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

Pleural Effusion and Invasive Hemodynamic Measurements in Advanced Heart Failure

BACKGROUND

Pleural effusion is present in 50% to 80% of patients with acute heart failure, depending on image modality. We aim to describe the association between the presence and size of pleural effusion and central hemodynamics, including pulmonary capillary wedge pressure (PCWP) in an advanced heart failure population.

METHODS

An observational, cross-sectional study in a cohort of patients with advanced heart failure (left ventricular ejection fraction ≤45%) who underwent right heart catheterization at The Department of Cardiology at Copenhagen University Hospital, Rigshospitalet, Denmark, between January 1, 2002 and October 31, 2020. The presence and size of pleural effusion were determined by a semiquantitative score of chest x-rays or computed tomography scans performed within 2 days of right heart catheterization.

RESULTS

In 346 patients (50±13 years; 78% males) with median left ventricular ejection fraction of 20% (15-25), we identified 162 (47%) with pleural effusion. The pleural effusion size was medium in 38 (24%) and large in 30 (19%). Patients with pleural effusion had a 4.3 mm Hg (2.5-6.1) higher PCWP and 2.4 mm Hg (1.2-3.6) higher central venous pressure (P<0.001 for both). Patients with a medium/large pleural effusion had statistically significantly higher filling pressures than patients with a small effusion. Higher PCWP (odds ratio [OR], 1.06 [1.03-1.10]) and central venous pressure (OR, 1.09 [1.05-1.15]) were associated with pleural effusion in multivariable logistic regression adjusted for age, sex, and heart failure medications (P<0.001 for both). In a subgroup of 204 (63%) patients with serum albumin data, PCWP (OR, 1.06 [1.01-1.11]; P=0.032), central venous pressure (OR, 1.14 [1.06-1.23]; P<0.001) and serum albumin level (OR, 0.89 [0.83-0.95]; P<0.001) were independently associated with the presence of a medium/large-sized pleural effusion.

CONCLUSIONS

In patients with left ventricular ejection fraction ≤45% undergoing right heart catheterization as part of advanced heart failure work-up, pleural effusion was associated with higher PCWP and central venous pressure and lower serum albumin.

Sex-dependent changes in physical, mental, and quality of life outcomes in metoprolol-treated Chinese chronic heart failure patients

This study assessed sex differences in cardiac and motor functions, quality of life (QoL), and mental status in Chinese chronic heart failure (CHF) patients after metoprolol treatment.This single-center prospective study, conducted from February 2013 to April 2016, included CHF patients (men and women) with resting heart rate (HR) >80 beats/min using metoprolol continuous release tablets. Metoprolol-induced changes in cardiac and motor functions, QoL, and mental status at 1, 3, 6, 9, and 12 months from baseline, within and between the sexes, were analyzed. Descriptive data were represented as counts, percentages, and mean ± standard deviation. Differences at various follow-up periods were compared using repeated measures one-way analysis of variance, followed by post hoc Dunnett's multiple comparison test. Statistical significance was considered at P < .05.Compared with men, women reported significantly higher systolic blood pressure (SBP) (122.28 ± 6.76 vs 125.47 ± 6.67 mm Hg, P < .05) and Veterans Specific Activity Questionnaire score (8.16 ± 0.98 vs 8.47 ± 0.89, P = .05) at 12 months. Men reported higher Hospital Anxiety and Depression Scale scores for depression than women at 1 month (10.27 vs 8.83, P < .05) and for anxiety at 12 months (8.4 vs 7.72, P < .05). Metoprolol significantly decreased HR and Minnesota Living with Heart Failure Questionnaire score in men (64.5 ± 3.13 and 53.7 ± 8.00) and women (65.38 ± 3.32 and 53.85 ± 8.42, respectively). Ejection fraction (%, men: 50.00 ± 4.45, women: 50.72 ± 4.09), cardiac index (L/min/m, men: 2.70 ± 0.25, women: 2.78 ± 0.23), 6-minute walk test distance (m, men: 414.41 ± 20.84, women: 420.34 ± 20.35), and short form-8 questionnaire scores (men: 52.05 ± 1.94, women: 52.19 ± 2.58) increased significantly in both the sexes (P < .001 for all) at 12 months. Copenhagen Burnout Inventory score significantly increased in men (mean score 62.43, P < .05).Metoprolol treatment improves cardiac and motor functions, QoL, and anxiety scores but causes greater depression and burnout in men and women. Sex was seen to affect mental status of CHF patients the most.

