Angiotensin-converting enzyme inhibition and beta-adrenoceptor blockade regress established ventricular remodeling in a canine model of discrete myocardial damage

A Retinoic Acid Receptor β 2 Agonist Improves Cardiac Function in a Heart Failure Model

We previously demonstrated that the selective retinoic acid receptor (RAR) β 2 agonist AC261066 reduces oxidative stress in an ex vivo murine model of ischemia/reperfusion. We hypothesized that by decreasing oxidative stress and consequent fibrogenesis, AC261066 could attenuate the development of contractile dysfunction in post-ischemic heart failure (HF). We tested this hypothesis in vivo using an established murine model of myocardial infarction (MI), obtained by permanent occlusion of the left anterior descending coronary artery. Treating mice with AC261066 in drinking water significantly attenuated the post-MI deterioration of echocardiographic indices of cardiac function, diminished remodeling, and reduced oxidative stress, as evidenced by a decrease in malondialdehyde level and p38 mitogen-activated protein kinase expression in cardiomyocytes. The effects of AC261066 were also associated with a decrease in interstitial fibrosis, as shown by a marked reduction in collagen deposition and α-smooth muscle actin expression. In cardiac murine fibroblasts subjected to hypoxia, AC261066 reversed hypoxia-induced decreases in superoxide dismutase 2 and angiopoietin-like 4 transcriptional levels as well as the increase in NADPH oxidase 2 mRNA, demonstrating that the post-MI cardioprotective effects of AC261066 are associated with an action at the fibroblast level. Thus, AC261066 alleviates post-MI cardiac dysfunction by modulating a set of genes involved in the oxidant/antioxidant balance. These AC261066 responsive genes diminish interstitial fibrogenesis and remodeling. Since MI is a recognized major cause of HF, our data identify RARβ 2 as a potential pharmacological target in the treatment of HF. SIGNIFICANCE STATEMENT: A previous report showed that the selective retinoic acid receptor (RAR) β 2 agonist AC261066 reduces oxidative stress in an ex vivo murine model of ischemia/reperfusion. This study shows that AC261066 attenuates the development of contractile dysfunction and maladaptive remodeling in post-ischemic heart failure (HF) by modulating a set of genes involved in oxidant/antioxidant balance. Since myocardial infarction is a recognized major cause of HF, these data identify RARβ 2 as a potential pharmacological target in the treatment of HF.

Mechanical Unloading in Heart Failure

Myocardial injury induces significant changes in ventricular structure and function at both the cellular and anatomic level, leading to ventricular remodeling and subsequent heart failure. Unloading left ventricular pressure has been studied in both the short-term and long-term settings, as a means of preventing or reversing cardiac remodeling. In acute myocardial infarction, cardiac unloading is used to reduce oxygen demand and limit infarct size. Research has demonstrated the benefits of short-term unloading with mechanical circulatory support devices before reperfusion in the context of acute myocardial infarction with cardiogenic shock, and a confirmatory trial is ongoing. In chronic heart failure, ventricular unloading using mechanical circulatory support can reverse many of the cellular and anatomic changes that accompany ventricular remodeling. Ongoing research is evaluating the ability of left ventricular assist devices to promote myocardial recovery and remission from clinical heart failure.

Pathophysiology of Myocardial Infarction

Myocardial infarction is defined as sudden ischemic death of myocardial tissue. In the clinical context, myocardial infarction is usually due to thrombotic occlusion of a coronary vessel caused by rupture of a vulnerable plaque. Ischemia induces profound metabolic and ionic perturbations in the affected myocardium and causes rapid depression of systolic function. Prolonged myocardial ischemia activates a "wavefront" of cardiomyocyte death that extends from the subendocardium to the subepicardium. Mitochondrial alterations are prominently involved in apoptosis and necrosis of cardiomyocytes in the infarcted heart. The adult mammalian heart has negligible regenerative capacity, thus the infarcted myocardium heals through formation of a scar. Infarct healing is dependent on an inflammatory cascade, triggered by alarmins released by dying cells. Clearance of dead cells and matrix debris by infiltrating phagocytes activates anti-inflammatory pathways leading to suppression of cytokine and chemokine signaling. Activation of the renin-angiotensin-aldosterone system and release of transforming growth factor-β induce conversion of fibroblasts into myofibroblasts, promoting deposition of extracellular matrix proteins. Infarct healing is intertwined with geometric remodeling of the chamber, characterized by dilation, hypertrophy of viable segments, and progressive dysfunction. This review manuscript describes the molecular signals and cellular effectors implicated in injury, repair, and remodeling of the infarcted heart, the mechanistic basis of the most common complications associated with myocardial infarction, and the pathophysiologic effects of established treatment strategies. Moreover, we discuss the implications of pathophysiological insights in design and implementation of new promising therapeutic approaches for patients with myocardial infarction.

The relationship between the MMP system, adrenoceptors and phosphoprotein phosphatases

The MMPs and their inhibitors [tissue inhibitor of MMPs (TIMPs)] form the mainstay of extracellular matrix homeostasis. They are expressed in response to numerous stimuli including cytokines and GPCR activation. This review highlights the importance of adrenoceptors and phosphoprotein phosphatases (PPP) in regulating MMPs in the cardiovascular system, which may help explain some of the beneficial effects of targeting the adrenoceptor system in tissue remodelling and will establish emerging crosstalk between these three systems. Although α- and β-adrenoceptor activation increases MMP but decreases TIMP expression, MMPs are implicated in the growth stimulatory effects of adrenoceptor activation through transactivation of epidermal growth factor receptor. Furthermore, they have recently been found to catalyse the proteolysis of β-adrenoceptors and modulate vascular tone. While the mechanisms underpinning these effects are not well defined, reversible protein phosphorylation by kinases and phosphatases may be key. In particular, PPP (Ser/Thr phosphatases) are not only critical in resensitization and internalization of adrenoceptors but also modulate MMP expression. The interrelationship is complex as isoprenaline (ISO) inhibits okadaic acid [phosphoprotein phosphatase type 1/phosphoprotein phosphatase type 2A (PP2A) inhibitor]-mediated MMP expression. While this may be simply due to its ability to transiently increase PP2A activity, there is evidence for MMP-9 that ISO prevents okadaic acid-mediated expression of MMP-9 through a β-arrestin, NF-κB-dependent pathway, which is abolished by knock-down of PP2A. It is essential that crosstalk between MMPs, adrenoceptors and PPP are investigated further as it will provide important insight into how adrenoceptors modulate cardiovascular remodelling, and may identify new targets for pharmacological manipulation of the MMP system.

