Effect of metoprolol on myocardial function and energetics in patients with nonischemic dilated cardiomyopathy: a randomized, double-blind, placebo-controlled study

Beta-blockers for heart failure: why, which, when, and where

Beta-blockers are a highly effective treatment for patients with all grades of heart failure secondary to LV systolic dysfunction. Beta-blockers are best deployed as a form of tertiary prevention in heart failure but have a very limited role for the treatment of a heart failure crisis. Physicians and patients need to understand the time course of the effects of beta-blocker therapy. The initial effects are often neutral or adverse, though the benefits, at least of carvedilol, may be apparent within days in patients with severe heart failure. Benefits accumulate gradually over a period of weeks to months. Some patience, perseverance, and education are required in order to allow patients to reap the full benefits of beta-blocker therapy for this malignant disease. Initiation of treatment early in the course of the disease maximizes the effectiveness and acceptance of therapy. Trials are under way to determine whether the benefits of beta-blockers extend to patients over 80 years of age and to those with preserved LV systolic function. It is likely that important differences exist between beta-blockers in terms of their clinical benefit, though whether differences exist between the agents that have been reported to be effective so far awaits the outcome of a large clinical trial. It is unclear whether the target doses of beta-blockers currently recommended are optimal.

Ranolazine, a partial fatty acid oxidation (pFOX) inhibitor, improves left ventricular function in dogs with chronic heart failure

BACKGROUND

Abnormalities of energy metabolism are often cited as key elements in the progressive worsening of left ventricular (LV) dysfunction that characterizes the heart failure (HF) state. The present study tested the hypothesis that partial inhibition of fatty acids will ameliorate the hemodynamic abnormalities associated with HF.

METHODS AND RESULTS

Chronic HF (LV ejection fraction 27 +/- 1%) was produced in 13 dogs by intracoronary microembolizations. Hemodynamic and angiographic measurements were made before and 40 minutes after intravenous administration of ranolazine, a partial fatty acid oxidation (pFOX) inhibitor. Ranolazine was administered as an intravenous bolus dose of 0.5 mg/kg followed by a continuous infusion for 40 minutes at a constant rate of 1.0 mg / kg / hr. Ranolazine significantly increased LV ejection fraction (27 +/- 1 versus 36 +/- 2, P =.0001), peak LV +dP/dt (1712 +/- 122 versus 1900 +/- 112 mm Hg/sec, P =.001), and stroke volume (20 +/- 1 versus 26 +/- 1 mL). These improvements occurred in the absence of any effects on heart rate or systemic pressure. In 8 normal healthy dogs, ranolazine had no effect on LV ejection fraction or any other index of LV function.

CONCLUSIONS

In dogs with HF, acute intravenous administration of the pFOX inhibitor ranolazine improves LV systolic function. The absence of any hemodynamic effects of ranolazine in normal dogs suggests that the drug is devoid of any positive inotropic effects and acts primarily by optimizing cardiac metabolism in the setting of chronic HF.

Cardiac-specific overexpression of GLUT1 prevents the development of heart failure attributable to pressure overload in mice

BACKGROUND

Increased rates of glucose uptake and glycolysis have been repeatedly observed in cardiac hypertrophy and failure. Although these changes have been considered part of the fetal gene reactivation program, the functional significance of increased glucose utilization in hypertrophied and failing myocardium is poorly understood.

METHODS AND RESULTS

We generated transgenic (TG) mice with cardiac-specific overexpression of insulin-independent glucose transporter GLUT1 to recapitulate the increases in basal glucose uptake rate observed in hypertrophied hearts. Isolated perfused TG hearts showed a greater rate of basal glucose uptake and glycolysis than hearts isolated from wild-type littermates, which persisted after pressure overload by ascending aortic constriction (AAC). The in vivo cardiac function in TG mice, assessed by echocardiography, was unaltered. When subjected to AAC, wild-type mice exhibited a progressive decline in left ventricular (LV) fractional shortening accompanied by ventricular dilation and decreased phosphocreatine to ATP ratio and reached a mortality rate of 40% at 8 weeks. In contrast, TG-AAC mice maintained LV function and phosphocreatine to ATP ratio and had <10% mortality.

CONCLUSIONS

We found that increasing insulin-independent glucose uptake and glycolysis in adult hearts does not compromise cardiac function. Furthermore, we demonstrate that increasing glucose utilization in hypertrophied hearts protects against contractile dysfunction and LV dilation after chronic pressure overload.

The cardioprotective role of beta-blockers in patients with diabetes mellitus

This paper reviews the role of beta-blockers in the prevention of cardiovascular morbidity and mortality in patients with diabetes mellitus. There is good evidence from randomized controlled trials that beta-blockers, in particular the lipophilic agents, substantially reduce cardiovascular mortality and morbidity. However, hitherto beta-blockers have been underused in diabetic patients, perhaps because of perceived risks of beta-blocker therapy. Reappraisal of the evidence suggests that the traditional reluctance to use beta-blockers in this group is based on fears of adverse effects that are largely unfounded.

Energy metabolism in the normal and failing heart: potential for therapeutic interventions

The chronically failing heart has been shown to be metabolically abnormal, in both animal models and in patients. Little data are available on the rate of myocardial glucose, lactate and fatty acid metabolism and oxidation in heart failure patients, thus at present, it is not possible to draw definitive conclusions about cardiac substrate preference in the various stages and manifestations of the disease. Normal cardiac function is dependent on a constant resynthesis of ATP by oxidative phosphorylation in the mitochondria. The healthy heart gets 60-90% of its energy for oxidative phosphorylation from fatty acid oxidation, with the balance from lactate and glucose. There is some indication that compensated NYHA Class III heart failure patients have a significantly greater rate of lipid oxidation, and decreased glucose uptake and carbohydrate oxidation compared to healthy age-matched individuals, and that therapies that acutely switch the substrate of the heart away from fatty acids result in improvement in left ventricular function. Clinical studies using long-term therapy with beta-adrenergic receptor antagonists show improved left ventricular function that corresponds with a switch away from fatty acid oxidation towards more carbohydrate oxidation by the heart. These findings suggest that chronic manipulation of myocardial substrate oxidation toward greater carbohydrate oxidation and less fatty acid oxidation may improve ventricular performance and slow the progression of left ventricular dysfunction in heart failure patients. At present, this intriguing hypothesis requires further evaluation.

Longitudinal myocardial contraction improves early during titration with metoprolol CR/XL in patients with heart failure

OBJECTIVE

To investigate diastolic and systolic left ventricular recovery during titration with metoprolol CR/XL (controlled release/extended release).

DESIGN

Placebo run in, followed by an open study.

SETTING

University hospital.

PATIENTS

14 patients with chronic heart failure.

INTERVENTIONS

Metoprolol CR/XL titrated from 12.5 mg once daily to 200 mg once daily.

MAIN OUTCOME MEASURES

M mode recordings of atrioventricular (AV) plane displacement, Doppler measurement of transmitral flow and pulmonary venous flow, two dimensional ejection fraction, and measurement of venous plasma concentration of noradrenaline. Patients were investigated after 2, 4, 6, and 24 weeks of treatment.

