Prospective crossover comparison of carvedilol and metoprolol in patients with chronic heart failure

Metabolomics of repetitive myocardial stunning in chronic multivessel coronary artery stenosis: Effect of non-selective and selective β1-receptor blockers

Chronic coronary artery stenosis can lead to regional myocardial dysfunction in the absence of myocardial infarction by repetitive stunning, hibernation or both. The molecular mechanisms underlying repetitive stunning-associated myocardial dysfunction are not clear. We used non-targeted metabolomics to elucidate responses to chronically stunned myocardium in a canine model with and without β-adrenergic blockade treatment. After development of left ventricular systolic dysfunction induced by ameroid constrictors on the coronary arteries, animals were randomized to 3 months of placebo, metoprolol or carvedilol. We compared these two β-blockers with their different β-adrenergic selectivities on myocardial function, perfusion and metabolic pathways involved in tissue undergoing chronic stunning. Control animals underwent sham surgery. Dysfunction in stunned myocardium was associated with reduced fatty acid oxidation and enhanced ketogenic amino acid metabolism, together with alterations in mitochondrial membrane phospholipid composition. These changes were consistent with impaired mitochondrial function and were linked to reduced nitric oxide and peroxisome proliferator-activated receptor signalling, resulting in a decline in adenosine monophosphate-activated protein kinase. Mitochondrial changes were ameliorated by carvedilol more than metoprolol, and improvement was linked to nitric oxide and possibly hydrogen sulphide signalling. In summary, repetitive myocardial stunning commonly seen in chronic multivessel coronary artery disease is associated with adverse metabolic remodelling linked to mitochondrial dysfunction and specific signalling pathways. These changes are reversed by β-blockers, with the non-selective inhibitor having a more favourable impact. This is the first investigation to demonstrate that β-blockade-associated improvement of ventricular function in chronic myocardial stunning is associated with restoration of mitochondrial function. KEY POINTS: The mechanisms responsible for the metabolic changes associated with repetitive myocardial stunning seen in chronic multivessel coronary artery disease have not been fully investigated. In a canine model of repetitive myocardial stunning, we showed that carvedilol, a non-selective β-receptor blocker, ameliorated adverse metabolic remodelling compared to metoprolol, a selective β1-receptor blocker, by improving nitric oxide synthase and adenosine monophosphate protein kinase function, enhancing calcium/calmodulin-dependent protein kinase, probably increasing hydrogen sulphide, and suppressing cyclic-adenosine monophosphate signalling. Mitochondrial fatty acid oxidation alterations were ameliorated by carvedilol to a larger extent than metoprolol; this improvement was linked to nitric oxide and possibly hydrogen sulphide signalling. Both β-blockers improved the cardiac energy imbalance by reducing metabolites in ketogenic amino acid and nucleotide metabolism. These results elucidated why metabolic remodelling with carvedilol is preferable to metoprolol when treating chronic ischaemic left ventricular systolic dysfunction caused by repetitive myocardial stunning.

Recent Advances in β2-Agonists for Treatment of Chronic Respiratory Diseases and Heart Failure

β₂-Adrenoceptor (β₂-AR) agonists are widely used as bronchodilators. The emerge of ultralong acting β₂-agonists is an important breakthrough in pulmonary medicine. In this review, we will provide mechanistic insights into the application of β₂-agonists in asthma, chronic obstructive pulmonary disease (COPD), and heart failure (HF). Recent studies in β-AR signal transduction have revealed opposing functions of the β₁-AR and the β₂-AR on cardiomyocyte survival. Thus, β₂-agonists and β-blockers in combination may represent a novel strategy for HF management. Allosteric modulation and biased agonism at the β₂-AR also provide a theoretical basis for developing drugs with novel mechanisms of action and pharmacological profiles. Overlap of COPD and HF presents a substantial clinical challenge but also a unique opportunity for evaluation of the cardiovascular safety of β₂-agonists. Further basic and clinical research along these lines can help us develop better drugs and innovative strategies for the management of these difficult-to-treat diseases.

Improving performance of an accountable care organization on a quality measure assessing β-blocker use in systolic heart failure

PURPOSE

The implementation and outcomes are described for a clinical pharmacist-generated initiative to improve the performance of a Medicare Pioneer accountable care organization (ACO) quality measure evaluating the percentage of patients at least 18 years of age with heart failure and a left ventricular ejection fraction (LVEF) of less than 40% who are prescribed with an evidence-based β-blocker (carvedilol, metoprolol succinate, or bisoprolol).

SUMMARY

Atrius Health clinical pharmacists developed several educational documents to facilitate appropriate prescribing of evidence-based therapies in patients with heart failure. After educating clinicians, clinical pharmacists reviewed patient charts to determine eligibility for initiating or switching to evidence-based β-blocker therapy. Medicare Pioneer ACO patients 18-85 years of age with heart failure and a current or prior LVEF of less than 40% were reviewed. Patients had a current prescription for metoprolol tartrate, atenolol, or no β-blocker. Patients were considered ineligible if they had a documented contraindication or intolerance to β-blocker therapy or were clinically unstable. Recommendations to initiate or switch to an appropriate β-blocker were sent electronically by a clinical pharmacist to an eligible patient's treating physician before a scheduled office visit. In approximately three months, 48 patients underwent chart review by a clinical pharmacist. Performance improved by 8% after the implementation, with 82% of eligible patients achieving the quality measure in 2014-an increase from 74% in 2013.