Chronic coronary disease in the post-COURAGE Era: a new paradigm

In recent decades, there have been substantial declines in the morbidity and mortality rates of cardiovascular disease. Nonetheless, cardiologists have sometimes been slow to amend prevailing concepts and alter established clinical strategies even when compelling new evidence comes to light. Recent studies have underscored the systemic nature of coronary artery disease, its early age at onset, and its high prevalence in the general population. Prevention and treatment approaches should fully incorporate these concepts. Furthermore, prevention of the most devastating complications of chronic coronary artery disease-sudden death and acute coronary events-should be given the highest priority.

Inhibition of NF-κB induces regression of cardiac hypertrophy, independent of blood pressure control, in spontaneously hypertensive rats

The transcription factor nuclear factor (NF)-κB plays a leading role in cardiac hypertrophy associated with heart failure, but whether it is involved in cardiac mass reduction is not known. We evaluated whether inhibiting the NF-κB cascade with pyrrolidine dithiocarbamate (PDTC) in spontaneously hypertensive rats (SHRs) and age-matched Wistar-Kyoto rats (WKYs) affected hypertrophy. We measured NF-κB signaling components [NF-κB translocation, IκBα, p65, mRNA and protein levels, and IκB kinase-β (IKKβ) activity] at 12 and 36 wk in WKYs and SHRs and at 10 wk in PDTC-treated rats ( n = 9). NF-κB activation was also evaluated in rats treated for 10 wk with captopril or hydralazine alone or with either drug plus PDTC. All components were increased in SHRs compared with WKYs. After PDTC treatment, NF-κB activity was inhibited, and heart weight-to-body weight ratio in SHRs was significantly attenuated (3.52 ± 0.04 to 3.32 ± 0.05 mg/kg). Captopril treatment significantly reduced cardiac mass (3.5 vs. 3.05 mg/kg; n = 9) and inhibited NF-κB activity (169.71 ± 5.70 to 106.7 ± 12.44). Hydralazine had no effect on cardiac mass (3.5 vs. 3.42 mg/kg) or NF-κB activity (169.71 ± 5.70 to 155.52 ± 6.11). Hydralazine plus PDTC reduced blood pressure (191.16 ± 1.7 to 158.5 ± 2.36 mmHg) and inhibited NF-κB activity (169.71 ± 5.70 to 97.29 ± 3.65). Our data suggest that 1) cardiac hypertrophy in SHRs is partly due to NF-κB activation, 2) inhibition of NF-κB activity by PDTC parallels regression of hypertrophy, and 3) regression of hypertrophy is partly due to inhibition of NF-κB activity, independent of hypertension. The relationship between NF-κB activity and cardiac remodeling is causal, not coincidental.

Effect of carvedilol on diastolic function in patients with diastolic heart failure and preserved systolic function. Results of the Swedish Doppler-echocardiographic study (SWEDIC)

AIM

The purpose of this study was to investigate the effects of carvedilol on diastolic function (DF) in heart failure patients with preserved left ventricular (LV) systolic function and abnormal DF.

PATIENTS AND METHODS

We randomised 113 patients with diastolic heart failure (DHF) (symptomatic, with normal systolic LV function and abnormal DF) into a double blind multi-centre study. The patients received either carvedilol or matching placebo in addition to conventional treatment. After uptitration, treatment was continued for 6 months. Two-dimensional and Doppler echocardiography were used for quantification of LV function at baseline and at follow-up. Four different DF variables were evaluated by Doppler echocardiography: mitral flow E:A ratio, deceleration time (DT), isovolumic relaxation time (IVRT) and the ratio of systolic/diastolic pulmonary venous flow velocity (pv-S/D). Primary endpoint was change in the integrated quantitative assessment of all four variables during the study.

RESULTS

Ninety-seven patients completed the study. A mitral flow pattern reflecting a relaxation abnormality was recorded in 95 patients. There was no effect on the primary endpoint, although a trend towards a better effect in carvedilol treated patients was noticed in patients with heart rates above 71 beats per minute. At the end of the study, there was a statistically significant improvement in E:A ratio in patients treated with carvedilol (0.72 to 0.83) vs. placebo (0.71 to 0.76), P<0.05.

CONCLUSIONS

Treatment with carvedilol resulted in a significant improvement in E:A ratio in patients with heart failure due to a LV relaxation abnormality. E:A ratio was found to be the most useful variable to identify diastolic dysfunction in this patient population. This effect was observed particularly in patients with higher heart rates at baseline.

Prevention and Reversal of LV Remodeling with Neurohormonal Inhibitors

Left ventricular (LV) remodeling refers to alterations in ventricular mass, chamber size, and shape that result from myocardial injury, pressure, or volume overload. Numerous studies have demonstrated that LV remodeling correlates with the incidence of heart failure and death, supporting a causative role for remodeling in heart failure progression. Heart failure trials have shown that neurohormonal antagonists, including angiotensin-converting enzyme (ACE) inhibitors and beta-adrenergic receptor blockers (beta blockers), reduce remodeling in parallel with improved clinical outcomes. Existing data favor using angiotensin II type 1 (AT1) receptor antagonists (or "ARBs"), although their anti-remodeling effects are less well established. Recently, mineralocorticoid receptor antagonists have gained substantial interest based on favorable clinical trial results, although data regarding their effects on remodeling are limited. Thus, an optimal medical regimen to prevent or limit LV remodeling in patients with LV dysfunction should include both an ACE inhibitor and beta-adrenergic receptor antagonist, irrespective of the degree of LV dysfunction and symptom status. For patients intolerant to ACE inhibitors, an AT1 receptor antagonist should be substituted. An aldosterone antagonist should be administered to patients with severe, New York Heart Association class III to IV heart failure who have normal or only mildly impaired renal function, or to those patients with depressed LV function following an acute myocardial infarction. Through the aggressive pharmacologic inhibition of both the renin-angiotensin-aldosterone and sympathetic nervous systems, progressive LV remodeling can be prevented or hindered, thereby favorably altering the natural history of the heart failure syndrome.

Can natriuretic peptides be used for the diagnosis of diastolic heart failure?

