Current and novel pharmacologic approaches in advanced heart failure

Comparison of two doses and dosing regimens of tolvaptan in congestive heart failure

Fluid retention and extracellular volume expansion are frequently encountered complications of congestive heart failure (HF) that can cause morbidity and mortality. Tolvaptan (Otsuka) is an orally administered nonpeptide vasopressin (VP) V2 receptor antagonist that inhibits water reabsorption in the kidney by competitively blocking VP binding, resulting in water diuresis without significantly changing total electrolyte excretion. In the 24-hour period following a 30-mg dose of tolvaptan, urine excretion rate increases and declines as plasma concentrations rise and fall; this uneven effect results in 80% of daily urine output in the first 12 hours. Therefore, the current study was designed to assess the pharmacodynamic effects, pharmacokinetics, and clinical safety of tolvaptan 30 mg QD plus placebo versus 15 mg BID over 7 days in patients with NYHA Class II/III heart failure and persistent fluid overload, SBP > or = 90 mm Hg, and a serum creatinine < or = 3.0 mg/dL. Patients were withdrawn from diuretics for 48 hours before randomization. Statistics were performed with ANCOVA for continuous variables and Mantel-Haenszel mean score test stratified by center for categorical variables. Thirty-nine of 40 patients completed days 1 and 7. There were no significant clinical, pharmacokinetic, or pharmacodynamic differences between the dosing regimens over time. Based on these findings, tolvaptan 30 mg was chosen as the comparator for placebo in a large phase 3 survival trial.

Inotropic therapy for heart failure: an evidence-based approach

BACKGROUND

Agents that increase cardiac contractility (positive inotropes) have beneficial hemodynamic effects in patients with acute and chronic heart failure but have frequently led to increased mortality when given on a long-term basis. Despite this fact, inotropes remain commonly used in the management of heart failure.

METHODS

We reviewed the available data on short- and long-term inotrope use in heart failure, emphasizing high-quality evidence on the basis of randomized trials that were powered to address clinical end points.

RESULTS

Available data suggest that long-term inotropic therapy has a negative impact on survival in patients with heart failure, regardless of the agent used. The data that inotropic therapy improves quality of life are mixed. High-quality randomized evidence is lacking for the use of inotropes for other heart failure indications, such as for acute decompensations or as a "bridge to transplant."

CONCLUSIONS

On the basis of the available evidence, the routine use of inotropes as heart failure therapy is not indicated in either the acute or chronic setting. Potentially appropriate uses of inotropes include as temporary treatment of diuretic-refractory acute heart failure decompensations or as a bridge to definitive treatment such as revascularization or cardiac transplantation. Inotropes also may be appropriate as a palliative measure in patients with truly end-stage heart failure. A model of heart failure pathophysiologic features that combines an understanding of both hemodynamic and neurohormonal factors will be required to best develop and evaluate novel treatments for advanced heart failure.

Management of advanced heart failure

Congestive heart failure (CHF) due to progressive systolic dysfunction has become a modern-day epidemic. Despite the increased incidence and prevalence, significant progress has been made in the past 10 to 15 years in the treatment of CHF at all stages. The current outlook for patients with newly diagnosed, mild heart failure is encouraging. It should be noted, however, that most of the morbidity and health care expenditure is incurred by a minority of patients diagnosed with CHF who are in the advanced stages of their disease. The thrust of this article will be to provide practical advice beyond current guidelines on the management of advanced CHF.

Rational use of inotropic therapy in heart failure

Despite their theoretic appeal, agents that increase cardiac contractility (positive inotropes) have consistently been shown to increase mortality when given chronically to patients with heart failure. The routine use of inotropes as heart failure therapy in either the acute or the chronic setting is not supported by the available data. Some appropriate uses of inotropes are as temporary treatment of diuretic-refractory acute heart failure decompensations, or as a bridge to definitive treatment such as revascularization or cardiac transplantation. Although controversial, the use of inotropes as a palliative measure in the small subset of patients with truly end-stage heart failure may be appropriate. An understanding of the appropriate goals of therapy is important for both patients and physicians if rational decisions about the use of inotropes are to be made.

Different baseline sympathovagal balance and cardiac autonomic responsiveness in ischemic and non-ischemic congestive heart failure

BACKGROUND

A profound autonomic unbalance is present in heart failure: its correlation with the etiology of the disease has never been investigated.

AIMS

We characterized the sympatho-vagal balance and autonomic responsiveness of 42 patients (21 with ischemic heart failure, 21 with idiopathic dilated cardiomyopathy). Patients had comparable NYHA class, ejection fraction, exercise pVO(2), exercise ventilatory response, incidence of beta-blocking treatment. None showed periodic breathing or nocturnal arterial desaturation.

METHODS

Heart rate variability was assessed in the time and frequency domain during: (1) 10 min of quiet supine resting and free breathing; (2) 10 min of regular breathing at a frequency of 20 acts/min (=parasympathetic stimulus); and (3) 10 min of active standing (=sympathetic stimulus). The ratio of the low- to high-frequency components of each autospectrum obtained in the frequency domain (LF/HF) was used as an index of sympathovagal balance.

RESULTS

Patients with ischemic heart failure had a greater baseline sympathetic activation (higher LF/HF) than those with idiopathic dilated cardiomyopathy, maintaining some parasympathetic responsiveness as well (reduced LF/HF with regular breathing).

CONCLUSIONS

There is a distinct autonomic control according to the etiology of heart failure, a finding that may help understanding its pathophysiology, and could be useful in the clinical management of patients.