CONCLUSION

The performance on a Medicare Pioneer ACO quality measure evaluating β-blocker use in systolic heart failure improved in a one-year period after a clinical pharmacist-generated initiative was implemented at Atrius Health practice sites.

Anti-inflammatory and pro-angiogenic effects of beta blockers in a canine model of chronic ischemic cardiomyopathy: comparison between carvedilol and metoprolol

There is controversy regarding the superiority of carvedilol (C) over metoprolol (M) in congestive heart failure. We hypothesized that C is superior to M in chronic ischemic cardiomyopathy because of its better anti-inflammatory and pro-angiogenic effects. In order to test our hypothesis we used a chronic canine model of multivessel ischemic cardiomyopathy where myocardial microcatheters were placed from which interstitial fluid was collected over time to measure leukocyte count and cytokine levels. After development of left ventricular dysfunction, the animals were randomized into four groups: sham (n = 7), placebo (n = 8), M (n = 11), and C (n = 10), and followed for 3 months after treatment initiation. Tissue was examined for immunohistochemistry, oxidative stress, and capillary density. At 3 months both rest and stress wall thickening were better in C compared to the other groups. At the end of 3 months of treatment end-systolic wall stress also decreased the most in C. Similarly resting myocardial blood flow (MBF) improved the most in C as did the stress endocardial/epicardial MBF. Myocardial interstitial fluid showed greater attenuation of leukocytosis with C compared to M, which was associated with less fibrosis and oxidative stress. C also had higher IL-10 level and capillary density. In conclusion, in a chronic canine model of multivessel ischemic cardiomyopathy we found 3 months of C treatment resulted in better resting global and regional function as well as better regional function at stress compared to M. These changes were associated with higher myocardial levels of the anti-inflammatory cytokine IL-10 and less myocardial oxidative stress, leukocytosis, and fibrosis. Capillary density and MBF were almost normalized. Thus in the doses used in this study, C appears to be superior to M in a chronic canine model of ischemic cardiomyopathy from beneficial effects on inflammation and angiogenesis. Further studies are required for comparing additional doses of these drugs.

Association between resting heart rate, chronotropic index, and long-term outcomes in patients with heart failure receiving β-blocker therapy: data from the HF-ACTION trial

AIMS

The aim of this study was to assess the association between resting heart rate (HR), chronotropic index (CI), and clinical outcomes in optimally treated chronic heart failure (HF) patients on β-blocker therapy.

METHODS AND RESULTS

We performed a sub-study in 1118 patients with HF and reduced ejection fraction (EF < 35%) included in the HF-ACTION trial. Patients in sinus rhythm who received a β-blocker and who performed with maximal effort on the exercise test were included. Chronotropic index was calculated as an index of HR reserve achieved, by using the equation (220-age) for estimating maximum HR. A sensitivity analysis using an equation developed for HF patients on β-blockers was also performed. Cox proportional hazards models were fit to assess the association between CI and clinical outcomes. Median (25th, 75th percentiles) follow-up was 32 (21, 44) months. In a multivariable model including resting HR and CI as continuous variables, neither was associated with the primary outcome of all-cause mortality or hospitalization. However, each 0.1 unit decrease in CI <0.6 was associated with 17% increased risk of all-cause mortality (hazard ratio 1.17, 95% confidence interval 1.01-1.36; P = 0.036), and 13% increased risk of cardiovascular mortality or HF hospitalization (hazard ratio 1.13, 1.02-1.26; P = 0.025). Overall, 666 of 1118 (60%) patients had a CI <0.6. Chronotropic index did not retain statistical significance when dichotomized at a value of ≤ 0.62.

CONCLUSION

In HF patients receiving optimal medical therapy, a decrease in CI <0.6 was associated with adverse clinical outcomes. Obtaining an optimal HR response to exercise, even in patients receiving optimal β-blocker therapy, may be a therapeutic target in the HF population.

Predicting maximal HR in heart failure patients on β-blockade therapy

PURPOSE

Standards for estimating maximal HR are important when interpreting the adequacy of physiologic stress during exercise testing, assessing chronotropic response, and prescribing an exercise training regimen. The equation 220 - age is used to estimate maximum HR; however, it overestimates measured maximal HR in patients taking β-adrenergic blockade (βB) therapy. This study developed and validated a practical equation to predict maximal HR in patients with heart failure (HF) taking βB therapy.

METHODS

Data from symptom-limited exercise tests completed on patients with systolic HF participating in the Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training trial and taking a βB agent were used to develop a simplified equation, which was validated using bootstrapping.