Adrenergic Downregulation in Critical Care: Molecular Mechanisms and Therapeutic Evidence

Catecholamines remain the mainstay of therapy for acute cardiovascular dysfunction. However, adrenergic receptors quickly undergo desensitization and downregulation after prolonged stimulation. Moreover, prolonged exposure to high circulating catecholamines levels is associated with several adverse effects on different organ systems. Unfortunately, in critically ill patients, adrenergic downregulation translates into progressive reduction of cardiovascular response to exogenous catecholamine administration, leading to refractory shock. Accordingly, there has been a growing interest in recent years toward use of noncatecholaminergic inotropes and vasopressors. Several studies investigating a wide variety of catecholamine-sparing strategies (eg, levosimendan, vasopressin, β-blockers, steroids, and use of mechanical circulatory support) have been published recently. Use of these agents was associated with improvement in hemodynamics and decreased catecholamine use but without a clear beneficial effect on major clinical outcomes. Accordingly, additional research is needed to define the optimal management of catecholamine-resistant shock.

A Review of the External Validity of Clinical Trials with Beta-Blockers in Heart Failure

BACKGROUND

Beta-blockers (BBs) are the mainstay prognostic medication for all stages of chronic heart failure (CHF). There are many classes of BBs, each of which has varying levels of evidence to support its efficacy in CHF. However, most CHF patients have one or more comorbid conditions such as diabetes, renal impairment, and/or atrial fibrillation. Patient enrollment to randomized controlled trials (RCTs) often excludes those with certain comorbidities, particularly if the symptoms are severe. Consequently, the extent to which evidence drawn from RCTs is generalizable to CHF patients has not been well described. Clinical guidelines also underrepresent this point by providing generic advice for all patients. The aim of this review is to examine the evidence to support the use of BBs in CHF patients with common comorbid conditions.

METHODS

We searched MEDLINE, PubMed, and the reference lists of reviews for RCTs, post hoc analyses, systematic reviews, and meta-analyses that report on use of BBs in CHF along with patient demographics and comorbidities.

RESULTS

In total, 38 studies from 28 RCTs were identified, which provided data on six BBs against placebo or head to head with another BB agent in ischemic and nonischemic cardiomyopathies. Several studies explored BBs in older patients. Female patients and non-Caucasian race were underrepresented in trials. End points were cardiovascular hospitalization and mortality. Comorbid diabetes, renal impairment, or atrial fibrillation was detailed; however, no reference to disease spectrum or management goals as a focus could be seen in any of the studies. In this sense, enrollment may have limited more severe grades of these comorbidities.

CONCLUSIONS

RCTs provide authoritative information for a spectrum of CHF presentations that support guidelines. RCTs may provide inadequate information for more heterogeneous CHF patient cohorts. Greater Phase IV research may be needed to fill this gap and inform guidelines for a more global patient population.

Carvedilol Compared With Metoprolol Succinate in the Treatment and Prognosis of Patients With Stable Chronic Heart Failure: Carvedilol or Metoprolol Evaluation Study

BACKGROUND

β-Blockers exert a prognostic benefit in the treatment of chronic heart failure. Their pharmacological properties vary. The only substantial comparative trial to date-the Carvedilol or Metoprolol European Trial-has compared carvedilol with short-acting metoprolol tartrate at different dose equivalents. We therefore addressed the relative efficacy of equal doses of carvedilol and metoprolol succinate on survival in multicenter hospital outpatients with chronic heart failure.

METHODS AND RESULTS

Four thousand sixteen patients with stable systolic chronic heart failure who were using either carvedilol or metoprolol succinate were identified in the Norwegian Heart Failure Registry and The Heart Failure Registry of the University of Heidelberg, Germany. Patients were individually matched on both the dose equivalents and the respective propensity scores for β-blocker treatment. During a follow-up for 17 672 patient-years, it was found that 304 (27.2%) patients died in the carvedilol group and 1066 (36.8%) in the metoprolol group. In a univariable analysis of the general sample, metoprolol therapy was associated with higher mortality compared with carvedilol therapy (hazard ratio, 1.49; 95% confidence interval, 1.31-1.69; P<0.001). This difference was not seen after multivariable adjustment (hazard ratio, 0.93; 95% confidence interval, 0.57-1.50; P=0.75) and adjustment for propensity score and dose equivalents (hazard ratio, 1.06; 95% confidence interval, 0.94-1.20; P=0.36) or in the propensity and dose equivalent-matched sample (hazard ratio, 1.00; 95% confidence interval, 0.82-1.23; P=0.99). These results were essentially unchanged for all prespecified subgroups.

CONCLUSIONS

In outpatients with chronic heart failure, no conclusive association between all-cause mortality and treatment with carvedilol or metoprolol succinate was observed after either multivariable adjustment or multilevel propensity score matching.