RESULTS

A reduction of heart rate was observed on the first dose (12.5 mg once daily), from a mean (SD) of 74 (11) to 67 (11) beats/min, p < 0.05. This was accompanied by prominent effects on AV plane filling parameters, including an increase in early diastolic filling period from 87 (28) to 105 (33) ms (p < 0.05), and in the lateral AV plane fractional shortening from 8.7 (2.7)% to 10.2 (2.8)% (p < 0.05). An early trend towards improvement in global systolic left ventricular function was also seen, although this was not significant until six weeks. Ejection fraction increased from 33 (7.5)% to 38 (11)% (p < 0.05).

CONCLUSIONS

First effects of left ventricular recovery during beta blocker treatment were seen in recordings of longitudinal performance, as expressed by AV plane displacement. Doppler flow dynamics as well as global systolic recovery appeared several weeks later, emphasising the importance of longitudinal performance in evaluating left ventricular function.

Mechanisms whereby rapid RV pacing causes LV dysfunction: perfusion-contraction matching and NO

Incessant tachycardia induces dilated cardiomyopathy in humans and experimental models; mechanisms are incompletely understood. We hypothesized that excessive chronotropic demands require compensatory contractility reductions to balance metabolic requirements. We studied 24 conscious dogs during rapid right ventricular (RV) pacing over 4 wk. We measured hemodynamic, coronary blood flow (CBF), myocardial O(2) consumption (MVO(2)) responses, myocardial nitric oxide (NO) production, and substrate utilization. Early pacing (6 h) resulted in decreased heart rate (HR)-adjusted coronary blood flow (CBF), MVO(2) (CBF/beat: 0.33 +/- 0.02 to 0.19 +/- 0.01 ml, P < 0.001, MVO(2)/beat: 0.031 +/- 0.002 to 0.016 +/- 0.001 ml O(2), P < 0.001), and contractility [left ventricular (LV) first derivative pressure (dP/dt)/LV end-diastolic diameter (EDD): 65 +/- 4 to 44 +/- 3 mmHg x s(-1) x mm(-1), P < 0.01], consistent with flow-metabolism-function coupling, which persisted over the first 72 h of pacing (CBF/beat: 0.15 +/- 0.01 ml, MVO(2)/beat: 0.013 +/- 0.001 ml O(2), P < 0.001). Thereafter, CBF per beat and MVO(2) per beat increased (CBF/beat: 0.25 +/- 0.01 ml, MVO(2)/beat: 0.021 +/- 0.001 ml O(2) at 28 days, P < 0.01 vs. 72 h). Contractility declined [(LV dP/dt)/LVEDD: 19 +/- 2 mmHg x s(-1) x mm(-1), P < 0.0001], signifying flow-function mismatch. Cardiac NO production, endothelial NO synthase expression, and fatty acid utilization decreased in late phase, whereas glycogen content and lactate uptake increased. Incessant tachycardia induces contractile, metabolic, and flow abnormalities reflecting flow-function matching early, but progresses to LV dysfunction late, despite restoration of flow and metabolism. The shift to flow-function mismatch is associated with impaired myocardial NO production.

Nonselective versus selective beta-adrenergic receptor blockade in congestive heart failure: differential effects on sympathetic activity

BACKGROUND

Activation of the sympathetic nervous system has important prognostic implications in chronic heart failure. Nonselective versus selective beta-adrenergic receptor antagonists may have differential effects on norepinephrine release from nerve terminals mediated by prejunctional beta(2)-adrenergic receptors.

METHODS AND RESULTS

Thirty-six patients with chronic heart failure were randomized to the nonselective beta-blocker carvedilol or the selective beta-blocker metoprolol (double-blind). Measurements of hemodynamics and cardiac and systemic norepinephrine spillover as well as microneurographic recordings of muscle sympathetic nerve traffic were made before and after 4 months of therapy. In the carvedilol group (n=17), there were significant reductions in both total body (-1.7+/-0.5 nmol/min, P<0.01) and cardiac norepinephrine spillover (-87+/-29 pmol/min, P<0.01). By contrast, in the metoprolol group (n=14), there were no significant changes in total body or cardiac norepinephrine spillover. Responses in the carvedilol group were significantly different from those observed in the metoprolol group (P<0.05). Both agents caused a reduction in heart rate and increases in pulse pressure, although mean arterial pressure did not change. Importantly, microneurographic measures of sympathetic nerve traffic to skeletal muscle did not change in either group.

CONCLUSIONS

Therapy with carvedilol caused significant decreases in systemic and cardiac norepinephrine spillover, an indirect measure of norepinephrine release. Such changes were not observed in patients treated with metoprolol. There was no effect of either agent on sympathetic efferent neuronal discharge to skeletal muscle. These findings suggest that carvedilol, a nonselective beta-blocker, caused its sympathoinhibitory effect by blocking peripheral, prejunctional beta-adrenergic receptors.

Regression of left ventricular remodeling in chronic heart failure: Comparative and combined effects of captopril and carvedilol

BACKGROUND

This study evaluated the independent and combined effects of captopril and carvedilol on left ventricular remodeling in chronic heart failure. Although angiotensin-converting enzyme inhibitors and b-blockers are known to attenuate the remodeling process in chronic heart failure, a direct comparison of these agents has not been performed.

METHODS

We investigated 57 patients with mild to moderate chronic heart failure (48 ischemic, 9 nonischemic) who were randomized in a double-blind fashion to treatment with carvedilol or captopril at maximum doses of 25 mg twice daily for 3 months, followed by 3 months of combined treatment. Serial echocardiography, right heart catheterization, and treadmill exercise testing were performed at baseline, 3 months, and 6 months. After exclusions, 49 patients were evaluated during monotherapy and 48 during combination therapy.

RESULTS

Carvedilol monotherapy produced significant reductions in end-systolic volume, leading to a greater median increase in ejection fraction compared with captopril monotherapy (4.7% vs 1.5%, respectively; P <.05). Each drug caused similar reductions in left ventricular mass, chamber sphericity, and pulmonary artery wedge pressure during monotherapy and combined treatment. Adjunctive treatment with carvedilol produced a trend toward a greater increase in ejection fraction (4.3% vs 2.7%, respectively; P not significant) and significantly greater reductions in the wall thickening score index than with captopril (0.25 vs 0.08, respectively; P =.04).

CONCLUSIONS

Although angiotensin-converting enzyme inhibitor therapy did not alter left ventricular volume, treatment with carvedilol was associated with reductions in chamber volume; both drugs reduced left ventricular mass and sphericity. These beneficial effects on remodeling may help to explain the relative prognostic benefits of these therapies.

Systematic review of the impact of beta blockers on mortality and hospital admissions in heart failure

Heart failure is a common condition that carries a high burden of mortality and morbidity. Several randomised trials have evaluated the effects of beta blockers in heart failure. This paper gives a systematic overview of published randomised trials of beta blockers in heart failure using standard methods. In all, 22 randomised controlled trials were identified with a total of 10480 patients, and an average of 11 months of treatment. The average age was 61 years and 4% were female. Most studies excluded patients with severe heart failure. Death rates in patients randomised to receive beta blockers compared to controls were 458/5657 (8.0%) and 635/4951 (12.8%) respectively, odds ratio 0.63, 95% CI 0.55-0.72, P<0.00001. Similar reductions were observed for hospital admissions for worsening heart failure (11.3 vs. 17.1%, respectively, odds ratio 0.63) and for the composite outcome of death or heart-failure hospital admission (19.4 vs. 26.9%, respectively, odds ratio 0.66). These results show that beta blockers reduce the risk of mortality or the need for heart-failure hospital admission by approximately one third. Absolute reductions of 5-6% in event rates were observed over approximately 1 year of treatment period. These important benefits should be implemented as a priority, since treatment with beta blockers is inexpensive and heart failure carries a high risk of death and disability. Further information on the effect of beta blockers in elderly patients and women would be helpful.