RESULTS

The simplified derived equation was 119 + 0.5 (resting HR) - 0.5 (age) - (0, if test was completed using a treadmill; 5, if using a stationary bike). The R2 and SEE were 0.28 and 18 beats·min(-1), respectively. Validation of this equation yielded a mean R and SEE of 0.28 and 18 beats·min(-1), respectively. For the equation 220 - age, the R2 was -2.93, and the SEE was 43 beats·min(-1).

CONCLUSIONS

We report a valid and simple population-specific equation for estimating peak HR in patients with HF taking βB therapy. This equation should be helpful when evaluating chronotropic response or assessing if a maximum effort was provided during exercise testing. We caution, however, that the magnitude of the variation (SEE = 18 beats·min(-1)) associated with this prediction equation may make it impractical when prescribing exercise intensity.

Differences between bisoprolol and carvedilol in patients with chronic heart failure and chronic obstructive pulmonary disease: a randomized trial

BACKGROUND

Chronic obstructive pulmonary disease (COPD) frequently coexists in patients with chronic heart failure (CHF) and is a key factor for beta blocker underprescription and underdosing. This study compared effects of bisoprolol and carvedilol in patients with both conditions.

METHODS

This was a randomized open-label study, of bisoprolol and carvedilol during initiation and uptitration to target or maximal tolerated dose. Pulmonary function testing, 12-lead electrocardiogram, and N-terminal pro brain natriuretic peptide were measured at baseline and follow-up.

RESULTS

We randomized 63 elderly patients (73 ± 9 years, 81% men, left ventricular ejection fraction 33 ± 7%) with mild to moderate CHF (54% New York Heart Assocation class II) and moderate to severe COPD (76% Global initiative for chronic Obstructive Lung Disease stage 2). Target dose was tolerated by 31 (49%) patients and 19 (30%) patients experienced adverse events during follow-up (19% bisoprolol, 42% carvedilol, p = 0.045). Study medication had to be withdrawn in 8 (13%) patients (bisoprolol: 2 due to hypotension, 1 due to bradycardia; carvedilol: 2 due to hypotension and 1 due to wheezing, dyspnoea, and oedema, respectively). Forced expiratory volume in 1(st) second significantly increased in bisoprolol (1561 ± 414 ml to 1698 ± 519 ml, p = 0.046) but not carvedilol (1704 ± 484 to 1734 ± 548, p = 0.44) group. Both agents reduced heart rate (bisoprolol: 75 ± 14 to 68 ± 10, p = 0.007; carvedilol 78 ± 14 to 72 ± 12, p = 0.016) and had no effect on N-terminal pro brain natriuretic peptide.

CONCLUSIONS

Beta blockers frequently caused adverse events, and thus 49% of patients could tolerate the target dose. Bisoprolol induced demonstrable improvement in pulmonary function and caused less adverse events.

Differences between beta-blockers in patients with chronic heart failure and chronic obstructive pulmonary disease: a randomized crossover trial

OBJECTIVES

The purpose of this study was to determine the respiratory, hemodynamic, and clinical effects of switching between beta1-selective and nonselective beta-blockers in patients with chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD).

BACKGROUND

Carvedilol, metoprolol succinate, and bisoprolol are established beta-blockers for treating CHF. Whether differences in beta-receptor specificities affect lung or vascular function in CHF patients, particularly those with coexistent COPD, remains incompletely characterized.

METHODS

A randomized, open label, triple-crossover trial involving 51 subjects receiving optimal therapy for CHF was conducted in 2 Australian teaching hospitals. Subjects received each beta-blocker, dose-matched, for 6 weeks before resuming their original beta-blocker. Echocardiography, N-terminal pro-hormone brain natriuretic peptide, central augmented pressure from pulse waveform analysis, respiratory function testing, 6-min walk distance, and New York Heart Association (NYHA) functional class were assessed at each visit.

RESULTS

Of 51 subjects with a mean age of 66 +/- 12 years, NYHA functional class I (n = 6), II (n = 29), or III (n = 16), and left ventricular ejection fraction mean of 37 +/- 10%, 35 had coexistent COPD. N-terminal pro-hormone brain natriuretic peptide was significantly lower with carvedilol than with metoprolol or bisoprolol (mean: carvedilol 1,001 [95% confidence interval (CI): 633 to 1,367] ng/l; metoprolol 1,371 [95% CI: 778 to 1,964] ng/l; bisoprolol 1,349 [95% CI: 782 to 1,916] ng/l; p < 0.01), and returned to baseline level on resumption of the initial beta-blocker. Central augmented pressure, a measure of pulsatile afterload, was lowest with carvedilol (carvedilol 9.9 [95% CI: 7.7 to 12.2] mm Hg; metoprolol 11.5 [95% CI: 9.3 to 13.8] mm Hg; bisoprolol 12.2 [95% CI: 9.6 to 14.7] mm Hg; p < 0.05). In subjects with COPD, forced expiratory volume in 1 s was lowest with carvedilol and highest with bisoprolol (carvedilol 1.85 [95% CI: 1.67 to 2.03] l/s; metoprolol 1.94 [95% CI: 1.73 to 2.14] l/s; bisoprolol 2.0 [95% CI: 1.79 to 2.22] l/s; p < 0.001). The NYHA functional class, 6-min walk distance, and left ventricular ejection fraction did not change. The beta-blocker switches were well tolerated.