Many patients with heart failure have stiff hearts with an increased wall thickness and small volumes leading to diastolic dysfunction. Different definitions for diastolic heart failure have been proposed but today there is no generally accepted definition and there are few large controlled studies telling us how it should be managed. Natriuretic peptides (BNP or NT-proBNP) might be used to detect patients with diastolic dysfunction especially in those patients having a restrictive filling pattern or pseudo-normalised mitral flow pattern and in those, who are symptomatic. However, patients with relaxation abnormalities and mild symptoms or asymptomatic may have normal levels of the natriuretic peptides indicating no or only slight elevation of the left ventricular filling pressures. Thus low levels cannot be used as a rule out diagnosis of diastolic dysfunction.

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.

The cardiac support device and the myosplint: treating heart failure by targeting left ventricular size and shape

Left ventricular (LV) remodeling occurs in patients with heart failure and is associated with poor long-term outcome. Two important components of this remodeling process are progressive LV dilation and LV shape changes, the latter manifested by increased LV chamber sphericity. This brief review describes two passive mechanical devices that were developed to prevent the progressive LV dilation and shape changes that occur during the evolution of heart failure. One such device is the Cardiac Support Device ([CSD] CorCap; Acorn Cardiovascular, St Paul, MN) and the other is the Myosplint (Myocor, Maple Grove, MN). Studies in dogs with coronary microembolization-induced heart failure have shown that the CSD prevents progressive LV dilation, increases LV ejection fraction, lowers LV wall stress, and attenuates LV chamber sphericity. Safety and feasibility studies in patients with heart failure have shown that the CSD is safe. The same studies have provided strong efficacy trends that are consistent with those seen in experimental animals. Studies in dogs with rapid pacing induced heart failure showed that the Myosplint device can reshape the LV leading to reduced LV volumes, increased ejection fraction, and reduced wall stress. Safety and feasibility studies of the Myosplint device in humans are limited and trends are not as yet easily discerned. Final conclusions on the clinical effectiveness of these devices must await completion of randomized clinical trials. These trials should provide the first tests in humans of the hypothesis that limiting LV remodeling alone can improve long-term outcome and quality of life in patients with heart failure.

Heart failure: a hemodynamic disorder complicated by maladaptive proliferative responses

Heart failure has traditionally been viewed as a hemodynamic syndrome characterized by fluid retention, high venous pressure, and low cardiac output. Over the past decade, however, it has become clear that because of deterioration and progressive dilatation (remodeling) of the diseased heart, this is also a rapidly fatal syndrome. The importance of prognosis came to be appreciated when clinical trials showed that therapy which initially improves such functional abnormalities, as high venous pressure and low cardiac output, often fail to improve survival, and that some drugs which improve hemodynamics worsen long-term prognosis. The latter is true for most vasodilators which, in spite of alleviating the adverse short-term consequences of high afterload, shorten survival. Notable exceptions are ACE inhibitors, whose vasodilator effects do not explain their ability to prolong survival; instead, these drugs slow both deterioration and remodeling of the failing heart. Inotropic agents, while providing immediate relief of symptoms, generally shorten long-term survival, whereas beta-blockers slow deterioration and remodeling, and reduce mortality. Aldosterone antagonists exert beneficial effects on prognosis that are not easily explained by their diuretic effects, but instead can be explained by their ability to inhibit signaling pathways that stimulate maladaptive hypertrophy, remodeling, apoptosis and other deleterious responses that cause deterioration of the failing heart. These and other findings demonstrate that heart failure is more than a hemodynamic disorder; these patients suffer from maladaptive proliferative responses that cause cardiac cell death and progressive dilatation that play a key role in determining the poor prognosis in this syndrome.

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

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

Combination of therapeutic apheresis and therapeutic ventricular assistance for end-stage heart failure patients

Dilated cardiomyopathy is a cardiac disease of unknown origin which is characterized by the gradual development of cardiac failure associated with four-chamber dilatation of the heart. Heart transplantation has been considered as the last resort for this disease. However, some patients who received support with a ventricular assist device (VAD) as a bridge-to-transplantation and then recovered without transplantation have been reported. This new concept of treating heart failure is termed bridge-to-recovery. A VAD can inhibit the heart failure compensatory mechanisms by extreme ventricular unloading. Also, heart failure is a complex neurohormonal/autocrine-paracrine syndrome, and these mechanisms consecutively lead to inflammatory response by proinflammatory cytokines; interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), interleukin-2 (IL-2), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha). Furthermore, the existence of anti-beta1-adrenoceptor autoantibodies (A-beta1-AABs) in a patient with dilated cardiomyopathy has been reported. These proinflammatory cytokines and this antibody accelerate a ventricular remodeling and a contractile dysfunction over the long term. Apheresis can also inhibit the vicious cycle in heart failure by removing the factors that are produced by activated neurohormonal/autocrine-paracrine compensatory mechanisms. Therefore, we propose that the combined therapies, therapeutic VAD and therapeutic apheresis, will provide a prominent outcome for a patient who is suffering from end-stage heart failure.

Reverse remodeling and enhanced adrenergic reserve from passive external support in experimental dilated heart failure

OBJECTIVES

We sought to test the efficacy of a passive elastic containment device to reverse chronic chamber remodeling and adrenergic down-regulation in the failing heart, yet still maintaining preload reserve.

BACKGROUND

Progressive cardiac remodeling due to heart failure is thought to exacerbate underlying myocardial dysfunction. In a pressure-volume analysis, we tested the impact of limiting progressive cardiac dilation by an externally applied passive containment device on both basal and adrenergic-stimulated function in failing canine hearts.

METHODS

Ischemic dilated cardiomyopathy was induced by repeated intracoronary microembolizations in six dogs. The animals were studied before and three to six months after surgical implantation of a thin polyester mesh (cardiac support device [CSD]) that surrounded both cardiac ventricles. Pressure-volume relations were measured by a conductance micromanometer catheter.

RESULTS

Long-term use of the CSD lowered end-diastolic and end-systolic volumes by -19 +/- 4% and -22 +/- 8%, respectively (both p < 0.0001) and shifted the end-systolic pressure-volume relation to the left (p < 0.01), compatible with reverse remodeling. End-diastolic pressure and chamber diastolic stiffness did not significantly change. The systolic response to dobutamine markedly improved after CSD implantation (55 +/- 8% rise in ejection fraction after CSD vs. -10 +/- 8% before CSD, p < 0.05), in conjunction with a heightened adenylyl cyclase response to isoproterenol. There was no change in the density or affinity of beta-adrenergic receptors. Diastolic compliance was not adversely affected, and preload-recruitable function was preserved with the CSD, consistent with a lack of constriction.