Nebivolol, but not metoprolol, lowers blood pressure in nitric oxide-sensitive human hypertension

Nebivolol, unlike other selective β1-receptor blockers, induces vasodilation attributable to increased NO bioavailability. The relative contribution of this mechanism to the blood pressure (BP)-lowering effects of nebivolol is unclear because it is normally masked by baroreflex buffering. Autonomic failure provides a unique model of hypertension devoid of autonomic modulation but sensitive to the hypotensive effects of NO potentiation. We tested the hypothesis that nebivolol would decrease BP in these patients through a mechanism independent of β-blockade. We randomized 20 autonomic failure patients with supine hypertension (14 men; 69±2 years) to receive a single oral dose of placebo, nebivolol 5 mg, metoprolol 50 mg (negative control), and sildenafil 25 mg (positive control) on separate nights in a double-blind, crossover study. Supine BP was monitored every 2 hours from 8:00 pm to 8:00 am. Compared with placebo, sildenafil and nebivolol decreased systolic BP during the night (P<0.001 and P=0.036, by mixed-effects model, maximal systolic BP reduction 8-hour postdrug of -20±6 and -24±9 mm Hg, respectively), whereas metoprolol had no effect. In a subanalysis, we divided patients into sildenafil responders (BP fall>20 mm Hg at 4:00 am) and nonresponders. Nebivolol significantly lowered systolic BP in sildenafil responders (-44±13 mm Hg) but not in nonresponders (1±11 mm Hg). Despite lowering nighttime BP, nebivolol did not worsen morning orthostatic tolerance compared with placebo. In conclusion, nebivolol effectively lowered supine hypertension in autonomic failure, independent of β1-blockade. These results are consistent with the hypothesis that NO potentiation contributes significantly to the antihypertensive effect of nebivolol.

Endothelial function is unaffected by changing between carvedilol and metoprolol in patients with heart failure--a randomized study

Background

Carvedilol has been shown to be superior to metoprolol tartrate to improve clinical outcomes in patients with heart failure (HF), yet the mechanisms responsible for these differences remain unclear. We examined if there were differences in endothelial function, insulin stimulated endothelial function, 24 hour ambulatory blood pressure and heart rate during treatment with carvedilol, metoprolol tartrate and metoprolol succinate in patients with HF.

Methods

Twenty-seven patients with mild HF, all initially treated with carvedilol, were randomized to a two-month treatment with carvedilol, metoprolol tartrate or metoprolol succinate. Venous occlusion plethysmography, 24-hour blood pressure and heart rate measurements were done before and after a two-month treatment period.

Results

Endothelium-dependent vasodilatation was not affected by changing from carvedilol to either metoprolol tartrate or metoprolol succinate. The relative forearm blood flow at the highest dose of serotonin was 2.42 ± 0.33 in the carvedilol group at baseline and 2.14 ± 0.24 after two months continuation of carvedilol (P = 0.34); 2.57 ± 0.33 before metoprolol tartrate treatment and 2.42 ± 0.55 after treatment (p = 0.74) and in the metoprolol succinate group 1.82 ± 0.29 and 2.10 ± 0.37 before and after treatment, respectively (p = 0.27). Diurnal blood pressures as well as heart rate were also unchanged by changing from carvedilol to metoprolol tartrate or metoprolol succinate.

Conclusion

Endothelial function remained unchanged when switching the beta blocker treatment from carvedilol to either metoprolol tartrate or metoprolol succinate in this study, where blood pressure and heart rate also remained unchanged in patients with mild HF.

Trial registration

Current Controlled Trials NCT00497003

Chronic heart failure: current evidence, challenges to therapy, and future directions

Heart failure (HF) is a complex syndrome characterized by the inability of the heart to maintain a normal cardiac output without elevated intracardiac filling pressures, resulting in signs of pulmonary and peripheral edema and symptoms of dyspnea and fatigue. Central to the management of HF is a multifaceted pharmacological intervention to abate the harmful counter-regulatory effects of neurohormonal activation and avid salt and water retention. Whereas up to 40 years ago HF was managed with diuretics and leaf of digitalis, the cornerstones of therapy for HF patients with systolic dysfunction now include ACE inhibitors or angiotensin II type 1 receptor antagonists (angiotensin receptor blockers), β-adrenoceptor antagonists (β-blockers), and aldosterone antagonists, which have significantly improved survival. However, with the increasing number of beneficial therapies, there are challenges to implementing all of them. Specific cardiomyopathies also merit specific considerations with respect to treatment, and - unfortunately - there is no therapy for HF with preserved left ventricular ejection fraction that has been shown to improve survival. Although mortality has improved in HF, the biggest challenge to treatment lies in addressing the morbidity of this disease, which is now the most common reason for hospital admission in our aged population. As such, there are many therapies that may serve to improve the quality of life of HF patients. Future HF treatment regimens may include direct cellular therapy via hormone and cytokine signaling or cardiac regeneration through growth factors or cell therapy.