CONCLUSIONS

Switching between beta1-selective beta-blockers and the nonselective beta-blocker carvedilol is well tolerated but results in demonstrable changes in airway function, most marked in patients with COPD. Switching from beta1-selective beta-blockers to carvedilol causes short-term reduction of central augmented pressure and N-terminal pro-hormone brain natriuretic peptide. (Comparison of Nonselective and Beta1-Selective Beta-Blockers on Respiratory and Arterial Function and Cardiac Chamber Dynamics in Patients With Chronic Stable Congestive Cardiac Failure; Australian New Zealand Clinical Trials Registry, ACTRN12605000504617).

Beta-Blocker Treatment of Chronic Heart Failure: Comparison of Carvedilol and Metoprolol

Beta blockers have been shown to prolong survival in chronic heart failure. It is currently a matter of debate whether any beta blocker is superior to the other in terms of improving symptoms, left ventricular function, or prognosis. A number of comparative studies have been performed with metoprolol, a beta1-selective second-generation beta blocker, and carvedilol, a nonselective and vasodilatative third-generation beta blocker. This review will focus on the different pharmacological profiles of carvedilol and metoprolol as well as on the clinical consequences derived from these differences. The results indicate that in some studies carvedilol is superior to metoprolol in improving left ventricular ejection fraction. However, because there is no conclusive evidence that carvedilol is superior to metoprolol in terms of prognosis, it is not justified to substitute metoprolol with carvedilol. Comparative data on mortality reduction are not available before termination of the Carvedilol or Metoprolol European Trial. Nevertheless, the different effects of both beta blockers on the beta-adrenergic system have an impact on tolerability and beta-adrenergic responsiveness and thus exercise tolerance in heart-failure patients.

Hemodynamic responses and long-term follow-up results in patients using chronic beta 1-selective and nonselective beta-blockers during dobutamine stress echocardiography

OBJECTIVE

This study was undertaken to determine to what extent hemodynamic responses to dobutamine infusion between patients using concomitant beta1-selective or nonselective beta-blockers differ and whether this difference affects the long-term prognostic value of dobutamine stress echocardiography with respect to cardiac events.

DESIGN

Single center, observational study.

METHODS

A total of 1234 patients using chronic beta-blockers underwent dobutamine stress echocardiography and were prospectively included in the study. Heart rate and blood pressure responses were measured during the dobutamine stress echocardiography protocol. During a median follow-up time of 4 years (range: 0.5-14 years), overall and cardiac mortality and nonfatal myocardial infarction were noted.

RESULTS

A total of 954 and 280 patients were using beta1-selective and nonselective beta-blockers, respectively. During dobutamine stress echocardiography, the heart rate response was significantly higher, systolic and diastolic blood pressure responses were significantly lower and the double product of heart rate and systolic blood pressure was similar in patients using beta1-selective than in patients using nonselective beta-blockers. In patients with and without new wall motion abnormalities during dobutamine stress echocardiography, a similar cardiac event-free survival was observed irrespective of the selectivity of beta-blockers (P=0.9 and 0.3, respectively).

CONCLUSION

During dobutamine stress echocardiography, heart rate and blood pressure response was different, but the double product was similar in patients using beta1-selective or nonselective beta-blockers, which may explain why the long-term prognostic value of dobutamine stress echocardiography is similar in these two groups.

The effects of combined versus selective adrenergic blockade on left ventricular and systemic hemodynamics, myocardial substrate preference, and regional perfusion in conscious dogs with dilated cardiomyopathy

OBJECTIVES

Given that adverse effects of chronic sympathetic activation are mediated by all three adrenergic receptor subtypes (beta1, beta2, alpha1), we examined the effects of standard doses of carvedilol and metoprolol succinate (metoprolol controlled release/extended release [CR/XL]) on hemodynamics, myocardial metabolism, and regional organ perfusion.

BACKGROUND

Both beta1 selective and combined adrenergic blockade reduce morbidity and mortality in heart failure. Whether there are advantages of one class over the other remains controversial, even in the wake of the Carvedilol Or Metoprolol European Trial (COMET). Similarly, the mechanistic basis for the relative differences is incompletely understood.

METHODS

Thirty-three conscious, chronically instrumented dogs with pacing-induced (240 min(-1) for 4 weeks) dilated cardiomyopathy (DCM) were randomized to carvedilol (25 mg twice daily, Coreg, Glaxo Smith Kline, Research Triangle, North Carolina) or metoprolol succinate (100 mg qd, Toprol XL, Astra Zeneca, Wilmington, Delaware). Left ventricular and systemic hemodynamics, myocardial substrate uptake, and norepinephrine spillover were measured before and after three days of treatment. Regional (renal, hepatic, skeletal muscle) blood flows were measured using neutron-activated microspheres.

