bisoprolol is not only clinically beneficial to the patient with heart failure, but also economically advantageous.

Effect of beta-blockade on mortality in patients with heart failure: a meta-analysis of randomized clinical trials

OBJECTIVES

We sought to evaluate the current evidence for an effect of beta-blockade treatment on mortality in patients with congestive heart failure (CHF).

BACKGROUND

Although numerous small studies have suggested a benefit with beta-blocker therapy in patients with heart failure, a clear survival benefit has not been demonstrated. A recent combined analysis of several studies with the alpha- and beta-adrenergic blocking agent carvedilol demonstrated a significant survival advantage; however, the total number of events was small. Furthermore, it is unclear if previous studies with other beta-blockers are consistent with this finding.

METHODS

Randomized clinical trials of beta-blockade treatment in patients with CHF from January 1975 through February 1997 were identified using a MEDLINE search and a review of reports from scientific meetings. Studies were included if mortality was reported during 3 or more months of follow-up.

RESULTS

We identified 35 reports, 17 of which met the inclusion criteria. These studies included 3,039 patients with follow-up ranging from 3 months to 2 years. Beta-blockade was associated with a trend toward mortality reduction in 13 studies. When all 17 reports were combined, beta-blockade significantly reduced all-cause mortality (random effect odds ratio [OR] 0.69, 95% confidence interval [CI] 0.54 to 0.88). A trend toward greater treatment effect was noted for nonsudden cardiac death (OR 0.58, 95% CI 0.40 to 0.83) compared with sudden cardiac death (OR 0.84, 95% CI 0.59 to 1.2). Similar reductions in mortality were observed for patients with ischemic (OR 0.69, 95% CI 0.49 to 0.98) and nonischemic cardiomyopathy (OR 0.69, 95% CI 0.47 to 0.99). The survival benefit was greater for trials of the drug carvedilol (OR 0.54, 95% CI 0.36 to 0.81) than for noncarvedilol drugs (OR 0.82, 95% CI 0.60 to 1.12); however, the difference did not reach statistical significance (p = 0.10).

CONCLUSIONS

Pooled evidence suggests that beta-blockade reduces all-cause mortality in patients with CHF. Additional trials are required to determine whether carvedilol differs in its effect from other agents.

Beta-blocker use in systolic heart failure and dilated cardiomyopathy

Statistics regarding long-term survival for patients with heart failure are discouraging today. Converting enzyme inhibitors have produced a modest effect on mortality. beta-Blockers may be the next addition to standard therapy for heart failure because they generate consistent improvements in hemodynamic factors, symptom scores, and submaximal exercise tolerance in randomized, controlled clinical trials. They augment ejection fraction, reduce heart volume, and consistently lower neurohormonal activation as reflected by plasma norepinephrine levels. Trials with carvedilol and bisoprolol suggest an effect on mortality similar to that with converting enzyme inhibitor trials. Future studies, especially the beta-blocker Evaluation Survival Trial (BEST), with mortality as the main end point should elucidate the degree of effect on mortality further.

Beta-adrenergic blocking agents in the treatment of congestive heart failure: mechanisms and clinical results

Congestive heart failure is a major public health problem in Western countries. Despite current treatment including angiotensin converting enzyme inhibitors, mortality and morbidity remain high. The sympathetic nervous system is markedly activated in heart failure, and inhibition of this system with the beta-adrenergic blocking agents may provide further benefit. Several clinical trials involving over 3,000 patients have shown that beta-blocker therapy improves left ventricular function in patients with heart failure. However, the effects of such therapy on symptoms and exercise tolerance have been variable. Recent reports have suggested that survival is improved with the beta-blocker carvedilol. Large-scale, long-term clinical trials are required to confirm these findings and to clearly define the role of this promising therapy for patients with heart failure.

Hemodynamic predictors of early intolerance and long-term effects of propranolol in dilated cardiomyopathy

BACKGROUND

Fifty-six patients with dilated cardiomyopathy (DCM) (aged 14-68 years) and background therapy of angiotensin-converting enzyme inhibitors, diuretics, and digoxin were given an initial challenge of propranolol in gradually increasing doses. These patients were studied noninvasively and hemodynamically and subjected to right ventricle biopsy.

METHODS AND RESULTS

Forty-four patients tolerated propranolol and received the drug for 6 months; 12 patients deteriorated after starting the drug with worsening of congestive heart failure and/or hypotension. The patients who did not tolerate propranolol had higher left ventricular end-diastolic dimension (73 +/- 8 vs 66 +/- 8 mm, P < .05), and severe mitral regurgitation was more common. Hemodynamically these patients had higher heart rate, right ventricular end-diastolic pressure, mean pulmonary artery pressure, mean pulmonary artery wedge pressure, and left ventricular end-diastolic pressure (102 +/- 16 vs 89 +/- 12 beats/min, 15 +/- 7 vs 9 +/- 4, 39 +/- 16 vs 31 +/- 12, 28 +/- 8 vs 21 +/- 8, 28 +/- 8 vs 22 +/- 8 mmHg, respectively, P < .01). These patients had a significantly lower cardiac index (1.9 +/- 0.6 vs 2.5 +/- 0.6 L/min/m2, P < .01). Forty patients completed 6 months follow-up evaluation and were further subjected to repeat noninvasive and hemodynamic study. There was a significant improvement in New York Heart Association class, cardiothoracic ratio, and left ventricular end-diastolic dimension (68% vs 62%, 66 +/- 8 vs 62 +/- 7 mm, respectively, P < .01), while the ejection fraction (EF) rose from 23 to 35% (P < .001). Hemodynamically, there was a significant decrease in heart rate, right ventricular end-diastolic pressure, mean pulmonary artery pressure, mean pulmonary artery wedge pressure, and left ventricular end-diastolic pressure (91 +/- 14 vs 71 +/- 5 beats/min, 9 +/- 4 vs 5 +/- 3, 32 +/- 11 vs 22 +/- 7, 25 +/- 9 vs 17 +/- 8, 21 +/- 7 vs 14 +/- 4 mmHg, P < .05). The cardiac index rose from 2.3 +/- 0.6 to 3.2 +/- 0.7 L/min/m2 (P < .01).