Prognostic evaluation of neurohumoral plasma levels before and during beta-blocker therapy in advanced left ventricular dysfunction

OBJECTIVES

The study assessed the relative predictive potency of neurohumoral factors in patients with advanced left ventricular (LV) dysfunction during neurohumoral blocking therapy.

BACKGROUND

The course of heart failure is characterized by progressive LV deterioration associated with an increase in cardiac (natriuretic peptides) and predominantly extracardiac (norepinephrine, big endothelin [big ET]) hormone plasma levels.

METHODS

Plasma hormones were measured at baseline and months 3, 6, 12 and 24 in 91 patients with heart failure (left ventricular ejection fraction [LVEF] <25%) receiving 40 mg enalapril/day and double-blind atenolol (50 to 100 mg/day) or placebo. After the double-blind study phase, patients were followed up to four years. Stepwise multivariate regression analyses were performed with 10 variables (age, etiology, LVEF, symptom class, atenolol/placebo, norepinephrine, big ET, log aminoterminal atrial natriuretic peptide, log aminoterminal B-type natriuretic peptide [N-BNP] and log B-type natriuretic peptide [BNP]). During the study, the last values prior to patient death were used, and in survivors the last hormone level, New York Heart Association class and LVEF at month 24 were used.

RESULTS

Thirty-one patients died from a cardiovascular cause during follow-up. At baseline, log BNP plasma level (x2 = 13.9, p = 0.0002), treatment allocation (x2 = 9.5, p = 0.002) and LVEF (x2 = 5.6, p = 0.017) were independently related to mortality. During the study, log BNP plasma level (x2 = 21.3, p = 0.0001) remained the strongest predictive marker, with LVEF (x2 = 11.2, p = 0.0008) log N-BNP plasma level (x2 = 8.9, p = 0.0027) and treatment allocation (x2 = 6.4, p = 0.0109) providing additional independent information.

CONCLUSIONS

In patients with advanced LV dysfunction receiving high-dose angiotensin-converting enzyme inhibitors and beta-blocker therapy BNP and N-BNP plasma levels are both independently related to mortality. This observation highlights the importance of these hormones and implies that they will likely emerge as a very useful blood test for detection of the progression of heart failure, even in the face of neurohumoral blocking therapy.

In patients with chronic atrial fibrillation and left ventricular systolic dysfunction, restoration of sinus rhythm confers substantial benefit

STUDY OBJECTIVES

To evaluate the benefit of sinus rhythm (SR) restoration in patients with chronic controlled atrial fibrillation (AF) and left ventricular systolic dysfunction (LVSD).

DESIGN

Prospective case-control study on the short-term outcome (6 to 9 months) of clinical and echocardiographic variables following attempted cardioversion.

SETTING

Outpatient clinic of a university hospital.

PATIENTS

Fifteen men and 5 women, ranging in age from 40 to 76 years, who had chronic controlled (mean [+/- SD] ventricular rate, 82 +/- 10 beats/min) AF and left ventricular fractional shortening (LVFS) of < 28% at baseline. Control was provided by retrospective paired echocardiographic examinations of six AF patients, plus the study cases with potentially unsuccessful cardioversion or early recurrence of AF.

INTERVENTIONS

Attempt to restore SR with amiodarone or electrical countershock.

MEASUREMENTS AND RESULTS

Conversion was attained in 17 patients, but AF recurred early in 4 patients, 3 of whom had proven ischemic LVSD. In the 13 patients with sustained SR, LVFS increased from 20 +/- 4% to 31 +/- 6% (p < 0.0001). In contrast, no changes were detected in the control group (n = 13). This improvement was paralleled by decreases in left ventricular (LV) end-diastolic dimension (from 55 +/- 7 to 51 +/- 6 mm; p = 0.014), LV mass (from 181 +/- 28 to 159 +/- 37 g; p = 0.015), and left atrial diameter (from 45 +/- 9 mm to 42 +/- 7; p = 0.003). A marked decrease in heart rate (from 82 +/- 9 to 64 +/- 5 beats/min; p < 0.0001) and a reduction in New York Heart Association functional class (from 2.3 +/- 0.9 to 1.2 +/- 0.4; p = 0.0007) also were observed in patients with sustained SR but not among subjects in the control group.

CONCLUSIONS

Even when adequate control of the ventricular rate has been achieved, the LV function of patients with chronic AF greatly improves after restoration and maintenance of SR.

Comparative effects of carvedilol and metoprolol on left ventricular ejection fraction in heart failure: results of a meta-analysis

BACKGROUND

Both metoprolol and carvedilol improve cardiac function and prolong survival in patients with heart failure. Carvedilol has broader antiadrenergic effects than metoprolol, but it is not clear whether this characteristic is associated with greater benefits on cardiac function during long-term treatment.

STUDY DESIGN

We performed a meta-analysis of all 19 randomized controlled trials of carvedilol or metoprolol that measured left ventricular ejection fraction before and after an average of 8.3 +/- 0.1 months of treatment in 2184 patients with chronic heart failure. The mean daily doses were 58 +/- 1 mg of carvedilol and the equivalent of 162 +/- 1 mg of extended-release metoprolol. In the 15 placebo-controlled trials, the mean ejection fraction increased more in the trials of carvedilol than in the trials of metoprolol (placebo-corrected increases of +0.065 and +0.038, respectively), P = .0002. In the 4 active-controlled trials that compared metoprolol directly with carvedilol, the mean ejection fraction also increased more in the carvedilol groups than in the metoprolol groups (+0.084 on carvedilol and +0.057 on metoprolol, respectively), P = .009. The difference in favor of carvedilol in the active-controlled trials was nearly identical to the difference observed in the placebo-controlled trials and was apparent in patients with and without coronary artery disease.

CONCLUSION

Long-term treatment with carvedilol produces greater effects on left ventricular ejection fraction than metoprolol when both drugs are prescribed in doses similar to those that have been shown to prolong life.

Beta-blocking in heart failure patients. Balancing the evidence

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

Myocardial Free Fatty Acid and Glucose Use After Carvedilol Treatment in Patients With Congestive Heart Failure

Background —Use of β-adrenoreceptor blockade in the treatment of heart failure has been associated with a reduction in myocardial oxygen consumption and an improvement in myocardial energy efficiency. One potential mechanism for this beneficial effect is a shift in myocardial substrate use from increased free fatty acid (FFA) oxidation to increased glucose oxidation.