CONCLUSIONS

Reverse remodeling with reduced systolic wall stress and improved adrenergic signaling can be achieved by passive external support that does not generate diastolic constriction. This approach may prove useful in the treatment of chronic heart failure.

Proliferative signaling and disease progression in heart failure

Therapy for heart failure has traditionally been directed to such short-term functional abnormalities as low cardiac output, high filling pressures, and fluid retention. More recently, it has become clear that therapy must also inhibit the proliferative responses that contribute to the progressive deterioration of the failing heart. That heart failure is more than a hemodynamic disorder became apparent when clinical trials showed that drugs that improve such functional abnormalities as high venous pressure and low cardiac output failed to improve long-term prognosis. Most vasodilators, in spite of alleviating short-term problems caused by excessive afterload, increase long-term mortality; the notable exceptions are ACE inhibitors, the ability of which to prolong survival and inhibit remodeling can be attributed to inhibition of proliferative signaling. Other clinical trials showed that inotropic drugs, while providing immediate relief of symptoms, generally shorten long-term survival, whereas beta-adrenergic receptor blockers, which inhibit proliferative signaling by norepinephrine, improve prognosis. These findings can be explained by crossovers between functional and proliferative signaling, among the most important of which is the ability of neurohumoral mediators, such as norepinephrine and angiotensin II, to stimulate maladaptive hypertrophy, remodeling, apoptosis and other deleterious proliferative responses in the failing heart. The emerging understanding of the role of cytoskeletal and cell adhesion molecules in activating maladaptive proliferative responses suggests additional targets for therapy, and the rapid pace of discovery in molecular biology promises additional opportunities to inhibit this abnormal signaling, which causes progressive ventricular dilatation (remodeling) and cardiac cell death, now recognized to be major problems in this syndrome.

Beta-blockade in hypertension and congestive heart failure

Hypertension is common and increases the risk of death from coronary artery disease and cerebral vascular disease. The reason for treating hypertension is to prevent the long-term complications of this disorder. Many studies of antihypertensive therapy have produced only modest reductions in coronary events; in particular, with the use of beta-blockers. Clinical trials and meta-analyses have shown a lesser effect of these drugs on primary prevention of coronary events, cardiovascular and total mortality with respect to other antihypertensive approaches based on the use of low-dose diuretic therapy, especially in the elderly, even if the reduction of stroke and heart failure (HF) were similar. New beta-blockers with vasodilating properties due to the capacity to enhance the release of endothelial nitric oxide, then lessening a contributory mechanism to the pathogenesis of atherosclerosis as endothelial damage and dysfunction, seem to possess considerable potential in the treatment of hypertension, particularly in terms of improvement of cardiovascular outcome of patients. In HF, there is now considerable interest in the therapeutic use of beta-blockade. Some recent clinical trials have demonstrated conclusive evidence of the beneficial effects of beta-blocker therapy on survival in chronic HF. As a result of these data, beta-blocker therapy has become part of standard therapy for patients with chronic HF, in addition to angiotensin-converting enzyme-inhibitors and diuretics. The treatment is, in general, well tolerated. There are, however, some unanswered questions. One is whether some beta-blockers may be better than others. The major mortality benefit is probably a class-effect of beta1-adrenoceptor blockade, but the differences between beta-blockers might be clinically relevant. For example, it is under debate whether ancillary properties of some beta-blockers, such as the capability of exerting antioxidant effects or enhancing the nitric oxide production, may contribute to the clinical effects of these drugs. Future clinical trials will report over the next few years and help to answer the question about differences in mortality effects among types of beta-blocking agents, thus correctly defining the precise role of these drugs in the wide spectrum of cardiovascular disease.

Effect of early treatment with captopril and metoprolol singly and together on postinfarction left ventricular remodeling

BACKGROUND

beta-Blockers improve clinical outcome after acute myocardial infarction (AMI), but few data are available on their effectiveness in preventing left ventricular remodeling. The aim of the study was to assess the relative effects of captopril, metoprolol, and their combination on left ventricular remodeling after uncomplicated AMI.

METHODS

Two hundred fifty consecutive patients with a first AMI were randomly allocated to receive for 6 months captopril (up to 75 mg/d, group 1), metoprolol (up to 200 mg/d, group 2), or both (group 3) starting within 24 hours from symptom onset. Of these, 130 patients (group 1, 46; group 2, 47; group 3, 37) completed the study; all patients underwent 2-dimensional echocardiography at baseline and after 2 weeks and 3 and 6 months from AMI.

RESULTS

At 6 months, in comparison with baseline values, left ventricular end-diastolic area index (LVEDI) significantly increased in group 3 (P =.013) and wall motion score index significantly decreased in group 1 (P =.038). At any follow-up evaluation, the covariance analysis showed significantly greater interval changes in LVEDI in group 3 than in group 1 (P =.0077 at 2 weeks, P =.0108 at 3 months, and P = 0.0155 at 6 months). No significant differences were observed between group 1 and group 2 and between group 2 and group 3.

CONCLUSIONS

After uncomplicated first AMI, early and long-term treatment with captopril alone attenuates left ventricular remodeling better than its combination with metoprolol. In the head-to-head captopril versus metoprolol therapy strategy comparison, captopril alone seems more effective in reducing postinfarction enlargement, but a definite difference was not demonstrated.

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.

Carvedilol in the treatment of chronic heart failure

Along with the angiotensin-converting enzyme inhibitors (ACEIs), the beta-adrenergic receptor blockers have gradually emerged to be standard in the therapy of heart failure. Individual beta-blockers that have been shown to reduce all-cause mortality in patients with heart failure include bisoprolol, metoprolol and carvedilol. Carvedilol distinguishes from the other beta-blockers as being a non-selective beta(1)- and beta(2)-receptor blocker with (1)-receptor blockade effect and anti-oxidant properties. The drug does not have sympathomimetic activity and has vasodilatory effects attributable to its (1)-receptor blockade property. Experimental and clinical studies have confirmed carvedilol's vasodilator, anti-oxidant and anti-apoptotic properties, which may contribute to its effect in reversing cardiac remodelling in animal models and patients with heart failure. These pharmacological properties render carvedilol a potentially useful agent in the treatment of patients with heart failure. Early studies of carvedilol in heart failure have reported beneficial haemodynamic effects but variable effects on exercise tolerance and clinical well being. The large-scale US Carvedilol Heart Failure Program and the Australian/New Zealand Heart Failure Collaborative Research Group reported beneficial effects of carvedilol on mortality, morbidity and clinical well being in patients with mild-to-moderate heart failure. The recently reported but yet unpublished preliminary results of the COPERNICUS study suggest that carvedilol improves mortality and morbidity in patients with advanced heart failure and severe symptoms. At this time, it is unclear whether the ancillary pharmacological properties of carvedilol can be translated to more superior clinical benefit compared to the other beta-blockers. Preliminary studies examining surrogate end points suggest that carvedilol may improve left ventricular ejection fraction (LVEF) more than metoprolol. More conclusive information regarding their relative effects of clinical outcomes will await the completion of the COMET study, which compares the effect of metoprolol and carvedilol on mortality and morbidity, expected at the end of the year 2002.