RESULTS

Both agents had comparable heart rate effects. However, carvedilol-treated dogs showed significantly greater increases in stroke volume and cardiac output and decreases in left ventricular end-diastolic pressure and systemic vascular resistance. Carvedilol increased renal, hepatic, and skeletal muscle blood flow. Carvedilol increased myocardial glucose uptake and suppressed norepinephrine and glucagon. Carvedilol antagonized the response to exogenous norepinephrine to a greater extent than metoprolol CR/XL.

CONCLUSIONS

At doses inducing comparable heart rate reductions, short-term treatment with carvedilol had superior hemodynamic and metabolic effects compared with metoprolol CR/XL. These data suggest important advantages of blocking all three adrenergic receptor subtypes in DCM.

Carvedilol Exerts More Potent Antiadrenergic Effect than Metoprolol in Heart Failure

BACKGROUND

It is still uncertain whether or not there is a difference between metoprolol and carvedilol for the treatment of congestive heart failure. We attempted to determine the difference between the two beta-blockers in terms of their antiadrenergic effect during exercise in patients with heart failure and their efficacy based on the baseline plasma brain natriuretic peptide concentration.

METHODS

Fifty-three patients with mild to moderate heart failure with a radionuclide left ventricular ejection fraction <40% received open label metoprolol or carvedilol in a randomized fashion. The increase in the heart rate normalized to the increase in the plasma norepinephrine concentration during exercise, was calculated as an index of adrenergic responsiveness during exercise.

RESULTS

The increase in heart rate normalized by the increase in plasma norepinephrine concentration, decreased after the initiation of beta-blockers in the carvedilol group, but not in the metoprolol group. The change in cardiac function was more favorable for carvedilol than metoprolol in patients who exhibited a higher baseline brain natriuretic peptide concentration.

CONCLUSIONS

Carvedilol exerts a more potent antiadrenergic effect than metoprolol during stress in patients with mild to moderate heart failure. Carvedilol appears to be more efficacious than metoprolol in patients who exhibit higher baseline brain natriuretic peptide concentrations. These differences should be kept in mind when selecting appropriate pharmacologic agents in the treatment of heart failure.

A comparative crossover study of the effects of fluvastatin and pravastatin (FP-COS) on circulating autoantibodies to oxidized LDL in patients with hypercholesterolemia

This study compared the effects of fluvastatin and pravastatin on the in vivo oxidation of LDL in a crossover design to evaluate whether or not it is justified to switch between the two statins with regard to serum levels of lipids, lipoproteins, and apolipoproteins (apo), and circulating autoantibodies to oxidized LDL (OxLDL-Ab). Patients with hypercholesterolemia (n = 46) were randomly assigned into groups who received fluvastatin (20 mg/d) or pravastatin (10 mg/d). After 3 months, they were crossed to receive the other statin for another 3 months. Circulating levels of OxLDL-Ab were measured by an OxLDL IgG ELISA test. Fluvastatin and pravastatin similarly decreased serum levels of total cholesterol (TC), LDL-C, and apo B, and increased HDL(2)-C levels. After crossover to the other statin, these lipid parameters were not further changed by either statin. Before crossover, circulating levels of OxLDL-Ab were decreased in patients with fluvastatin treatment, but not in those with pravastatin treatment. After switching from the other statin, both fluvastatin and pravastatin further decreased OxLDL-Ab levels. In conclusion, fluvastatin at 20 mg/d and pravastatin at 10 mg/d are similar with regard to their efficacy in decreasing TC, LDL-C, and apo B levels and increasing HDL(2)-C levels. Fluvastatin lowered circulating levels of OxLDL-Ab, and these effects continued after switching to pravastatin.

Practical considerations of beta-blockade in the management of the post-myocardial infarction patient

Acute myocardial infarction (AMI) is a major cause of death and disability in the United States that affects an estimated total of 1.5 million men and women each year. Despite significant advances in pharmacologic and interventional therapies, 25% of men and 38% of women still die within 1 year of the acute event. Beta-blockers have been shown to significantly decrease the risk of morbidity and mortality in patients after an AMI. National guidelines recommend that all patients with AMI may be started on beta-blocker therapy and continued indefinitely, unless absolutely contraindicated or not tolerated. However, a substantial portion of eligible AMI survivors are not prescribed beta-blockers in the hospital after an acute event or upon hospital discharge. In addition, patients with AMI are often treated with agents whose long-term use has not been shown effective and for which optimal dosing has not been defined. This paper will discuss the background of beta-blocker use for the treatment of AMI, discuss the rationale for choosing specific agents, and present protocols for initiating or switching to evidence-based therapies.

Exchange of β-blockers in heart failure patients. Experiences from the poststudy phase of COMET (the Carvedilol or Metoprolol European Trial)

BACKGROUND

The Carvedilol or Metoprolol European Trial (COMET) reported a significant survival benefit for carvedilol, a beta1-, beta2- and alpha1-blocker, vs. metoprolol tartrate, a beta1-selective blocker, in patients with mild-to-severe chronic heart failure (CHF). Patients on treatment with metoprolol might benefit from switching to carvedilol.

AIM

To investigate the safety and tolerability of switching beta-blockers in CHF.