Methods and Results —We studied the effect of carvedilol therapy on myocardial FFA and glucose use in 9 patients with stable New York Heart Association functional class III ischemic cardiomyopathy (left ventricular ejection fraction ≤35%) using myocardial positron emission tomography studies and resting echocardiograms before and 3 months after carvedilol treatment. Myocardial uptake of the novel long chain fatty acid metabolic tracer 14(R, S)-[ 18 F]fluoro-6-thia-heptadecanoic acid ([ 18 F]-FTHA) was used to determine myocardial FFA use, and [ 18 F]fluoro-2-deoxy-glucose ([ 18 F]-FDG) was used to determine myocardial glucose use. After carvedilol treatment, the mean myocardial uptake rate for [ 18 F]-FTHA decreased (from 20.4±8.6 to 9.7±2.3 mL · 100 g –1 · min –1 ; P <0.005), mean fatty acid use decreased (from 19.3±7.0 to 8.2±1.8 μmoL · 100 g –1 · min –1 ; P <0.005), the mean myocardial uptake rate for [ 18 F]-FDG was unchanged (from 1.4±0.4 to 2.4±0.8 mL · 100 g –1 · min –1 ; P =0.14), and mean glucose use was unchanged (from 11.1±3.1 to 18.7±6.0 μmoL · 100 g –1 · min –1 ; P =0.12). Serum FFA and glucose concentrations were unchanged, and mean left ventricular ejection fraction improved (from 26±2% to 37±4%; P <0.05).

Conclusions —Carvedilol treatment in patients with heart failure results in a 57% decrease in myocardial FFA use without a significant change in glucose use. These metabolic changes could contribute to the observed improvements in energy efficiency seen in patients with heart failure.

Practical aspects of using beta-adrenergic blockade in systolic heart failure

Heart failure exacts a severe human and public health toll. In the United States, heart failure afflicts approximately 5 million patients and is responsible for or contributes to 3 million hospitalizations and 300,000 deaths yearly. Physicians can have a major impact on this disease by using effective agents for the treatment of heart failure (particularly angiotensin-converting enzyme [ACE] inhibitors and beta blockers), yet the actual clinical use of these drugs (especially the use of beta blockers by primary physicians) is disappointingly low. Many physicians appear to be reluctant to prescribe beta blockers for two reasons. First, they are concerned about the potential interference of beta blockers with important compensatory mechanisms that support the failing heart and fear that such interference may lead to clinical deterioration. Second, they fail to identify patients with heart failure (especially those with mild or moderate symptoms) or regard such patients as being too well to require additional treatment. These reasons should no longer be used as excuses to avoid the use of these drugs, given the persuasive evidence that beta blockers can improve symptoms and prolong life in patients with heart failure. Instead, physicians must recognize that long-term activation of the sympathetic nervous system primarily exerts deleterious (rather than compensatory) effects in patients with heart failure and that these actions can be antagonized effectively and safely by the appropriate use of beta-blocking drugs.

Current role of beta-adrenergic blockers in the management of chronic heart failure

Long-term activation of the sympathetic nervous system exerts adverse biologic effects that are mediated through alpha(1), beta(1) and beta(2) receptors and that contribute importantly to the progression of heart failure. As a result, beta blockers are no longer considered to be contraindicated for use in these patients but instead now play a critical role in the successful management of chronic heart failure. Beta blockers have been evaluated in >15,000 patients with heart failure who have participated in placebo-controlled trials. The results of these studies indicate that, like angiotensin-converting enzyme (ACE) inhibitors, long-term treatment with beta blockers can lessen symptoms and improve clinical status and can reduce the risk of death as well as the combined risk of death or hospitalization. The database supporting the use of beta blockers is now as persuasive (and arguably more persuasive) than the database supporting the use of ACE inhibitors in heart failure (which comprises about 7,000 patients). Yet, the benefits of beta blockers are seen in patients already receiving ACE inhibitors, suggesting that combined blockade of two neurohormonal systems (renin-angiotensin system and sympathetic nervous system) can produce additive effects.

Beta-blocker therapy in heart failure

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

Mechanisms of Carvedilol Action in Human Congestive Heart Failure

Abstract —The precise mechanism by which β-adrenoceptor blockers exert their beneficial actions in patients with heart failure remains unclear. Several possibilities have been proposed, including heart rate reduction, β2-adrenoceptor–mediated modulation of catecholamine release, antagonism of the receptor-mediated toxic actions of norepinephrine on the myocardium, and favorable effects on myocardial energetics. In the present study we evaluated the effect of 3 months of carvedilol therapy on hemodynamics, total systemic and cardiac norepinephrine spillover (isotope dilution method), and myocardial metabolism (myocardial oxygen consumption and carbon dioxide release) in 10 patients with severe congestive heart failure. Although carvedilol treatment was associated with a significant improvement in left ventricular ejection fraction (17±1% to 28±3%; P <0.01) and left ventricular stroke work (87±13 to 119±21 g · m per beat; P <0.05), this effect was unrelated to changes in total systemic or cardiac norepinephrine spillover. The rise in left ventricular stroke work was accompanied by a modest rise in myocardial oxygen consumption per beat (0.33±0.04 to 0.42±0.04; P =0.05), although contractile efficiency was unchanged. The favorable effects of carvedilol on ventricular function in the failing heart are not explained by alterations in norepinephrine release or by changes in myocardial contractile efficiency.

Beta-blocker treatment in heart failure

Heart failure treatment has markedly changed during the last few decades, with demonstration of benefit of afterload reduction by vasodilator therapy and introduction of the concept of the deleterious consequences of the neuro-hormonal compensatory stimulation. Blockade of beta-adrenergic receptors, initially contra-indicated in heart failure, provide a marked reduction of mortality and morbidity in combination with diuretics and angiotensin-converting enzyme inhibitors, as demonstrated in many clinical trials. We performed a review of all clinical trials that compare beta-blockers vs. placebo in chronic heart failure. Beta-blockers with different pharmacological profiles have been tested, mainly metoprolol, bisoprolol, bucindolol and carvedilol. With progressive dose increment, tolerance of such treatment was generally good, left ventricular function improved, hospitalisations for heart failure were less frequent and mortality was reduced. The meta-analysis of the 16 randomised trials, with at least one death in each treatment group, provides a 24% relative risk reduction for such hospitalisations (95% CI=19%-29%) and 22% reduction for mortality (95% CI=16%-28%). Heterogeneity of beta-blocker effect for mortality was found and related to the non-significant benefit obtained in the BEST trial with bucindolol. When such a trial is excluded, the effect model analysis shows that relative risk reduction (beta-blocker induced benefit) is constant whatever the severity of the disease. The mechanism of beta-blocker induced benefit remains unclear, but is at least partly related to left ventricular function improvement and prevention of severe ventricular arrhythmias. In conclusion, beta-blocker treatment has become an established therapy for heart failure, in combination with diuretics and ACE inhibitors. Complementary informations will be needed to clarify the mechanism of benefit and to define the best therapeutic strategy according to the individual characteristics of patients with heart failure.

Left ventricular inotropic reserve and right ventricular function predict increase of left ventricular ejection fraction after beta-blocker therapy in nonischemic cardiomyopathy

OBJECTIVES

The purpose of this study was to determine whether higher left ventricular inotropic reserve, defined as the increase in left ventricular ejection fraction (LVEF) in response to intravenous dobutamine infusion, or other ventriculographic variables predict the increase in LVEF after beta-blocker therapy in patients with nonischemic cardiomyopathy (NICM).