Long-term effects of bisoprolol compared with imidapril on left ventricular remodeling after reperfusion in acute myocardial infarction: an angiographic study in patients with maintained vessel patency

BACKGROUND

Although angiotensin-converting enzyme inhibitor attenuates ventricular enlargement, whether beta-blocker therapy induces regression of left ventricular remodeling is not known. The purpose of this study was to compare the effects of bisoprolol therapy with those of imidapril therapy on left ventricular remodeling after acute myocardial infarction (AMI).

METHODS

Sixty patients with AMI who underwent reperfusion therapy were randomly assigned to an imidapril group (20 patients), a bisoprolol group (20 patients), or a control group (20 patients). Administration was started within 24 hours. Left ventricular function on admission and 3 months and 1 year after AMI was investigated.

RESULTS

Baseline characteristics on admission were similar in the 3 groups except for sex distribution. Mean pulmonary capillary wedge pressure and left ventricular end-diastolic pressure in the bisoprolol group were higher than those in the imidapril group 1 year after admission (pulmonary capillary wedge pressure: 12 +/- 7 vs 8 +/- 2 mm Hg, left ventricular end-diastolic pressure: 17 +/- 8 vs 11 +/- 4 mm Hg, P <. 01). Left ventricular end-diastolic volume index (EDVI) increased in the bisoprolol group throughout the 1-year period (P <.01), whereas EDVI in the imidapril group decreased (P <.01). The increases in EDVI during 1 year in the bisoprolol group were greater than those of the other 2 groups (bisoprolol: 12 +/- 10, imidapril: -9 +/- 7, control: 4 +/- 11 mL/m2, P <.01).

CONCLUSIONS

Early treatment with bisoprolol in AMI cannot prevent left ventricular remodeling, whereas imidapril attenuates left ventricular dilation by decreasing preload.

Influence of beta-blockers on mortality in chronic heart failure

OBJECTIVE

To briefly discuss the pathophysiology of heart failure and the rationale for the use of beta-blockers in the treatment of chronic heart failure. Key morbidity reduction trials are briefly mentioned, and recent mortality reduction trials are reviewed. General recommendations regarding the use of beta-blockers in heart failure are also included to guide clinical practice.

STUDY SELECTION/DATA EXTRACTION

Randomized, placebo-controlled clinical trials and meta-analyses evaluating mortality reduction with beta-blockers in the treatment of heart failure were identified using a MEDLINE search from January 1993 to March 2000. Abstracts and presented results from recent scientific meetings were also considered.

DATA SYNTHESIS

Beta-blockers have been shown to decrease hospitalization for worsening heart failure, decrease the need for heart transplant, improve New York Heart Association (NYHA) functional class, and increase left-ventricular ejection fraction. A mortality benefit has recently been demonstrated for patients with chronic heart failure. Carvedilol, bisoprolol, and controlled-release/extended-release metoprolol decreased the risk of dying by 65%, 34%, and 34%, respectively, in patients with primarily NYHA functional class II or III and systolic dysfunction. The benefit of these agents in patients with class IV heart failure or determining whether one agent has an advantage over another is being investigated in ongoing clinical trials.

CONCLUSIONS

Several beta-blockers have demonstrated mortality reduction in the treatment of patients with NYHA functional class II or III heart failure and systolic dysfunction. Beta-blockers should be considered in these patients when they are clinically stable and taking the current standard therapy of a diuretic plus an angiotensin-converting enzyme inhibitor or other vasodilator agent.

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.

Beta blockers with ACE inhibitors in mild heart failure

ACE inhibitors are standard therapy for treating both symptomatic and asymptomatic patients with left ventricular dysfunction. However, recent clinical trials have shown that beta blockers further reduce mortality in patients with symptomatic heart failure treated with ACE inhibitors. However, the evidence in support of adding beta blockers to ACE inhibitor therapy in patients with asymptomatic left ventricular dysfunction is less certain. The mechanisms by which ACE inhibitors and beta blockers may exert benefit in patients with heart failure are discussed, and studies assessing the association of beta blockade with outcome in patients with mild heart failure receiving ACE inhibitor therapy are reviewed. (c)2000 by CHF, Inc.

Left ventricular assist device as a bridge to patient and myocardial recovery

This article reviews the effects of chronic left ventricular assist device implantation on functional changes in patients with end-stage heart disease. Functional recovery can be measured by using response to exercise, quality-of-life surveys, improvements in noncardiac organ function, or changes in metabolic and neurohormonal levels. Recovery in intrinsic function of the heart can be assessed by changes in cardiac pump function or in baseline histological or biochemical abnormalities. Improvements in all of these areas have been found, although many reported studies are limited by a small sample size from selected subsets of patients rather than consecutive series.

Cardiac afferents and neurohormonal activation in congestive heart failure

Cardiac chambers have afferent connections to the brainstem and to the spinal cord. Vagal afferents mediate depressor responses and become activated by volume expansion, increased myocardial contractility and atrial natriuretic factor. Sympathetic afferents, on the contrary, are activated by metabolic mediators, myocardial ischemia and cardiac enlargement. These opposite behaviors may lead to activation or suppression of the sympathetic nervous system and of the renin-angiotensin-aldosterone system. As cardiac diseases progress, the heart dilates, plasma norepinephrine increases, atrial natriuretic factor is released and the renin-angiotensin-aldosterone system is suppressed to maintain water and sodium excretion. This dissociation of the neurohormonal profile of cardiac patients, may be explained by coactivation of sympathetic afferents, by cardiac dilatation, and of vagal afferents by atrial natriuretic factor. In more advanced stages, atrial natriuretic factor suppression of the renin-angiotensin-aldosterone system is overridden by overt sympathetic activation and sodium and water retention ensues. Digitalis, angiotensin-converting enzyme inhibitors and beta-blockers selectively decrease cardiac adrenergic drive. A common mechanism of action, to all three groups of drugs, would be attenuation of sympathetic afferents and partial normalization of vagal afferents. Consequently, heart size and cardiac afferents emerge as the key factors to understand the pathophysiology and treatment of the syndrome of congestive heart failure.