The AHF SCENE II Preceptorship Program: rationale and design of an educational program to optimize management of advanced heart failure

Advanced heart failure requires specialized treatment to improve symptoms, increase survival, and reverse or slow disease progression. The Advanced Heart Failure Shared Clinical Experiences Network, or AHF SCENE, was founded in 1995 to provide small groups of health care professionals with better advanced heart failure management strategies by sharing clinical experiences from centers treating large numbers of patients. The original AHF SCENE program has since been modified to provide health care professionals with more information on current strategies for advanced heart failure management and to better serve the educational needs of professionals who care for these patients. AHF SCENE II promotes new methods, programs, procedures, and pharmacologic interventions and also describes strategies for tracking and improving clinical and economic outcomes in the management of advanced heart failure. AHF SCENE II supports the understanding that rapid, aggressive medical management is essential and is more effective in the context of a well designed program that spans the continuum of care. (c)2000 by CHF, Inc.

Spironolactone in congestive heart failure

When a large multicenter research trial is abruptly terminated, it is usually a consequence of significant adverse events. In contrast, when the Randomized Aldactone Evaluation Study (RALES) mortality trial was discontinued 18 months early, it was because of the prominent salutary effect of spironolactone, added to standard multidrug therapy consisting of an angiotensin converting enzyme (ACE) inhibitor and loop diuretic (with or without digoxin), in reducing the incidence of death and hospitalization in patients with severe congestive heart failure (CHF). Therapies directed toward suppression of neurohormonal activation have contributed to significant reductions in morbidity and mortality. ACE inhibitors, in particular, have had the largest impact on adverse outcome measures in CHF. Yet despite combined therapy with an ACE inhibitor and loop diuretic, patients on these agents still have an unacceptably high incidence of progressive ventricular failure and death. In the years that followed its discovery in 1954, aldosterone was considered a target for therapy in CHF because of its role in sodium retention. It is now clear that chronic elevations in plasma aldosterone are responsible for many other adverse effects (Fig. 1), including enhanced potassium and magnesium excretion, myocardial fibrosis, inhibition of catecholamine reuptake, endothelial cell and baroreceptor dysfunction, and ventricular arrhythmias. Blockade of aldosterone action is a desirable pharmacologic approach to treating both the underlying pathophysiology of CHF and its clinical consequences. Spironolactone promotes magnesium and potassium retention, increases uptake of myocardial norepinephrine, attenuates formation of myocardial fibrosis, and decreases mortality associated with both progressive ventricular dysfunction and malignant ventricular arrhythmias. Despite the encouraging results seen in the recent RALES mortality trial, a diagnosis of CHF still carries 30% to 40% mortality at 2 years. We need to continue the trend of evaluating newer therapies directed at the pathophysiologic mechanisms of this syndrome, with a goal toward delaying and eventually reversing long-term consequences.

Pathophysiology of pediatric heart failure

Our understanding of the syndrome of heart failure has undergone several revisions, most importantly in the second half of the 20th century. New insights into the mechanisms of diseases offer new, challenging, controversial and sometimes counterintuitive forms of therapy. The development and progression of heart failure results from a complex interplay of hemodynamic and neurohormonal, cellular and genetic factors, rather than simply changes in cardiac function. It is because of this reason that our therapeutic focus can no longer be solely based on supply and demand models. Since the description of the pulsatile nature of the heart function and the flow of blood around a circuit by W. Harvey, numerous new paradigms have been put forward to explain the nature of heart failure. However, no single new model thus far proposed has been able to displace previous ones and successfully dictate therapy. It is the purpose of this manuscript to review the overall current understanding of the heart failure syndrome and how these new ideas may affect our therapeutic approach.

Overview of the management of pediatric heart failure

For the most part of this the century heart failure syndrome was understood as a pump failure disorder with hemodynamic consequences stemming from the same myocardial dysfunction. In addition supply and demand theories were used to explain the nature of symptoms. As a result, therapeutic strategies were directed at correcting the abnormal hemodynamic conditions and normalizing the delivery of the much needed nutrients. Improvement of cardiac pump function with inotropic drugs and abnormal circulatory conditions with afterload and preload modifications became therapeutic goals and standards of care. However, while vasodilators and inotropic drugs immediately improved symptoms, hemodynamics and functional status, in the long term they either did not affect or worsen the natural history of heart failure. In pediatrics, this is further complicated by the lack of large scale trials addressing issues pertinent to the particularities that affect heart failure in children. In the late 1980s and 1990s heart failure has evolved into a more complex, multiple and interactive pathophysiologic disorder. Today not only the abnormal hemodynamics but also the biological disorders are pharmacologic targets. The reversal or slowing of myocardial maladaptation has become one of the most important therapeutic goals. With this end in mind therapeutic strategies may seem counterintuitive and paradoxical, such as the use of beta-blockers. This review will address the current thinking and therapeutic modalities used today in the treatment of heart failure syndrome in the adult population. We also discuss some of the issues why we think that these principles can be extrapolated to the pediatric population.

Cellular events linked to cardiac remodeling in heart failure: targets for pharmacologic intervention

Over the past decade, there has been a paradigm shift in the understanding of heart failure pathophysiology. Heart failure is no longer conceptualized as a hemodynamic disorder resulting from changes in renal and hormonal function. Rather, the syndrome of heart failure is more complex and is characterized by abnormal myocyte growth, proliferation of cells in the extracellular matrix, and myocyte cell loss (apoptosis)--all of which culminate in significant structural remodeling of the heart and loss of ventricular function. The loss of ventricle function is preceded by an initiating event such as myocardial infarction, which leads to changes in cell function, activation of specific neurohormones and peptides, which in turn are linked to the remodeling of the ventricle, and progression of heart failure. This article discusses how changes in myocyte and nonmyocyte structure may contribute to the progression of heart failure. Insight into these mechanisms will provide a better understanding of newer pharmacologic approaches in the treatment of heart failure.