METHODS

At the end of COMET, the Steering Committee recommended that study medication was stopped without unblinding, and patients were commenced on open-label beta-blockade at a dose equivalent to half the dose of blinded therapy, with subsequent titration to target or maximum tolerated dose. Patients were followed for 30 days.

RESULTS

1321 out of 1440 patients were transitioned to open-label treatment (76.8% to carvedilol). Serious adverse and CHF-related events were respectively 9.4% and 4.7% in those switching from carvedilol to metoprolol and 3.1% and 1.5% in patients switching from metoprolol to carvedilol. Patients who switched from carvedilol to metoprolol showed the highest mortality or hospitalisation rate (12.3%) in comparison with those who switched from metoprolol to carvedilol (3.1%, p<0.001) or who stayed on the same drug (carvedilol: 2.5%, p<0.001; metoprolol: 4.2%, p=0.04). Reducing the initial dose of the second beta-blocker maximised the safety of this strategy. Event rate was higher in patients with more severe heart failure and in those withdrawing from beta-blockade.

CONCLUSION

Our data show that switching beta-blockers is a practical, safe and well-tolerated strategy to optimise treatment of CHF. Patients who switched to carvedilol showed the lowest rate of adverse events. A closer clinical monitoring is recommended during transition in high-risk patients.

Long-term effects of carvedilol or metoprolol on left ventricular function in ischemic and nonischemic cardiomyopathy

Data regarding the effects of beta blockers on left ventricular (LV) function after 12 months are scarce in ischemic and nonischemic cardiomyopathy. Echocardiograms of 72 patients with ischemic and nonischemic cardiomyopathy, who were free of clinical events susceptible to alter LV function while receiving carvedilol or metoprolol for at least 24 months, were prospectively reanalyzed. Twelve months after beta-blocker initiation, LV ejection fraction (EF) increased by > or = 5% in 75% of patients, whereas EF failed to increase by 5% or decreased in the remaining 25%. Over the subsequent 32 months, LVEF increased further in patients who had experienced an initial EF increase by > or = 5%, whereas EF tended to further decrease in patients who had experienced an initial EF increase of <5% or a decrease. Thus, the benefits of carvedilol or metoprolol on LV function are long lasting in patients with ischemic or nonischemic cardiomyopathy who are free of events susceptible to alter LV function while receiving beta blockade.

Critical differences among beta-adrenoreceptor antagonists in myocardial failure: debating the MERIT of COMET

In the United States, carvedilol and metoprolol (tartrate or succinate) are the most commonly employed beta-adrenoreceptor antagonists for the treatment of heart failure. However, use of these agents in patients with heart failure remains extremely low despite overwhelming evidence of their beneficial short- and long-term effects. Because the myocardial pathophysiology associated with heart failure involves not only beta-1 adrenoreceptors but also beta-2 and alpha-1 adrenoreceptors, this indicates a more complex disease process that may require pan-receptor antagonism to provide optimal clinical benefit. Relative to metoprolol (tartrate or succinate), carvedilol represents an extremely complex molecular entity that not only possesses the ability to antagonize all of the principle adrenoreceptors involved in heart failure but also reduces oxidative stress and provides an antiarrhythmic benefit independent of beta-adrenoreceptor antagonism. Taken together, an interesting pharmacologic premise for the superiority of carvedilol relative to metoprolol (tartrate) may exist, but the lack of clinical trials comparing an optimal dose of either extended-release metoprolol (ie, succinate) or immediate-release metoprolol (ie, tartrate) to carvedilol limits the clinical application of the pharmacologic differences between the agents.

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.

Betablockers in heart failure: Carvedilol Safety Assessment (CASA 2-trial)

BACKGROUND

Betablockers are a cornerstone in the treatment of patients with chronic heart failure (CHF). The purpose of the present study was to assess safety and tolerability of carvedilol in CHF-patients.

METHODS

66 general practitioners, who were supervised by a local cardiologist, enrolled 151 CHF-patients. All patients were on standard therapy with ACE-inhibitors and diuretics. Carvedilol treatment was started with 3.125 mg twice daily and slowly uptitrated in 2-week intervals to 2x25 mg per day. Mean follow-up was 12 weeks.

RESULTS

145 of the 151 patients (96%) finished the study according to protocol, six patients were lost to follow-up (4%). 59 patients (41%) experienced minor and nine (6%) serious adverse events. 68 were under maximal therapy with 50 mg daily, 33 received 25 mg, and 15 12.5 mg. Overall tolerability was good and NYHA-class fell significantly from 2.2 to 1.8 (P<0.001). Mean heart rate decreased from 78 to 69 bpm (P<0.001), mean systolic blood pressure from 137 to 132 mmHg (P<0.001) and mean diastolic blood pressure from 80 to 76 mmHg (P<0.001). Quality of life significantly improved under carvedilol with a reduction in the Minnesota living with heart failure score from 1.28 to 0.88 (P<0.001).

CONCLUSIONS

Carvedilol is well tolerated in CHF-patients treated by general practitioners. Serious adverse events and hospitalisations are rare. Thus, carvedilol is a safe drug in the treatment of CHF-patients and can be easily initiated and managed by the general practitioner.