Beneficial association of β-blocker therapy on recovery from severe acute heart failure treatment: data from the Survival of Patients With Acute Heart Failure in Need of Intravenous Inotropic Support trial

OBJECTIVES

Beta-blocker therapy is recommended for most patients with chronic heart failure, although such therapy may be discontinued or reduced during hospitalizations. The aim is to determine whether β-blocker use at study entry and/or at discharge has an impact on 31- and 180-day survival.

DESIGN

Survival of Patients With Acute Heart Failure in Need of Intravenous Inotropic Support study was designed as a randomized, double-blind, active-controlled, multi-center study.

SETTING

Multinational.

PATIENTS

A total of 1,327 critically ill patients hospitalized with low-output heart failure in need of inotropic therapy.

INTERVENTION

Levosimendan versus dobutamine.

MEASUREMENTS

All-cause mortality at 31 and 180 days in patients who survived initial hospitalization with/without β-blocker use at entry and/or at discharge.

RESULTS

Patients on β-blockers at entry and at discharge had significantly lower 31-day (p < .0001) and 180-day (p < .0001) mortality compared to patients without β-blockers use at both time points. The association was robust when adjusted for age and co-morbidities (p = .006 at 31 days; p = .003 at 180 days).

CONCLUSIONS

Those results strongly suggest, in severe acutely decompensated heart failure patients, admitted on β-blockers, to continue on them at discharge.

Differences in the magnitude of wave reflection account for differential effects of amlodipine- versus atenolol-based regimens on central blood pressure: an Anglo-Scandinavian Cardiac Outcome Trial substudy

Antihypertensive agents may differ in their effects on central systolic blood pressure, and this may contribute to treatment-related differences in cardiovascular outcomes. In a substudy of the Anglo-Scandinavian Cardiac Outcome Trial, we investigated whether directly measured carotid systolic blood pressure differed between people randomized to amlodipine- and atenolol-based therapies and whether this is accounted for by differences in wave reflection patterns. Additional analysis was undertaken to establish whether differences in carotid systolic blood pressure predicted left ventricular mass, accounting for between-treatment differences in left ventricular mass index. Blood pressure and flow velocity were measured in the right carotid artery of 259 patients. Wave intensity analysis was used to separate and quantify forward and backward waves. Brachial blood pressure did not differ significantly between groups, but carotid systolic blood pressure (127 [12] versus 133 [15] mm Hg; P<0.001), the ratio of backward:forward pressure (0.48 [0.17] versus 0.53 [0.19]; P=0.01), and wave reflection index (19.8% [10.9%] versus 23.3% [13.3%]; P=0.02) were significantly lower in patients randomized to amlodipine-based therapy. Left ventricular mass index was also lower in this group, and adjustment for carotid blood pressure attenuated treatment differences to a greater extent than brachial blood pressure. Carotid systolic blood pressure was also a significant independent predictor of left ventricular mass index in a multivariate model. Carotid systolic blood pressure is lower in people randomized to amlodipine-based compared with atenolol-based treatment despite there being no significant difference in brachial blood pressure. This difference is attributable to a lesser magnitude of wave reflection in patients randomized to the amlodipine-based regimen.

Analysis of randomized controlled trials on the effect of magnitude of heart rate reduction on clinical outcomes in patients with systolic chronic heart failure receiving beta-blockers

Beta blockers improve cardiac function and prolong survival in patients with systolic chronic heart failure (CHF). However, the exact mechanisms underlying these benefits are uncertain. Specifically, it is unclear whether a close relation exists between heart rate (HR) reduction and clinical outcomes with these agents. This hypothesis was therefore tested within randomized controlled trials of beta blockers in systolic CHF. Left ventricular ejection fraction (LVEF) and HR values at baseline and study end were obtained from available beta-blocker randomized clinical trials. The relation between change in HR and all-cause mortality as well as the LVEF was determined using regression analysis. Thirty-five trials, which included 22,926 patients with a mean follow-up duration of 9.6 months, were analyzed for all-cause mortality, the LVEF, and HR. There was a close relation between all-cause annualized mortality rate and HR (adjusted R2 = 0.51, p = 0.004). A strong correlation between change in HR and change in LVEF (adjusted R2 = 0.48, p = 0.000) was also observed. When only trials with >100 patients were included, an even tighter correlation was seen (adjusted R2 = 0.60, p = 0.0004). In conclusion, these analyses indicate that a major contributor to the clinical benefits of beta-blocker therapy in systolic CHF may be the HR-lowering effect of these agents. Therefore, the magnitude of HR reduction may be more important than the achievement of target dose in beta-blocker treatment of systolic CHF.

Should beta-blocker therapy be reduced or withdrawn after an episode of decompensated heart failure? Results from COMET

BACKGROUND

It is unclear whether beta-blocker therapy should be reduced or withdrawn in patients who develop acute decompensated heart failure (HF). We studied the relationship between changes in beta-blocker dose and outcome in patients surviving a HF hospitalisation in COMET.