Beneficial effects of long-term treatment with enalapril on cardiac function and heart rate variability in patients with old myocardial infarction

BACKGROUND

The beneficial effects of the early use of angiotensin-converting enzyme inhibitors (ACEis) in patients with acute myocardial infarction (MI) are well documented. However, the effects of ACEis in patients with an old MI and preserved cardiac function have not yet been studied. We examined the effects of 12 months of enalapril treatment in patients with previous MI.

METHODS AND RESULTS

Thirteen patients with an old MI and no overt congestive heart failure (CHF), aged 70 +/- 2 years, were treated with enalapril for 12 months. We also included 13 age- and sex-matched control patients who had a similar clinical background but were not treated with enalapril. Holter electrocardiography and echocardiography were performed at entry and after 12 months of treatment. Heart rate variability, low- and high-frequency powers (LF and HF), and the ratio between LF and HF (LF/HF) were analyzed. Changes from baseline to 12 months in HF, LF/HF, left ventricular end-diastolic dimension (LVEDD), and end-systolic dimension (LVESD) were significantly different in the enalapril group (HF, 8.1 +/- 0.9 to 9.3 +/- 0.9 milliseconds: LF/HF, 1.65 +/- 0.11 to 1.53 +/- 0.16; LVEDD, 57.2 +/- 1.6 to 54.7 +/- 1.6 mm; LVESD, 40.0 +/- 2.4 to 36.3 +/- 1.9 mm) compared with the control group (HF, 8.9 +/- 0.9 to 8.5 +/- 0.7 milliseconds; LF/HF, 1.78 +/- 0.18 to 1.88 +/- 0.15; LVEDD, 52.3 +/- 2.5 to 55.9 +/- 2.2 mm; LVESD, 32.5 +/- 2.6 to 36.1 +/- 2.6 mm; P < .05). The delta change (delta) in LVESD between the end and the start of study correlated inversely with deltaHF (r = -0.56; P < .05) and positively with deltaLF/HF (r = 0.65; P < .01).

CONCLUSION

Our results suggest possible ongoing structural changes in patients with old MI even in the absence of overt CHF. Enalapril seemed to prevent such changes and to restore cardiac autonomic tone toward normal. Further prospective studies using a larger sample size are warranted to confirm potential beneficial effects of ACEis in patients with previous MI and preserved left ventricular function.

Beta-blockade improves adjacent regional sympathetic innervation during postinfarction remodeling

The effect of beta-blockade on left ventricular (LV) remodeling, when added to angiotensin-converting enzyme inhibition (ACEI) after anterior myocardial infarction (MI), is incompletely understood. On day 2 after coronary ligation-induced anteroapical infarction, 17 sheep were randomized to ramipril (ACEI, n = 8) or ramipril and metoprolol (ACEI-beta, n = 9). Magnetic resonance imaging was performed before and 8 wk after MI to measure changes in LV end-diastolic, end-systolic, and stroke volume indexes, LV mass index, ejection fraction (EF), and regional percent intramyocardial circumferential shortening. (123)I-labeled m-iodobenzylguanidine (MIBG) and fluorescent microspheres before and after adenosine were infused before death at 8 wk post-MI for quantitation of sympathetic innervation, blood flow, and blood flow reserve in adjacent and remote noninfarcted regions. Infarct size, regional blood flow, blood flow reserve, and the increase in LV mass and LV end-diastolic and end-systolic volume indexes were similar between groups. However, EF fell less over the 8-wk study period in the ACEI-beta group (-13 +/- 11 vs. -22 +/- 4% in ACEI, P < 0.05). The ratio of adjacent to remote region (123)I-MIBG uptake was greater in ACEI-beta animals than in the ACEI group (0.93 +/- 0.06 vs. 0.86 +/- 0.07, P < 0.04). When added to ACE inhibition after transmural anteroapical MI, beta-blockade improves EF and adjacent regional sympathetic innervation but does not alter LV size.

Large animal models of heart failure

Congestive heart failure (HF) is a major focus of medical research. Its incidence has greatly increased in recent decades because of an aging population base and the increasingly successful treatment of other forms of chronic cardiac disease. Relevant large animal models of HF should reflect the complex interactions of cardiac dysfunction, neurohumoral dynamics and peripheral vascular abnormalities found in human HF. A number of large animal models have been developed, especially in dogs, sheep and swine, using naturally occurring HF, or single or combinations of interventions, as instruments to trigger the development of HF. Naturally occurring HF models are not commonly used because of ethical or perceived ethical grounds, however, King Charles Cavalier Spaniel and Yucatan Mini Pig models have been described. Tachycardia induced HF is the most commonly used HF model. Ventricular pacing at 220-240 bpm results in profound low output, biventricular, oedematous failure in two to three weeks. Lower pacing rates result in a more stable, sustainable, lesser degree of failure. Positive features of this model include 'acceptance', aetiological relevance to patient tachycardia induced HF, neurohumoral and functional profile similar to most human HF, relatively low cost simple preparation, ability to manipulate the degree of failure with pacing rate, reversibility, reliability and a large amount of published multi species data. Limitations to the use of the model are the rapid onset, the fact that reversibility is only relevant to the tachycardia induced patient HF, the absence of hypertrophy in failure, the diminished plasma atrial natriuretic peptide (ANP) levels, absence of ANP of ventricular origin, and the interference between rapid pacing and therapeutic interventions. Myocardial damage models of HF include those models induced by ischaemia, eg due to coronary occlusion (ligation or aneroid) or intracoronary microembolism, transmyocardial DC shock, toxic cardiomyopathy from adriamycin, doxorubicin or catecholamines. Overload models of HF may be induced by high pressure from aortic constriction, aortic regurgitation, renal artery constriction, pulmonary stenosis or aortocaval shunts, or by induction of mitral regurgitation from chordae or leaflet damage. No single, all-encompassing, large animal model of HF exists to date. Selection of the type of model to be used should be based primarily on the hypotheses to be tested and secondarily on the available resources and facilities.