BACKGROUND

Long-term beta-blocker therapy increases LVEF in some patients with NICM. Other than dose, there are no definite predictors of LVEF increase.

METHODS

Thirty patients with LVEF < or = 0.35 and NICM underwent assessment of LVEF at rest and after a 10-min intravenous infusion of dobutamine at 10 microg/kg/min, using equilibrium radionuclide ventriculography. Age was 49 +/- 11 years, 33% women, functional class 2.6 +/- 0.5, duration of chronic heart failure 3.2 +/- 2.9 years, LVEF 0.21 +/- 0.07, left ventricular end-diastolic volume index 180 +/- 64 ml/m2. Right ventricular ejection fraction (RVEF) was abnormal in 37%. Mean dobutamine-induced augmentation of LVEF (DoALVEF) was 0.12 +/- 0.08. Patients were started on one of three beta-blockers (carvedilol, bucindolol or metoprolol) and the dose was advanced to the maximum tolerated.

RESULTS

Left ventricular ejection fraction, reassessed 7.4 +/- 5.9 months after maximum beta-blocker dose was reached, increased to 0.34 +/- 0.13 (p = 0.0006). The following baseline variables correlated with improvement of LVEF: DoALVEF (p = 0.001), RVEF (p = 0.005), systolic blood pressure at end of dobutamine infusion (p = 0.02) and dose of beta-blocker (p = 0.07). In a multivariate analysis, only DoALVEF (p = 0.0003) and RVEF (p = 0.002) were predictive of the increase in LVEF.

CONCLUSIONS

Patients with nonischemic cardiomyopathy who have higher left ventricular inotropic reserve and normal RVEF derive higher increase in LVEF from beta-blocker therapy.

Heart failure therapy at the turn of the century

Major changes in the treatment of heart failure have occurred in the last fifty years that have had a dramatic effect on its morbidity and mortality. Over two hundred years have passed since the demonstration of the benefit of digitalis in heart failure to the development of potent loop diuretics. The observation that vasodilators could improve both cardiac function and mortality led to the investigation of the Angiotensin Converting Enzyme Inhibitors (ACEI). Although these agents had significant vasodilator properties, their major benefit appears to be related to their ability to effect remodeling of the failing left ventricle. The most recent randomized clinical trials demonstrate that Beta Adrenergic Blocking agents can provide an incremental effect on both mortality and morbidity when added to therapy with ACEI. Although these agents have improved the outlook for the heart failure patient, they have had very little effect on the improvement of left ventricular function. Future research must be directed at methods to deal with this issue by either changing the contractile properties of the cardiomyocyte by pharmacologic or electrical therapy or by transplanting functional cells that can increase the number of functioning contractile units.

Beta-blockade in heart failure: selective versus nonselective agents

Controlled clinical trials performed in more than 13 000 patients have, to date, consistently shown the beneficial effects of long term beta-adrenoceptor antagonist (beta-blocker) therapy in patients with chronic heart failure. It is not clear whether this represents a class effect or whether it is specific only to some agents. Beneficial effects on the prognosis of patients with mild to moderate heart failure have been shown with metoprolol, bisoprolol, and carvedilol. These beta-blockers, however, differ in their pharmacologic characteristics. Metoprolol and bisoprolol are selective for beta(1)-adrenergic receptors and are devoid of ancillary properties. Carvedilol, at a dosage of 50 mg/day, blocks all beta(1)-, beta(2)-, and alpha(1)-adrenergic receptors, and it has associated antiproliferative and antioxidant activities. These differences cause a varied acute hemodynamic response, with a reduction in cardiac output and a tendency toward a rise in pulmonary wedge pressure with selective agents and no change in cardiac output and a slight decrease in pulmonary pressures with carvedilol. Accordingly, when the therapy is started, the most frequent adverse effects are worsening heart failure with metoprolol and bisoprolol, and hypotension and dizziness with carvedilol. It remains controversial whether these differences also influence the long term effects of therapy. Carvedilol may provide a more comprehensive blockade of the cardiac adrenergic drive than selective beta-blockers because it does not upregulate beta(1)-adrenergic receptors, blocks all adrenergic receptors and decreases cardiac norepinephrine release. These properties may lead to a larger increase in left ventricular function and a lack of improvement in maximal exercise capacity with carvedilol, compared with selective beta-blockers. It is, however, unclear whether these differences also influence patient outcome. The long term effects of different beta-blockers on prognosis are currently being compared in the Carvedilol or Metoprolol European Trial (COMET) in which more than 3000 patients with chronic heart failure have been randomized in a 1 : 1 ratio to receive metoprolol or carvedilol.

Left ventricular or biventricular pacing improves cardiac function at diminished energy cost in patients with dilated cardiomyopathy and left bundle-branch block

BACKGROUND

Left ventricular or biventricular pacing/stimulation can acutely improve systolic function in patients with dilated cardiomyopathy (DCM) and intraventricular conduction delay by resynchronizing contraction. Most heart failure therapies directly enhancing systolic function do so while concomitantly increasing myocardial oxygen consumption (MVO(2)). We hypothesized that pacing/stimulation, in contrast, incurs systolic benefits without raising energy demand.

METHODS AND RESULTS

Ten DCM patients with left bundle-branch block (ejection fraction 20+/-3%, QRS duration 179+/-3 ms, mean+/-SEM) underwent cardiac catheterization to measure ventricular and aortic pressure, coronary blood flow, arterial-coronary sinus oxygen difference (DeltaAVO(2)), and MVO(2). Data were measured under sinus rhythm or with left ventricular or biventricular pacing/stimulation at the same heart rate. These results were then contrasted to intravenous dobutamine (n=7) titrated to match systolic changes during LV pacing. Systolic function rose quickly and substantially from LV pacing (18+/-4% rise in arterial pulse pressure, which correlates with cardiac output, and 43+/-6% increase in dP/dt(max); both P<0.01). However, DeltaAVO(2) and MVO(2) declined -4+/-2% and -8+/-6.5%, respectively (both P<0.05). Similar results were obtained with biventricular activation. In contrast, dobutamine raised dP/dt(max) 37+/-6%, accompanied by a 22+/-11% rise in per-beat MVO(2) (P<0.05 versus pacing).

CONCLUSIONS

Ventricular resynchronization by left ventricular or biventricular pacing/stimulation in DCM patients with left bundle-branch block acutely enhances systolic function while modestly lowering energy cost. This should prove valuable for treating DCM patients with basal dyssynchrony.

Antiremodeling effects on the left ventricle during beta-blockade with metoprolol in the treatment of chronic heart failure

OBJECTIVES

The purpose of the study was to investigate the effects of beta1-blockade on left ventricular (LV) size and function for patients with chronic heart failure.

BACKGROUND

Large-scale trials have shown that a marked decrease in mortality can be obtained by treatment of chronic heart failure with beta-adrenergic blocking agents. Possible mechanisms behind this effect remain yet to be fully elucidated, and previous studies have presented insignificant results regarding suspected LV antiremodeling effects.

METHODS

In this randomized, placebo-controlled and double-blind substudy to the Metoprolol CR/XL Randomized Intervention Trial in Heart Failure (MERIT-HF), 41 patients were examined with magnetic resonance imaging three times in a six-month period, assessing LV dimensions and function.