CONCLUSIONS

Propranolol in dilated cardiomyopathy is associated with significant intolerance. Those who tolerate propranolol seem to have long-term beneficial effects. This study is limited as it is uncontrolled and nonrandomized.

Double-blind, placebo-controlled study of the effects of carvedilol in patients with moderate to severe heart failure. The PRECISE Trial. Prospective Randomized Evaluation of Carvedilol on Symptoms and Exercise

BACKGROUND

Carvedilol has improved the symptomatic status of patients with moderate to severe heart failure in single-center studies, but its clinical effects have not been evaluated in large, multicenter trials.

METHODS AND RESULTS

We enrolled 278 patients with moderate to severe heart failure (6-minute walk distance, 150 to 450 m) and a left ventricular ejection fraction < or = 0.35 at 31 centers. After an open-label, run-in period, each patient was randomly assigned (double-blind) to either placebo (n = 145) or carvedilol (n = 133; target dose, 25 to 50 mg BID) for 6 months, while background therapy with digoxin, diuretics, and an ACE inhibitor remained constant. Compared with placebo, patients in the carvedilol group had a greater frequency of symptomatic improvement and lower risk of clinical deterioration, as evaluated by changes in the NYHA functional class (P = .014) or by a global assessment of progress judged either by the patient (P = .002) or by the physician (P < .001). In addition, treatment with carvedilol was associated with a significant increase in ejection fraction (P < .001) and a significant decrease in the combined risk of morbidity and mortality (P = .029). In contrast, carvedilol therapy had little effect on indirect measures of patient benefit, including changes in exercise tolerance or quality-of-life scores. The effects of the drug were similar in patients with ischemic heart disease or idiopathic dilated cardiomyopathy as the cause of heart failure.

CONCLUSIONS

These findings indicate that, in addition to its favorable effects on survival, carvedilol produces important clinical benefits in patients with moderate to severe heart failure treated with digoxin, diuretics, and an ACE inhibitor.

Medical therapy can improve the biological properties of the chronically failing heart. A new era in the treatment of heart failure

Myocardial failure has been considered to be an irreversible and progressive process characterized by ventricular enlargement, chamber geometric alterations, and diminished pump performance. However, more recent evidence has suggested that certain types of medical therapy may lead to retardation and even reversal of the cardiomyopathic process. In the failing heart, long-term neurohormonal/autocrine-paracrine activation results in abnormalities in myocyte growth, energy production and utilization, calcium flux, and receptor regulation that produce a progressively dysfunctional, mechanically inefficient heart. Interventions such as ACE inhibition and beta-blockade result in a reduction in the harmful long-term consequences of neurohormonal/autocrine-paracrine effects and retard the progression of left ventricular dysfunction or ventricular remodeling. Furthermore, in subjects with idiopathic dilated or ischemic cardiomyopathy, antiadrenergic therapy with beta-blocking agents appears to be able to partially reverse systolic dysfunction and ventricular remodeling. Although the precise mechanisms underlying this latter effect have not yet been elucidated, the general mechanism appears to be via improvement in the biological function of the cardiac myocyte. Such an improvement in the intrinsic defect(s) responsible for myocardial failure will likely translate into important clinical benefits.

Effects of beta-blockade with bisoprolol on heart rate variability in advanced heart failure: analysis of scatterplots of R-R intervals at selected heart rates

The effect of beta-blockade on heart-rate variability was assessed at different heart rates in 52 patients with heart failure included in the randomized, placebo-controlled, Cardiac Insufficiency Bisoprolol Study (CIBIS). Scatterplots of R-R intervals display beat-to-beat variability by plotting each R-R interval against the preceding interval. Scatterplot dispersion at different R-R intervals provides a measure of beat-to-beat heart-rate variability at different heart rates. A 24-hour Holter tape was performed at baseline and after 2 months of treatment with bisoprolol or matched placebo. Geometric measurements of scatterplots were used to determine beat-to-beat dispersion for different R-R intervals. Bisoprolol and placebo groups were well matched at base-line. After 2 months of treatment, bisoprolol significantly increased beat-to-beat variability at the longest R-R intervals (p < 0.05); however, there was no change in scatterplot dispersion at the shortest R-R intervals. This suggests that beta-blockade increases parasympathetic or decreases sympathetic tone or both in heart failure patients only at the slowest heart rates.