METHODS

Patients hospitalised for HF were subdivided on the basis of the beta-blocker dose administered at the visit following hospitalisation, compared to that administered before.

RESULTS

In COMET, 752/3029 patients (25%, 361 carvedilol and 391 metoprolol) had a non-fatal HF hospitalisation while on study treatment. Of these, 61 patients (8%) had beta-blocker treatment withdrawn, 162 (22%) had a dose reduction and 529 (70%) were maintained on the same dose. One-and two-year cumulative mortality rates were 28.7% and 44.6% for patients withdrawn from study medication, 37.4% and 51.4% for those with a reduced dosage (n.s.) and 19.1% and 32.5% for those maintained on the same dose (HR,1.59; 95%CI, 1.28-1.98; p<0.001, compared to the others). The result remained significant in a multivariable model: (HR, 1.30; 95%CI, 1.02-1.66; p=0.0318). No interaction with the beneficial effects of carvedilol, compared to metoprolol, on outcome was observed (p=0.8436).

CONCLUSIONS

HF hospitalisations are associated with a high subsequent mortality. The risk of death is higher in patients who discontinue beta-blocker therapy or have their dose reduced. The increase in mortality is only partially explained by the worse prognostic profile of these patients.

β-blocker therapy of heart failure: an update

The beneficial effects of beta-blocker therapy in patients with heart failure have been consistently shown by multi-center randomised trials. These agents are effective and also relatively well tolerated in the elderly and in patients with diabetes and advanced heart failure--traditionally considered as relative contraindications to their administration. However, the use of beta-blockers in clinical practice remains low. The difficulties in their initiation and up-titration may be overcome by patient and physician education, as well as by their initiation during hospitalisation and/or the involvement of non-physician providers (i.e., a nurse facilitator). Forthcoming advances in the pharmacokinetic and pharmacodynamic characteristics of some beta-blockers, and testing of novel methods for patient and drug selection may be based on genetic testing, and may allow further improvement of beta-blocker therapy in the next future.

Beta-blockers in heart failure: are pharmacological differences clinically important?

Beta-blockers are not an homogeneous group of agents. Only three beta-blockers, carvedilol, bisoprolol and metoprolol succinate, have had favorable effects on prognosis in controlled clinical trials in the patients with chronic heart failure. However, pharmacological differences exist between them. Metoprolol and bisoprolol are selective for beta(1)-adrenergic receptors while carvedilol blocks also beta(2)-, and alpha(1)- adrenergic receptors, and has associated antioxidant, anti-endothelin and antiproliferative properties. In COMET carvedilol was associated with a significant reduction in mortality compared to metoprolol tartrate further showing that different beta-blockers may have different effects on the outcome. These differences may be related to the ancillary properties of carvedilol or to its broader antiadrenergic profile. However, also more effective and prolonged blockade of beta1 adrenergic receptors may occur with carvedilol compared to metoprolol.

Multiple cardiovascular considerations in a 76-year-old man

A 76-year-old man with a history of myocardial infarction, Type 2 diabetes, hypertension, hypercholesterolemia, and heart failure presents with muscle pain and spasm. A number of medication-related problems are identified by the pharmacist. Prioritization of medication-related problems and therapeutic recommendations are provided. The medication-related problems described in this case reinforce the need for establishing individualized action plans and avoiding making too many changes in medication regimens at one time. In addition, the issue of nonpharmacological causes of symptoms can be overlooked when focusing on medication-induced illness.

Do metoprolol and carvedilol have equivalent effects on diurnal heart rate in patients with chronic heart failure?

BACKGROUND

Carvedilol exerted a greater reduction in mortality than metoprolol tartrate in the Carvedilol or Metoprolol European Trial (COMET). However, it is unclear if the degree and time course of beta1-blockade during a 24-h period was similar with each agent at the doses used. Therefore we analyzed 24-h ECG Holter recordings from a study which compared the long-term clinical efficacy of metoprolol tartrate to carvedilol in chronic heart failure patients using the same dosing regimen as in COMET.

METHODS AND RESULTS

Fifty-one patients with chronic heart failure with a mean LVEF 26+/-1.8% were randomized in a double-blind fashion to receive metoprolol tartrate 50 mg bid or carvedilol 25 mg bid. 24-h ECG monitoring (Holter) was performed at baseline, 12 weeks and 1 year. Adequate quality recordings for analysis were obtained from 43 subjects at baseline, 42 at 12 weeks and 29 subjects at 1 year. Both drugs produced a fall in average 24-h heart rate from baseline at 12 weeks and at 1 year: metoprolol 88+/-3 to 71+/-2 and 69+/-3 bpm; carvedilol 83+/-3 to 70+/-2 and 70+/-3 bpm respectively (all p<0.001). The pattern of suppression of heart rate during the 24-h period was similar for both drugs.