RESULTS

Decreases in both LV end-diastolic volume index (150 ml/m2 at baseline to 126 ml/m2 after six months, p = 0.007) and LV end-systolic volume index (107 ml/m2 to 81 ml/m2, p = 0.001) were found, whereas LV ejection fraction increased in the metoprolol CR/XL group (29% to 37%, p = 0.005). No significant changes were seen in the placebo group regarding these variables. Left ventricular stroke volume index remained unchanged, whereas LV mass index decreased in both groups (175 g/m2 to 160 g/m2 in the placebo group [p = 0.005] and 179 g/m2 to 164 g/m2 in the metoprolol CR/XL group [p = 0.011).

CONCLUSIONS

This study is the first randomized study to demonstrate that the beta1-blocker metoprolol CR/XL has antiremodeling effects on the LV in patients with chronic heart failure and consequently provides an explanation for the highly significant decrease in mortality from worsening heart failure found in the MERIT-HF trial.

Beta-adrenergic blockers in the treatment of pediatric heart failure

Beta-adrenergic blocking agents for the treatment of chronic congestive heart failure in adults have gained wide acceptance. Although the exact mechanism of their effect is still not entirely clear, the preponderance of data support the hypothesis that the primary mechanism of action of beta-blocking agents in chronic heart failure is to prevent and reverse adrenergically-mediated intrinsic myocardial dysfunction and remodeling. Large, multicenter trials in adults with chronic congestive heart failure have definitively shown that beta-blockers improve left ventricular ejection fraction, symptoms, and survival when compared to placebo. Although experience with beta-blockers in children is limited, anecdotal evidence suggests that children with chronic congestive heart failure may also benefit from this therapy. Large trials in children are currently in the planning stages in order to attempt to determine the indications, dosages, and optimal use of beta-blockers in children with chronic congestive heart failure.

Chronic therapy with metoprolol attenuates cardiomyocyte apoptosis in dogs with heart failure

OBJECTIVES

The purpose of this study was to determine if therapy with beta-blockade is associated with reduced cardiomyocyte apoptosis.

BACKGROUND

Chronic treatment with beta-adrenergic blocking agents has been shown to improve left ventricular (LV) ejection fraction and attenuate progressive LV remodeling in heart failure (HF). Cardiomyocyte apoptosis has also been shown to occur in the failing heart.

METHODS

Moderate HF was produced in 14 dogs by intracoronary microembolizations. Dogs were randomized to three months therapy with metoprolol (MET, 25 mg twice daily, n = 7) or to no therapy at all (n = 7). At the end of three months, dogs were sacrificed, and nuclear DNA fragmentation (nDNAf), a marker of apoptosis, was assessed in LV tissue using the TUNEL assay. The number of cardiomyocytes with positive nDNAf labeling per 1,000 was quantified in LV regions bordering old infarcts and in regions remote from infarcts. Endonuclease activity and expression of the antiapoptotic protein Bcl-2 and the proapoptotic proteins Bax and caspase-3 were also evaluated in LV tissue.

RESULTS

The number of nDNAf events per 1,000 cardiomyocytes was lower in dogs treated with MET compared with untreated dogs with HF in the border regions (0.35 +/- 0.07 vs. 5.32 +/- 0.77, p < 0.001) as well as the remote regions (0.07 +/- 0.05 vs. 0.39 +/- 0.12, p < 0.05). Endonuclease activity was also significantly lower in MET-treated compared with untreated dogs (25 +/- 3 vs. 37 +/- 2 ng [3H]DNA rendered soluble/min/mg protein). Western blotting for Bcl-2, Bax and caspase-3 showed increased expression of Bcl-2, decreased expression of caspase-3 and no change in Bax in MET-treated compared with untreated dogs.

CONCLUSIONS

Chronic therapy with MET attenuates cardiomyocyte apoptosis in dogs with moderate HF. Attenuation of ongoing cardiomyocyte loss through apoptosis may be one mechanism through which beta-blockers elicit their benefits in HF.

Effects of beta-blockers on neurohormonal activation in patients with congestive heart failure

The effect of beta-adrenoceptor antagonists (beta-blockers) on neurohormonal activation in patients with congestive heart failure has been the subject of study in numerous small clinical trials. Short term therapy with beta-blockers is associated with a variable acute neurohormonal response which may be determined by the pharmacology of the agent under study and the baseline characteristics of the patient population. Long term therapy with beta-blockers devoid of intrinsic sympathomimetic activity (partial agonist activity) is associated with evidence of decreased plasma markers of activation of the sympathetic nervous system, the renin-angiotensin system, and endothelin-1. Beta1-selective and nonselective beta-blockers appear to be associated with evidence of decreased neurohormonal activation, with differential effects on beta-adrenoceptor density. Agents with partial agonist activity appear to differ from pure antagonists, with some studies reporting evidence of increased neurohormonal activation. The mechanisms by which beta-blockers reduce neurohormonal activation and the clinical relevance of changes in adrenergic function to their use in the treatment of heart failure require further investigation.

Effect of concomitant digoxin and carvedilol therapy on mortality and morbidity in patients with chronic heart failure

We retrospectively performed stepwise logistic regression analysis on 1,509 patients with chronic heart failure in 4 multicenter United States studies and 1 Australia-New Zealand study to examine the effect of digoxin in patients randomized to carvedilol or placebo. Patients receiving digoxin had more advanced heart failure, the incidence of hospitalization for any cause and the combination of all-cause death and all-cause hospitalization were the same in the digoxin versus no-digoxin groups.

Role of beta blockers in congestive heart failure

Prolonged activation of the adrenergic nervous system has adverse consequences on the cardiovascular system in patients with congestive heart failure. Beta adrenergic receptor-blocker therapy modifies these deleterious effects. Beta blockers have been shown to improve myocardial function and survival when used in conjunction with conventional treatment with diuretics, angiotensin-converting enzyme inhibitors, and digoxin. Beta blocker therapy in mild-to-moderate heart failure should not be delayed because it causes some reversal of both neurohormonal compensatory mechanisms and the deleterious myocardial remodeling process. This paper reviews the beneficial effects of beta adrenergic receptor-blocker therapy on the pathophysiology, symptoms, left ventricular function, morbidity, and mortality in patients with congestive heart failure. (c)2000 by CHF, Inc.

The effects of beta(1)-blockade on oxidative metabolism and the metabolic cost of ventricular work in patients with left ventricular dysfunction: A double-blind, placebo-controlled, positron-emission tomography study

BACKGROUND

The mechanism for the beneficial effect of beta-blocker therapy in patients with left ventricular (LV) dysfunction is unclear, but it may relate to an energy-sparing effect that results in improved cardiac efficiency. C-11 acetate kinetics, measured using positron-emission tomography (PET), are a proven noninvasive marker of oxidative metabolism and myocardial oxygen consumption (MVO(2)). This approach can be used to measure the work-metabolic index, which is a noninvasive estimate of cardiac efficiency.