Medical and surgical therapy for cardiac remodeling

Ventricular remodeling refers to changes in ventricular geometry, volume, mass, and myocellular structure in response to myocardial injury or alteration in loading conditions. Although initially adaptive as a consequence of the initial damage to the myocardium, progressive ventricular remodeling is ultimately a maladaptive process that is associated with significant cardiovascular morbidity and mortality. Treatment with an aim to halt or reverse remodeling with mainly two classes of medications, angiotensin-converting enzyme inhibitors and beta-adrenergic blockers, has been shown to improve the long-term outcome. The role of pharmacologic and surgical therapy in remodeling is evolving and may have an important impact on the development of new directions of therapy for heart failure, myocardial infarction, and hypertension.

Beta-adrenergic blocking agent use and mortality in patients with asymptomatic and symptomatic left ventricular systolic dysfunction: a post hoc analysis of the Studies of Left Ventricular Dysfunction

OBJECTIVES

This analysis was performed to assess whether beta-adrenergic blocking agent use is associated with reduced mortality in the Studies of Left Ventricular Dysfunction (SOLVD) and to determine if this relationship is altered by angiotensin-converting enzyme (ACE) inhibitor use.

BACKGROUND

The ability of beta-blockers to alter mortality in patients with asymptomatic left ventricular dysfunction is not well defined. Furthermore, the effect of beta-blocker use, in addition to an ACE inhibitor, on these patients has not been fully addressed.

METHODS

This retrospective analysis evaluated the association of baseline beta-blocker use with mortality in 4,223 mostly asymptomatic Prevention trial patients, and 2,567 symptomatic Treatment trial patients.

RESULTS

The 1,015 (24%) Prevention trial patients and 197 (8%) Treatment trial patients receiving beta-blockers had fewer symptoms, higher ejection fractions and different use of medications than patients not receiving beta-blockers. On univariate analysis, beta-blocker use was associated with significantly lower mortality than nonuse in both trials. Moreover, a synergistic reduction in mortality with use of both a beta-blocker and enalapril was suggested in the Prevention trial. After adjusting for important prognostic variables with Cox multivariate analysis, the association of beta-adrenergic blocking agent use with reduced mortality remained significant for Prevention trial patients receiving enalapril. Lower rates of arrhythmic and pump failure death and risk of death or hospitalization for heart failure were observed.

CONCLUSIONS

The combination of a beta-blocker and enalapril was associated with a synergistic reduction in the risk of death in the SOLVD Prevention trial.

New method to evaluate myocyte remodeling from formalin-fixed biopsy and autopsy material

BACKGROUND

Excessive lengthening of cardiac myocytes attributed to series addition of sarcomeres is a consistent feature of left ventricular dilation in chronic heart failure. Currently, it is not feasible to assess myocyte dimensions, particularly myocyte length, in a manner that is of potential diagnostic usefulness.

METHODS AND RESULTS

Isolated myocytes from three groups of normal rats (100, 200, and 300 g) were obtained by using two different methods: (1) digestion of formalin-fixed myocardial tissue using potassium hydroxide (KOH) and (2) retrograde aortic perfusion of fresh hearts with collagenase. There was no difference in mean cell length between the two methods. The KOH method was also used to isolate intact, rod-shaped myocytes from formalin-fixed human cadaver left ventricles (control, n = 3; heart failure, n = 3) and from human right ventricle biopsy specimens (n = 6). Confirming our previous work using collagenase-isolated myocytes from fresh human explants, left ventricular myocytes from failing hearts showed longer mean cell length compared with control hearts. Data from human right ventricle biopsy specimens confirmed our previous finding in rats that myocyte lengthening is less pronounced in this chamber in heart failure.

CONCLUSIONS

The KOH method can be used to obtain reliable measurements of myocyte length and other cellular parameters from myocardial biopsies and autopsy material. Such data may be useful in the diagnostic assessment of remodeling associated with heart failure.

Evidence of phenotypic alteration as a cause of systolic dysfunction in the failing heart

This article describes the phenotype of dilated cardiomyopathy in humans and describes parallel studies in experimental models that support or refute the relevance of these changes to the development of the heart failure phenotype.

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

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

Neurohumoral activation and progression of heart failure: hypothetical and clinical considerations

The model for heart failure has changed radically over the past 20 years. No longer a simple hemodynamic paradigm of pump dysfunction, heart failure is now characterized as a complex clinical syndrome with release of many neurohormones and cytokines, which are believed to be most responsible for progression of disease. This change in our understanding of the pathophysiology of heart failure has important therapeutic implications. Drugs designed to influence the myocardial contractile state have been found over the past few decades to have either a neutral or an adverse effect on long-term survival, whereas agents designed to block the renin-angiotensin-aldosterone and other neurohormonal systems have proved to be remarkably effective treatment. Recently, drugs designed to block excessive sympathetic nervous system activity have been demonstrated in well-controlled studies to be safe and effective forms of therapy for heart failure. Carvedilol, a nonselective beta-adrenergic blocker with alpha1-blocking and antioxidant properties, is associated with prevention of progression of heart failure as manifested by improvement in left ventricular (LV) function, reduction in heart size, and improved survival in patients with New York Heart Association functional Class II and III symptoms. This improvement is observed equally in patients with ischemic and non-ischemic heart failure. It is tempting to speculate that beta-adrenergic blockers prevent the progression of heart failure by reducing LV mass and LV chamber size. In essence, carvedilol, and perhaps other beta-adrenergic blockers, appear to abrogate relentless LV remodeling which is typically associated with progression of heart failure. The combination of angiotensin-converting enzyme inhibitors and beta-adrenergic blockers may be particularly effective in this regard, although more data on beta-adrenergic blockers in patients with advanced heart failure are needed. Data from experimental heart failure animal models also suggest that endothelin (ET) subtype A (ET(A)) receptor blockers have the potential to lessen the pace of progressive LV remodeling. As our understanding of the neuroendocrine response to diminished cardiac performance improves, novel and even more imaginative neurohormonal and cytokine antagonists are likely to emerge as important new treatments for both hypertension and heart failure.

Growth hormone: a new therapy for heart failure?