CONCLUSION

Metoprolol tartrate 50 mg bid and carvedilol 25 mg bid had similar effects on 24-h heart rate. This result suggests that the degree of beta1-blockade produced by these two drugs in these doses is comparable and the superior survival effect of carvedilol compared to metoprolol seen in COMET is likely to be due to actions of carvedilol other than beta1-blockade.

Effects of Different Degrees of Sympathetic Antagonism on Cytokine Network in Patients With Ischemic Dilated Cardiomyopathy

BACKGROUND

The proinflammatory cytokines have been implicated in the pathogenesis of heart failure. Recent studies have shown that beta-adrenergic blockade can modulate cytokine production. This study investigates the different impact of different degrees of sympathetic antagonism on circulating levels of cytokines in patients with heart failure resulting from ischemic dilated cardiomyopathy (IDC).

METHODS AND RESULTS

Thirty-five patients with IDC were randomly assigned to receive metoprolol or carvedilol in an open-label study. Echocardiographic measurements and circulating levels of tumor necrosis (TNF)-alpha and interleukin (IL)-1beta and IL-6 were obtained at baseline and after 3 months of treatment. The 2 beta-blockers significantly improved the left ventricular ejection fraction and reduced end-diastolic and end-systolic volume. The magnitude of these changes was greater with carvedilol than with metoprolol (respectively P < .001, P < .05, and P < .05). Both treatments induced a significant decrease in the levels of cytokines (for all P < .01), but the decrease in TNF-alpha and IL-1beta was more consistent in the carvedilol group ( P < .01).

CONCLUSION

Our results support the hypothesis that a more complete block of sympathetic activity by carvedilol induces a greater decrease in the circulating levels of proinflammatory cytokines that could explain, at least in part, the better improvement in the left ventricular remodelling and systolic function in patients with IDC.

Use of Beta-Blockers in Older Adults with Chronic Heart Failure

Most heart failure patients are older adults. Angiotensin-converting enzyme (ACE) inhibitors reduce mortality and morbidity in patients with systolic heart failure. However, the annual mortality rate in patients with systolic heart failure receiving ACE inhibitors is about 12%. Beta-blockers further reduce mortality rate by an additional 35% to 65%. Because of potential adverse effects, the rate of beta-blocker use is likely to be low in older adults with systolic heart failure. In this article, we review the findings of the major beta-blocker trials in systolic heart failure and discuss the potential benefits and adverse effects of beta-blockers, along with various practical aspects of their use in older adults with systolic heart failure. Subgroup analyses of these trials suggest that the survival benefits of beta-blockers observed in the main trials are also observed in persons 65 years of age and older. However, data are limited for heart failure patients 85 years of age and older. About half of the older adults with heart failure do not have systolic heart failure, and currently there is no evidence that beta-blockers also improve survival in these patients. Beta-blockers might play a beneficial role in heart failure patients without systolic heart failure by reducing high blood pressure, high heart rate, or myocardial ischemia, conditions known to impair ventricular relaxation. Adequate knowledge of the commonly used beta-blockers, along with careful patient selection and close monitoring for adverse effects will allow safe initiation and continuation of beta-blocker use for older adults with systolic heart failure. It is likely that lower doses of beta-blockers are as effective as higher doses.

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.

Beta-blockers in heart failure: Is more better?

Therapies that modulate the sympathetic nervous system and renin-angiotensin-aldosterone system reduce morbidity and mortality in patients with heart failure. However, they are grossly underused in clinical practice; when used, the doses prescribed are substantially smaller than the target doses used in the large-scale studies that established their utility. Whether these suboptimal doses are as effective in reducing morbidity and mortality is largely unknown. This review focuses on the relationship between the dose of b-blockers and their effect on clinical outcomes. Because direct dose comparisons of b-blockers are limited, we draw upon a broader spectrum of clinical trials across the cardiovascular continuum that involved neurohormonal modulators to address the question, "Is more better?"

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.

Pharmacokinetic considerations of formulation: extended-release metoprolol succinate in the treatment of heart failure

Extended-release (ER) metoprolol succinate is a controlled-release formulation designed to deliver metoprolol succinate at a near constant rate for approximately 20 h, independent of food intake and gastrointestinal pH. Once-daily dosing of ER metoprolol succinate 12.5-200 mg produces even plasma concentrations over a 24-h period, without the marked peaks and troughs characteristically observed with the immediate-release (IR) formulation. This leads to consistent beta1-blockade over 24 h, while maintaining cardioselectivity at doses up to 200 mg daily. Pharmacokinetic studies have also been performed in heart failure patients and have demonstrated that ER metoprolol succinate is associated with a more pronounced and even beta1-blockade over a 24-h period than the IR formulation. The efficacy and good tolerability of ER metoprolol succinate in heart failure patients has now been demonstrated in a large-scale clinical trial.