METHODS AND RESULTS

The aim of this study was to determine the effect of metoprolol on oxidative metabolism and the work-metabolic index in patients with LV dysfunction. Forty patients (29 with ischemic and 11 with nonischemic heart disease; LV ejection fraction <40%) were randomized to receive metoprolol or placebo in a treatment protocol of titration plus 3 months of stable therapy. Seven patients were not included in analysis because of withdrawal from the study, incomplete follow-up, or nonanalyzable PET data. The rate of oxidative metabolism (k) was measured using C-11-acetate PET, and stoke volume index (SVI) was measured using echocardiography. The work-metabolic index was calculated as follows: (systolic blood pressure x SVI x heart rate)/k. No significant change in oxidative metabolism occurred with placebo (k=0.061+/-0.022 to 0.054+/-0.012 per minute). Metoprolol reduced oxidative metabolism (k=0.062+/-0. 024 to 0.045+/-0.015 per minute; P:=0.002). The work-metabolic index did not change with placebo (from 5.29+/-2.46 x 10(6) to 5.14+/-2. 06 x 10(6) mm Hg. mL/m(2)), but it increased with metoprolol (from 5. 31+/-2.15 x 10(6) to 7.08+/-2.36 x 10(6) mm Hg. mL/m(2); P:<0.001).

CONCLUSIONS

Selective beta-blocker therapy with metoprolol leads to a reduction in oxidative metabolism and an improvement in cardiac efficiency in patients with LV dysfunction. It is likely that this energy-sparing effect contributes to the clinical benefits observed with beta-blocker therapy in this patient population.

Improvement in cardiac function and free fatty acid metabolism in a case of dilated cardiomyopathy with CD36 deficiency

A 27-year-old man diagnosed as having dilated cardiomyopathy (DCM) without myocardial accumulation of 123I-beta-methyl-iodophenylpentadecanoic acid, and he was found to have type I CD36 deficiency. This abnormality of cardiac free fatty acid metabolism was also confirmed by other methods: 18F-fluoro-2-deoxyglucose positron emission tomography, measurements of myocardial respiratory quotient and cardiac fatty acid uptake. Although the type I CD36 deficiency was reconfirmed after 3 months, the abnormal free fatty acid metabolism improved after carvedilol therapy and was accompanied by improved cardiac function. Apart from a cause-and-effect relationship, carvedilol can improve cardiac function and increase free fatty acid metabolism in patients with both DCM and CD36 deficiency.

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.

Beta blockade in patients with congestive heart failure. Why, who, and how

In patients with CHF, physicians should aim to treat the LV dysfunction, not just the CHF symptoms. LV dysfunction is a chronic disease that is usually progressive, even when it seem compensated. The risk of sudden death or progressive CHF is very real. Adding a beta blocker to the treatment regimen while the disease is still compensated or after resolution of an acute exacerbation can stabilize or reverse the LV dysfunction and improve survival. Beta blockade is now a vital part of the standard of care for most patients with LV dysfunction.

Deactivation of the sympathetic nervous system in patients with chronic congestive heart failure

In this article, we review the basic biology, signal transduction pathways, and clinical pharmacology associated with cardiac beta-adrenergic receptors (beta-ARs) in the context of the use of beta-blocking agents in patients with chronic congestive heart failure. Adrenergic receptors, particularly the beta-AR subtypes (beta(1)-AR and beta(2)-AR), are known to play a critical role in the modulation of cardiac function, providing for both "adaptive" and "maladaptive" compensatory changes. In the context of exercise or self-preservation, the adrenergic nervous system, acting via beta-ARs permits an appropriately rapid, highly-dynamic increase in cardiac function. Conversely, in individuals with chronic congestive heart failure, the sustained, heightened activation of adrenergic nervous system, as manifested by increases in circulating catecholamines, results in down- regulation and desensitization of myocardial beta-ARs, and potentially, significant myocardial damage. A number of recent clinical trials have demonstrated a marked mortality benefit from using beta-blocking agents such as metoprolol and carvedilol in patients with heart failure. The pharmacologic properties of several of these drugs and some of the specifics of their usefulness and limitations are discussed herein.

Effect of beta-blocker on left ventricular function and natriuretic peptides in patients with chronic heart failure treated with angiotensin-converting enzyme inhibitor

To evaluate whether or not beta-blockers can improve the condition of patients with heart failure treated with a combination of diuretics, digitalis and angiotensin-converting enzyme inhibitor (ACEI), 52 patients with chronic heart failure who have been treated with ACEI for more than 6 months were enrolled. They were divided into 2 groups: 26 patients continued the same therapy another 6 months or more (group A), and 26 patients were given oral metoprolol for 6 months or more, in addition to the ACEI (group B). Echocardiographic parameters and atrial and brain natriuretic peptides (ANP, BNP) were measured. The left ventricular dimensions at end-diastole and end-systole were significantly decreased and fractional shortening was significantly increased in group B after 6 months' treatment with the beta-blocker, but these parameters remained unchanged in group A. Plasma levels of both ANP and BNP were significantly decreased in group B, but remained unchanged in group A. These results indicate that concomitant beta-blocker therapy can improve left ventricular function and attenuate plasma ANP and BNP levels in patients with chronic heart failure treated with ACEI.

Beta-blockade therapy in chronic heart failure: diastolic function and mitral regurgitation improvement by carvedilol

BACKGROUND

In patients with chronic heart failure, the use of carvedilol therapy induces clinical and hemodynamic improvement. However, although the benefits of this beta-blocker have been established in patients with chronic heart failure, the mechanisms underlying them and the changes in left ventricular systolic function, diastolic function, and mitral regurgitation during long-term therapy remain unclear.

OBJECTIVE

To identify the clinical and functional effects of carvedilol, focusing on diastolic function and mitral regurgitation variations.

METHODS

Forty-five consecutive patients with chronic heart failure (ejection fraction 24% +/- 7%), 17 with dilated ischemic and 28 with nonischemic cardiomyopathy, were treated with carvedilol (mean dose 44 +/- 30 mg) and matched for clinical (New York Heart Association functional class and heart failure duration) and hemodynamic (cardiac index and pulmonary wedge pressure) characteristics to a control group. Clinical and echocardiographic variables were measured in the 2 groups at baseline and after 6 months and the results compared.

RESULTS

After 6 months of treatment with carvedilol, left ventricular ejection fraction had increased from 24% +/- 7% to 29% +/- 9% (P <.0001); this change was caused by a reduction in end-systolic volume index (106 +/- 41 vs 93 +/- 37 mL/m(2); P <. 0001). Deceleration time of early diastolic filling increased (134 +/- 74 vs 196 +/- 63 ms; P <.0001). Seventeen of the 27 patients with demonstrated improvement of left ventricular diastolic filling moved from having a restrictive filling pattern to having a normal or pseudonormal left ventricular filling pattern. In the control group, no significant changes in deceleration time of early diastolic filling were found (139 +/- 74 vs 132 +/- 45 ms; P = not significant). The effective regurgitant orifice area decreased significantly in the carvedilol group but not in the control group. These changes were associated with a significant reduction of the mitral regurgitant stroke volume in the carvedilol group (50 +/- 25 vs 16 +/- 13 mL; P <.0001) but not in the control group (57 +/- 29 vs 47 +/- 24 mL; P = not significant). These changes of mitral regurgitation were closely associated with significant improvement of forward aortic stroke volume (r = -.57, P <.0001). These findings were not observed in patients in the control group.