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.

Myocardial beta-1 adrenoceptor down-regulation in aging and heart failure: implications for beta-blocker use in older adults with heart failure

Heart failure is associated with increased sympathetic nervous stimulation that results in down-regulation of myocardial beta-1 receptors. The failing heart might depend more on beta-2 receptors for positive inotropic support than the normal heart. Suppression of both beta-1 and beta-2 adrenoceptors by a non-selective beta-blocker, such as carvedilol, is likely to eliminate the failing heart's much needed inotropic support, resulting in an exacerbation of symptoms. Use of a beta-1 selective blocker, such as metoprolol, on the other hand, is likely to be well tolerated. Unlike carvedilol, the use of metoprolol is associated with up-regulation of beta-1 receptors. The clinical significance of the pharmacodynamic differences between these two beta-blockers in terms of their short-term hemodynamic and long-term beneficial effects is not clearly understood. However, in clinical trials, both carvedilol and metoprolol improved left ventricular function, heart failure symptoms and survival. Both drugs are well tolerated as well. Aging itself is associated with elevated myocardial and serum norepinephrine levels, which is associated with down-regulation of beta-1 receptors. In this article, we reviewed the literature to examine the clinical implications of this dual (age- and heart failure-related) sympathetic stimulation and beta-1 receptor down-regulation on selection of beta-blockers in older adults with heart failure.

Carvedilol but not metoprolol reduces beta-adrenergic responsiveness after complete elimination from plasma in vivo

BACKGROUND

Carvedilol but not metoprolol exhibits persistent binding to beta-adrenergic receptors (beta-ARs) even after washout in cell culture experiments. Here, we determined the significance of this phenomenon on human beta-ARs in vitro and in vivo.

METHODS AND RESULTS

Experiments were conducted on human atrial trabeculae (n=8 to 10 per group). In the presence of metoprolol, isoproterenol potency was reduced compared with controls (P<0.001). In the presence of carvedilol, isoproterenol identified 2 distinct binding sites of high (36+/-6%; -8.8+/-0.4 log mol/L) and low affinity (-6.5+/-0.2 log mol/L). After beta-blocker washout, isoproterenol potency returned to control values in metoprolol-treated muscles, whereas in carvedilol-treated preparations, isoproterenol potency remained decreased (P<0.001 versus control). In vivo studies were performed in 9 individuals receiving metoprolol succinate (190 mg/d) or carvedilol (50 mg/d) for 11 days in a randomized crossover design. Dobutamine stress echocardiography (5 to 40 microg x kg(-1) x min(-1)) was performed before, during, and 44 hours after application of study medication. Beta-blocker medication reduced heart rate, heart rate-corrected velocity of circumferential fiber shortening, and cardiac output compared with baseline (P<0.02 to 0.0001). After withdrawal of metoprolol, all parameters returned to baseline values, whereas after carvedilol, all parameters remained reduced (P<0.05 to 0.001) despite complete plasma elimination of carvedilol.

CONCLUSIONS

Carvedilol but not metoprolol inhibits the catecholamine response of the human heart beyond its plasma elimination. The persistent beta-blockade by carvedilol may be explained by binding of carvedilol to an allosteric site of beta-ARs.

Practical guidelines to optimize effectiveness of beta-blockade in patients postinfarction and in those with chronic heart failure

Antiadrenergic therapy reduces the risks of death and major morbidity in patients postinfarction and in those with chronic heart failure. Despite the common perception, these benefits are not attributable to a class effect, and clinical trials reveal evidence of specific agents that provide clinical advantages. To optimize patient outcome in the postinfarction setting, propranolol or timolol should be used in the setting of preserved ventricular function, and carvedilol should be used in patients with impaired ventricular function, with or without clinical evidence of heart failure. Patients with chronic heart failure are at lower risk of death when treated with carvedilol, which is also associated with a lower incidence of developing diabetes mellitus-related adverse events. This article reviews the scientific evidence for the hierarchy of antiadrenergic agents and addresses practical issues associated with initiation of therapy and long-term management.

Switching between beta blockers in heart failure patients: rationale and practical considerations

The clinical benefit of beta blockade has been proven in a variety of pathologic settings, including hypertension, angina pectoris, acute- and post-myocardial infarction, and congestive heart failure. However, beta blockers do not all share the same clinical outcomes with respect to efficacy or safety in many of these conditions. This is especially true in HF, where differences in reverse remodeling and effects on the periphery may be important differentiating factors leading to improved efficacy. In fact, beta blockers are a heterogeneous group of agents with respect to pharmacology, receptor biology, hemodynamic effects, and tolerability. As cardiovascular disease progresses, the issue of switching from one b blocker to another is an important consideration as to how to optimize the effectiveness of adrenergic blockade. Because of the differences among beta blockers, switching should be conducted in a manner that takes into account pharmacologic differences. For example, the similarities and differences of receptor subtype blockade of the two agents and the potential effects of ancillary properties. Two protocols for switching between carvedilol, a third-generation nonselective agent with vasodilation through alpha1 blockade, and a beta1-selective agent (e.g., metoprolol, atenolol) are described to simplify the process and maximize the safety and tolerability of this procedure. The optimal selection and use of adrenergic-blocking agents in the cardiovascular continuum will assist in providing improved management while minimizing safety and tolerability concerns.