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.

Beta-blocker therapy influences the hemodynamic response to inotropic agents in patients with heart failure: a randomized comparison of dobutamine and enoximone before and after chronic treatment with metoprolol or carvedilol

OBJECTIVE

We compared the hemodynamic effects of dobutamine and enoximone administration before and after long-term beta-blocker therapy with metoprolol or carvedilol in patients with chronic heart failure (HF).

BACKGROUND

Patients with HF on beta-blocker therapy may need hemodynamic support with inotropic agents, and the hemodynamic response may be influenced by both the inotropic agent and the beta-blocker used.

METHODS

The hemodynamic effects of dobutamine (5 to 20 microg/kg/min intravenously) and enoximone (0.5 to 2 mg/kg intravenously) were assessed by pulmonary artery catheterization in 29 patients with chronic HF before and after 9 to 12 months of treatment with metoprolol or carvedilol at standard target maintenance oral doses. Hemodynamic studies were performed after >/=12 h of wash-out from all cardiovascular medications, except the beta-blockers that were administered 3 h before the second study.

RESULTS

Compared with before beta-blocker therapy, metoprolol treatment decreased the magnitude of mean pulmonary artery pressure (PAP) and pulmonary wedge pressure (PWP) decline during dobutamine infusion and increased the cardiac index (CI) and stroke volume index (SVI) response to enoximone administration, without any effect on other hemodynamic parameters. Carvedilol treatment abolished the increase in heart rate, SVI, and CI and caused a rise, rather than a decline, in PAP, PWP, systemic vascular resistance, and pulmonary vascular resistance during dobutamine infusion. The hemodynamic response to enoximone, however, was maintained or enhanced in the presence of carvedilol.

CONCLUSIONS

In contrast with its effects on enoximone, carvedilol and, to a lesser extent, metoprolol treatment may significantly inhibit the favorable hemodynamic response to dobutamine. No such beta-blocker-related attenuation of hemodynamic effects occurs with enoximone.

Modulation of beta-adrenergic receptor subtype activities in perioperative medicine: mechanisms and sites of action

This review focuses on the mechanisms and sites of action underlying beta-adrenergic antagonism in perioperative medicine. A large body of knowledge has recently emerged from basic and clinical research concerning the mechanisms of the life-saving effects of beta-adrenergic antagonists (beta-AAs) in high-risk cardiac patients. This article re-emphasizes the mechanisms underlying beta-adrenergic antagonism and also illuminates novel rationales behind the use of perioperative beta-AAs from a biological point of view. Particularly, it delineates new concepts of beta-adrenergic signal transduction emerging from transgenic animal models. The role of the different characteristics of various beta-AAs is discussed, and evidence will be presented for the selection of one specific agent over another on the basis of individual drug profiles in defined clinical situations. The salutary effects of beta-AAs on the cardiovascular system will be described at the cellular and molecular levels. Beta-AAs exhibit many effects beyond a reduction in heart rate, which are less known by perioperative physicians but equally desirable in the perioperative care of high-risk cardiac patients. These include effects on core components of an anaesthetic regimen, such as analgesia, hypnosis, and memory function. Despite overwhelming evidence of benefit, beta-AAs are currently under-utilized in the perioperative period because of concerns of potential adverse effects and toxicity. The effects of acute administration of beta-AAs on cardiac function in the compromised patient and strategies to counteract potential adverse effects will be discussed in detail. This may help to overcome barriers to the initiation of perioperative treatment with beta-AAs in a larger number of high-risk cardiac patients undergoing surgery.

Dose-related effects of metoprolol on heart rate and pharmacokinetics in heart failure

BACKGROUND

The pharmacokinetics and pharmacodynamics of immediate-release (IR) metoprolol, 50 mg 3 times daily, were compared with those of different doses of controlled-release/extended-release metoprolol (CR/XL) given once daily.

METHODS AND RESULTS

Fifteen patients with chronic heart failure were randomized to a 3-way crossover study to receive metoprolol IR 50 mg 3 times daily, CR/XL 100 mg once daily, and CR/XL 200 mg once daily for 7 days. On the seventh day of each treatment, serial plasma samples were drawn and standardized exercise tests and a 24-hour Holter recording were performed. Metoprolol IR 50 mg produced peak plasma levels comparable to those observed for CR/XL 200 mg (285 v 263 nmol/L). The difference in mean 24-hour heart rate between CR/XL 100 mg and IR 50 mg was 1.0 bpm (95% confidence interval [CI]), -2.9 to 4.9; NS) compared with -3.8 bpm (95% CI, -7.6 to -0.04; P = .048) between CR/XL 200 mg and IR 50 mg. Submaximal exercise heart rate was lower for patients receiving CR/XL 200 mg than those receiving IR 50 mg. No difference in tolerance or exercise performance was observed between treatment regimens.