CONCLUSIONS

The results of this study show that long-term carvedilol therapy in patients with chronic heart failure was able to prevent or partially reverse progressive left ventricular dilatation. The effects on left ventricular remodeling were associated with a concomitant recovery of diastolic reserve and a decrease of mitral regurgitation, which have been demonstrated to be powerful prognostic predictors in such patients. Overall these findings provide important insights into the pathophysiologic mechanisms by which carvedilol improves the clinical course of patients with chronic heart failure.

Effects of carvedilol on left ventricular regional wall motion in patients with heart failure caused by ischemic heart disease. Australia-New Zealand Heart Failure Research Collaborative Group

BACKGROUND

Beta-blocker therapy has been shown to improve left ventricular (LV) ejection fraction and reduce LV volumes in patients with heart failure caused by ischemic heart disease. However, the possible mechanisms of this improvement and the effects of such treatment on regional wall motion have not been established. In a substudy of the Australia-New Zealand trial of carvedilol in patients with heart failure caused by ischemic heart disease, the effects of treatment on LV regional wall motion were assessed using 2-dimensional echocardiography.

METHODS AND RESULTS

One hundred nineteen patients from 10 centers were included on this substudy. Patients were randomly assigned to treatment with carvedilol or placebo. Echocardiography was performed before randomization and after 6 and 12 months of treatment. LV regional wall motion was assessed using a semiquantitative scoring system. LV wall motion score index (WMSI) was reduced from 2.40 to 2.29 after 6 and 12 months in the carvedilol group and remained unchanged in the placebo group (2-tailed P = .005, carvedilol vs placebo). The percentage of myocardium with normal function also significantly improved with carvedilol treatment.

CONCLUSIONS

Carvedilol improved LV regional WMSI in patients with heart failure caused by ischemic heart disease. These results indicate a mechanism by which beta-blocker therapy may benefit patients with heart failure and are consistent with an intrinsic improvement in LV function after treatment with carvedilol.

Effect of beta-blocker therapy on severe ventricular arrhythmias in patients with idiopathic dilated cardiomyopathy

Beta-blocker therapy has been shown to improve cardiac function and prognosis in patients with idiopathic dilated cardiomyopathy (DCM). However, whether beta-blockers reduce severe ventricular arrhythmias and sudden cardiac death has not been clarified. The present study was designed to investigate the effects of beta-blockers on non-sustained ventricular tachycardia (VT) and sudden cardiac death in patients with DCM. Sixty-five patients with DCM treated with diuretics, digitalis and angiotensin-converting enzyme inhibitors were assigned to receive beta-blockers (n = 33) or not (n = 32). Mean follow-up was 53+/-30 months. The echocardiographic indices of cardiac function, the incidence of non-sustained VT on Holter monitoring electrocardiograms, and sudden cardiac death rate were compared between the 2 groups. Comparable improvement in cardiac function on echocardiograms was found in the 2 treatment groups. The patient group treated with beta-blockers showed a significant reduction in the prevalence of VT (from 43 to 15%, p<0.05) and the development of new episodes of VT (5 vs. 16%) compared to the group without beta-blockers. The sudden cardiac death rate did not differ between the 2 groups. The results of the present study suggest that beta-blockers are effective in reducing severe ventricular arrhythmias in patients with DCM.

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

BACKGROUND

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

METHODS AND RESULTS

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

CONCLUSIONS

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

beta-blockers in heart failure: recently completed and ongoing clinical trials

beta-Blockers have emerged as an important therapy in patients with symptomatic left ventricular systolic dysfunction. Early studies demonstrated that beta-blocker therapy improved left ventricular function, reduced neurohumoral activity and reduced heart failure symptoms in these patients. While none of these small studies demonstrated a significant benefit in terms of overall survival, several meta-analyses suggested that beta-blocker therapy could, in fact, reduce mortality in patients with left ventricular systolic dysfunction and mild to moderate heart failure symptoms (New York Heart Association class II or III). Three large, recently completed, trials have confirmed the benefit of beta-blockade in these patients. This report reviews some of the initial clinical studies of beta-blockade in heart failure, examines the findings of the three large multicentre trials and other relevant research. Finally, ongoing trials designed to assess the relative efficacy of different beta-blockers and evaluate the utility of beta-blockade in specific subsets of patients with heart failure are discussed.

Beta-blockers for congestive heart failure: what is the current consensus?

Despite the availability of angiotensin converting enzyme (ACE) inhibitors for patients with congestive heart failure (CHF), mortality and morbidity remains unacceptably high. CHF is thought to progress as a result of activation of endogenous neurohormonal systems which are activated by the initial myocardial injury. The 2 neurohormonal systems which seem to be important in CHF are the sympathetic nervous system (SNS), and the renin-angiotensin-aldosterone system (RAAS). While stimulation of the SNS has important circulatory support functions in the short term, long term activation appears to have deleterious effects on cardiac function and outcomes. The purpose of this article is to review the literature on the use of beta-blockers in patients with CHF. The published randomised clinical trials of beta-blockers in patients with CHF have shown very promising effects on mortality and morbidity. Several systematic overviews of these trials also suggest beneficial effects on mortality, hospitalisation for CHFE need for transplant, and ejection fraction. The effect of beta-blockers on exercise tolerance. New York Heart Association Function Class (NYHA-FC) and quality of life remain equivocal. The recent presentation of the results from several large-scale trials which were terminated early because of significant survival benefit, has removed any concern over the robustness of the mortality data. Available evidence suggests that a wide variety of patients with CHF, including the elderly, should be considered for beta-blocker therapy. Caution is warranted in the initiation and titration of therapy, as symptoms of CHF may transiently worsen. Whether all beta-blockers are equally efficacious remains unknown.

Metoprolol CR/XL in patients with heart failure: A pilot study examining the tolerability, safety, and effect on left ventricular ejection fraction

BACKGROUND

This study was designed to investigate the tolerability, safety, and effect on left ventricular function of a new long-acting preparation of metoprolol, metoprolol succinate (CR/XL).

METHODS AND RESULTS

Sixty patients were randomly assigned with a 2:1 ratio, drug versus placebo, administered with a gradually increasing dose of 12.5 to 150 mg of blinded medication during an 8-week period and continued for 6 months. The average peak dose achieved was 99 mg and 132 mg in the metoprolol succinate and placebo groups, respectively. The drug was well tolerated and there was no significant difference in drug withdrawals, New York Heart Association class, or quality of life assessment. The increase in left ventricular ejection fraction measure at baseline and 6 months measured by radioisotopic ventriculography was greater in the metoprolol succinate group (27. 5% to 36.3%) than in the placebo group (26% to 27.9%) (P <.015). Examination of serial Holter electrocardiographic recordings indicate that metoprolol succinate therapy was associated with a significant (P <.05) decrease in total ventricular ectopy at 8 weeks of therapy and a decrease in ventricular couplets and nonsustained ventricular tachycardia at 8 through 26 weeks of therapy. No changes were observed in plasma norepinephrine during therapy except a transitory significant (P <.05) increase in N terminal proatrial natriuretic factor at 8 weeks in the metoprolol succinate group.

CONCLUSIONS

This study indicates that treatment with metoprolol succinate for a 6-month period is safe and well tolerated and is associated with an increase in left ventricular ejection fraction and a decrease in ventricular ectopic beats.