There is now little doubt that growth hormone (GH) and insulin-like growth factor-1 (IGF-1) play a role in cardiac development and in cardiovascular physiology in adult life. Congenital lack of GH is associated with defective cardiac growth, ventricular wall thinning, and impaired systolic function. These abnormalities limit exercise capacity and contribute to the poor quality of life in patients with GH deficiency. In addition, studies with in vitro muscle preparations have shown that IGF-1 affects myocardial contractility by a direct mechanism. These findings suggested that GH would benefit patients affected by heart failure. Indeed, GH and/or IGF-1 have proven beneficial in various models of experimental heart failure. Tested in patients with classes II-IV heart failure, they improved cardiac performance and clinical status. These effects were associated with improved myocardial energetics and de-activation of the neurohormonal system. Because of the uncontrolled nature of the studies and the small number of cases examined, conclusions as to the effectiveness of GH and IGF-1 must await the results from larger trials.

Beta-adrenergic blockade in chronic heart failure: principles, progress, and practice

Prolonged activation of the sympathetic nervous system in patients with impaired ventricular function exerts adverse effects on the heart and circulation by a variety of mechanisms that are triggered by the interaction of norepinephrine and epinephrine with alpha1-, beta1-, and beta2-adrenergic receptors. Drugs that interfere with the actions of the sympathetic nervous system on alpha- and beta-receptors might be expected to antagonize these deleterious effects. beta1-receptor blockers have been shown to prevent and reverse many of the structural and functional changes that occur during the progression of heart failure, and beta2- and alpha1-receptor blockade seems to enhance the ability of beta1-blockers to prevent the toxic effects of catecholamines. In a large number of randomized, double-blind, placebo-controlled trials, long-term treatment of patients with chronic heart failure with beta-adrenergic blockers improves cardiac function, ameliorates symptoms, and reduces the risk of death and hospitalization. The nature and consistency of these benefits have led an increasing number of physicians to conclude that most patients with heart failure should be considered candidates for long-term treatment with these drugs. Analysis of these clinical trials has also raised the possibility that beta-blockers might differ from each other. Specifically, might agents that block alpha1-, betal-, and beta2-receptors be more effective and better tolerated that agents that act selectively on the beta1-receptor? This hypothesis is now being evaluated in a large-scale, long-term, international trial.

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

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

Overview of the treatment of heart failure

Short-term goals of heart failure management are directed toward relieving symptoms such as shortness of breath, decreased exercise tolerance, and lower-extremity edema and improving functional capacity and quality of life. Long-term goals include decreasing mortality and slowing or reversing the underlying cardiac structural abnormalities of heart failure. Improvement in symptomatic endpoints (e.g., exercise tolerance) does not necessarily correlate with endpoints for improved survival (e.g., left ventricular ejection fraction). It is therefore important to evaluate the effects of drugs on these distinct endpoints separately. Symptoms of heart failure are commonly managed with the use of diuretics, vasodilators, and positive inotropes or digoxin. Ideally, therapy should consist of a diuretic plus vasodilator (e.g., angiotensin-converting enzyme [ACE] inhibitor or isosorbide dinitrate plus hydralazine), with or without digoxin. Prevention of further left ventricular dysfunction can be accomplished by inhibiting neurohormonal processes and ventricular remodeling that occur in heart failure using ACE inhibitors, nitrates and hydralazine, or beta blockers. Significant therapeutic advances have been made with respect to symptom relief, hospitalizations, and mortality reduction in patients with congestive heart failure. Despite these advances, patient morbidity and mortality remain high and underscore the necessity for optimal use of existing therapies along with research directed at achieving further improvements in both quality of life and life expectancy.

Effects of beta-adrenergic blockade on survival of patients with chronic heart failure

Observations from experimental studies and controlled clinical trials indicate that prolonged activation of the sympathetic nervous system can accelerate the progression of heart failure, and that the risks of such progression can be substantially decreased through the use of pharmacologic agents that interfere with the actions of the sympathetic nervous system on the heart and peripheral blond vessels. Early studies with beta(1)-selective agents such as metoprolol and bisoprolol suggested that treatment with beta blockers could decrease the risk of worsening heart failure, but showed little or equivocal effects on survival. Recent studies using a more complex nonselective beta blocker (e.g., carvedilol) have reported a reduction in mortality as well as in the combined risk of death and hospitalization. This ability to decrease the risk of disease progression led to the recent approval of carvedilol for the treatment of chronic heart failure by the US Food and Drug Administration. However, it is not clear whether these survival effects represent a class effect of beta blockers or a specific effect of carvedilol. Carvedilol antagonizes several biologic mechanisms not blocked by metoprolol or bisoprolol that are thought to mediate the progression of heart failure. In addition, in 3 meta-analyses, the survival effects of nonselective vasodilating beta blockers appeared to be greater than those of beta(1)-selective nonvasodilating beta blockers. Moreover, it is unknown whether survival benefits can be expected only in the patients who were enrolled in the clinical trials (i.e., New York Heart Association class II or III patients) or whether they can also he achieved in patients with less severe or more severe symptoms (class I or IV heart failure). These questions are being addressed in several ongoing large-scale, long-term survival trials that are scheduled for completion within the next 5 years.

Effect of the calcium antagonist felodipine as supplementary vasodilator therapy in patients with chronic heart failure treated with enalapril: V-HeFT III. Vasodilator-Heart Failure Trial (V-HeFT) Study Group

BACKGROUND

Despite therapy with diuretics, ACE inhibitors and digoxin morbidity and mortality in heart failure remain high and might respond favorably to an additional vasodilator.

METHODS AND RESULTS

Male patients (n=450) with chronic heart failure (cardiac dysfunction and impaired exercise performance) on optimal current therapy (97% enalapril, 89% diuretics) were randomly assigned to double-blind treatment with felodipine extended release (5 mg BID) or placebo for 3 to 39 months (average, 18 months). Felodipine significantly reduced blood pressure and, at 3 months, increased ejection fraction (2.1% versus -0.1% units in the placebo group, P=.001) and reduced plasma atrial natriuretic peptide levels (-2.9 versus 26.9 pg/mL in the placebo group, P=.01) but did not improve exercise tolerance, quality of life, or the need for hospitalization. During long-term follow-up, the favorable effects on ejection fraction and atrial peptide did not persist, but felodipine prevented worsening exercise tolerance and quality of life. In the felodipine and placebo groups, mortality (13.8% versus 12.8%, respectively) and hospitalization (43% versus 42%) rates were similar, and a higher incidence of peripheral edema was the only apparent side effect of felodipine therapy.

CONCLUSIONS

Felodipine exerts a well-tolerated additional sustained vasodilator effect in patients with heart failure treated with enalapril, but the only possible long-term benefit was a trend for better exercise tolerance and less depression of quality of life in the second year of treatment. The drug appears to be safe but not clearly efficacious in patients with heart failure.