CONCLUSIONS

Peak plasma levels produced by metoprolol 200 mg CR/XL were similar to those of 50 mg IR. Metoprolol CR/XL 200 mg was associated with a more pronounced suppression of heart rate than metoprolol IR 50 mg. It is suggested that patients can safely be switched from multiple dosing of metoprolol IR 50 mg to a once-daily dose of metoprolol CR/XL.

Metoprolol: a review of its use in chronic heart failure

Metoprolol, a relatively selective beta1-blocker, is devoid of intrinsic sympathomimetic activity and possesses weak membrane stabilising activity. The drug has an established role in the management of essential hypertension and angina pectoris, and more recently, in patients with chronic heart failure. The effects of metoprolol controlled-release/extended-release (CR/XL) in patients with stable, predominantly mild to moderate (NYHA functional class II to III) chronic heart failure have been evaluated in the large Metoprolol CR/XL Randomised Intervention Trial in Congestive Heart Failure (MERIT-HF) trial and the much smaller Randomized Evaluation of Strategies for Left Ventricular Dysfunction (RESOLVD) pilot study. Treatment with metoprolol CR/XL was initiated at a low dosage of 12.5 to 25 mg once daily and gradually increased at 2-weekly intervals until the target dosage (200 mg once daily) or maximal tolerated dosage had been attained in patients receiving standard therapy for heart failure. At 12 months, metoprolol CR/XL was associated with a 34% reduction in relative risk of all-cause mortality in patients with chronic heart failure due to ischaemic or dilated cardiomyopathy in the MERIT-HF trial. The incidence of sudden death and death due to progressive heart failure were both significantly decreased with metoprolol CR/XL. Similarly, a trend towards decreased mortality in the metoprolol CR/XL group compared with placebo was observed in the RESOLVD trial. Data from small numbers of patients with severe (NYHA functional class IV) heart failure indicate that metoprolol CR/XL is effective in this subset of patients. However, no firm conclusions can yet be drawn. Improvement from baseline values in NYHA functional class, exercise capacity and some measures of quality of life with metoprolol CR/XL or immediate-release metoprolol were significantly greater than those with placebo. The drug is well tolerated when treatment is initiated in low dosages and gradually increased at intervals of 1 to 2 weeks.

CONCLUSIONS

Metoprolol CR/XL effectively decreases mortality and improves clinical status in patients with stable mild to moderate (NYHA functional class II or III) chronic heart failure due to left ventricular systolic dysfunction, and the drug is effective in patients with ischaemic or dilated cardiomyopathy. Although limited data indicate that metoprolol CR/XL is effective in patients with severe (NYHA functional class IV) chronic heart failure, more data are needed to confirm these findings. Treatment with metoprolol CR/XL significantly reduced the incidence of sudden death and death due to progressive heart failure.

Differential effects of beta-blockers in patients with heart failure: A prospective, randomized, double-blind comparison of the long-term effects of metoprolol versus carvedilol

BACKGROUND

Both metoprolol and carvedilol produce hemodynamic and clinical benefits in patients with chronic heart failure; carvedilol exerts greater antiadrenergic effects than metoprolol, but it is unknown whether this pharmacological difference results in hemodynamic and clinical differences between the 2 drugs.

METHODS AND RESULTS

We randomized 150 patients with heart failure (left ventricular ejection fraction </=0.35) to double-blind treatment with either metoprolol or carvedilol. When compared with metoprolol (124+/-55 mg/d), patients treated with carvedilol (49+/-18 mg/d) showed larger increases in left ventricular ejection fraction at rest (+10.9+/-11.0 versus +7.2+/-7.7 U, P=0.038) and in left ventricular stroke volume and stroke work during exercise (both P<0. 05) after 13 to 15 months of treatment. In addition, carvedilol produced greater decreases in mean pulmonary artery pressure and pulmonary wedge pressure, both at rest and during exercise, than metoprolol (all P<0.05). In contrast, the metoprolol group showed greater increases in maximal exercise capacity than the carvedilol group (P=0.035), but the 2 drugs improved symptoms, submaximal exercise tolerance, and quality of life to a similar degree. After a mean of 23+/-11 months of follow-up, 21 patients in the metoprolol group and 17 patients in the carvedilol group died or underwent urgent transplantation.

CONCLUSIONS

The present study demonstrates that during long-term therapy, carvedilol improves cardiac performance to a greater extent than metoprolol when administered to patients with heart failure in the doses shown to be effective in clinical trials. These differences were likely related to a greater antiadrenergic activity of carvedilol.