Beta-adrenergic receptor blockers in heart failure

Congestive heart failure is a progressive disease with high morbidity and mortality if left untreated. Standard therapy for patients with systolic left ventricular dysfunction now includes angiotensin-converting enzyme inhibitors and beta blockers. beta Blockers have been demonstrated to decrease mortality, reduce hospitalizations, improve functional class, decrease left ventricular dimensions, and improve ejection fraction in several large-scale, randomized, placebo-controlled trials. In addition to reducing deaths due to progressive heart failure, beta blockers also reduce the incidence of sudden death. Therapy with beta blockers can successfully be initiated in most patients with heart failure if recommended titration schedules are followed. beta Blockers are an important component of medical therapy for all stages of heart failure.

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.

Decreased heart rate recovery after exercise in patients with congestive heart failure: Effect of β-blocker therapy

BACKGROUND

Decreased heart rate recovery (HRR) is a predictor of mortality in patients with coronary artery disease and preserved left ventricular function. We investigated the changes in HRR and assessed the impact of beta-blockade therapy on these parameters in patients with symptomatic congestive heart failure (CHF).

METHODS AND RESULTS

HRR, defined as the difference from peak exercise heart rate (HR) to HR measured at 1, 2, and 3 minutes after maximal exercise test, was studied in 23 stable CHF patients and 12 healthy subjects. Patients with CHF performed a maximal exercise test using a Ramp protocol before and after 6 months of therapy with either metoprolol or carvedilol. Patients with CHF exhibited a significantly attenuated HRR compared with healthy subjects at 1 minute (17.8 +/- 5.8 versus 26.8 +/- 16.2 beats), 2 minutes (34.0 +/- 10.6 versus 48.0 +/- 11.2 bpm) and 3 minutes (41.0 +/- 12.4 versus 60.0 +/-12.4 bpm) after exercise (P<.05 for all parameters). Beta-blocker therapy for 6 months did not significantly improve HRR.

CONCLUSION

HRR is markedly attenuated in stable CHF patients compared with healthy subjects. Long-term beta-blocker therapy appears to cause no significant improvement in HRR up to 3 minutes after maximal exercise.

Different responses to dobutamine in the presence of carvedilol or metoprolol in patients with chronic heart failure

OBJECTIVE

To determine whether patients with congestive heart failure on different beta adrenoreceptor blocking drugs have similar haemodynamic responses to dobutamine.

DESIGN

Single centre, single blind, randomised, two period crossover study comparing carvedilol with metoprolol CR/XL.

PATIENTS

Ten patients with stable chronic congestive heart failure (ejection fraction < 40%) on chronic treatment with metoprolol CR/XL.

METHODS

Patients were treated with carvedilol or metoprolol CR/XL (target dose 50 mg twice daily and 200 mg once daily, respectively) for eight weeks. Stress echocardiography was undertaken at the end of each maintenance period, using dobutamine 5 and 15 microg/kg/min.

RESULTS

No significant haemodynamic differences were seen at rest on the two treatments. There was a more pronounced increase in heart rate and cardiac output during dobutamine infusion when the patients were on metoprolol than when they were on carvedilol. Mean arterial pressure increased significantly when the patients were on carvedilol, and cardiac output increased during low dose dobutamine, without further change during high dose dobutamine. During the dobutamine infusion, there was no significant difference in ejection fraction between carvedilol and metoprolol treatment.

CONCLUSIONS

Patients with congestive heart failure on a non-selective beta adrenoreceptor blocker or beta1 selective blocker responded differently to the inotropic drug dobutamine: the beta1 blockade caused by metoprolol could be counteracted by dobutamine, whereas with carvedilol a low dose of dobutamine increased cardiac output, and a higher dose of dobutamine caused a pressor effect. These findings may be clinically relevant when choosing an inotropic drug.

Expanding role of beta-blockade in the management of chronic heart failure

Although recent advances have been made in the treatment of heart failure, this disease continues to result in significant morbidity and mortality. Among the negative effects associated with progression of heart failure are decline in myocardial reserve, decreased exercise tolerance, decreased contractile function, and altered cardiac gene expression. Guidelines recommend neurohormonal antagonists for treatment and stress the importance of angiotensin-converting enzyme inhibition and beta-blockade in reversing the cardiac remodeling process. beta-Blockade slows or reverses the adverse effects resulting from chronic adrenergic stimulation. Traditionally, beta-blockers were reserved for mild-to-moderate heart failure, based on evidence from large, randomized clinical trials showing their positive effects on myocardial function and clinical outcomes. More recently, clinical data reveal that the agents can be expanded to patients with severe heart failure and those with left ventricular systolic dysfunction after myocardial infarction. Individual beta-blocking agents vary in their pharmacology and dosing requirements. These variations may influence treatment decisions and affect clinical measurements of left ventricular function and ventricular remodeling.