Untreated heart failure: clinical and neuroendocrine effects of introducing diuretics

The benefit of low-dose dopamine during vigorous diuresis for congestive heart failure associated with renal insufficiency: does it protect renal function?

BACKGROUND

Low-dose dopamine, a renal vasodilator, has been used empirically to improve renal function or outcome in critically ill patients with oliguria or acute renal failure.

HYPOTHESIS

This study was designed to investigate the efficacy of low-dose dopamine (2 micrograms/kg/min) as a renal-protective agent during vigorous diuresis for congestive heart failure (CHF) associated with mild or moderate renal insufficiency.

METHODS

Of 20 study patients (mean age 74.3 +/- 15 years) with severe CHF, 10 (Group A) were randomized to a treatment strategy of intravenous bumetanide (1 mg b.i.d.) alone and another 10 (Group B) to low-dose dopamine and a similar diuretic regimen for a duration of 5 days or less if clinical edema remitted.

RESULTS

Group B patients showed a significant improvement in renal function and urinary output: serum blood urea nitrogen 48.9 +/- 10.3 to 32.1 +/- 14.4 mg/dl (p < 0.05); serum creatinine 1.97 +/- 0.24 to 1.49 +/- 0.39 mg/dl (p < 0.05); creatinine clearance 35.6 +/- 11.6 to 48.8 +/- 12.3 ml/min (p < 0.05); and indexed urinary output 0.56 +/- 0.16 to 2.02 +/- 0.72 ml/kg/h (p < 0.05). Group A patients showed a significant increase in urinary output but nonsignificant renal functional deterioration.

CONCLUSION

The renal-protective effect of low-dose dopamine in the setting of CHF and vigorous diuresis is supported by this study.

A Review of Critical Differences among Loop, Thiazide, and Thiazide-Like Diuretics

Diuretics are a drug class with heterogeneous assortments. This article reviews general pharmacologic mechanisms and clinical implications of loop, thiazide, and thiazide-like diuretics.

Loop diuretics act in the loop of Henle by blocking the sodium-potassium-chloride (Na+-K+-2Cl-) symport. They are effective in relieving congestive symptoms and edematous signs of heart failure. Activation of the neurohormonal system and subsequent pathologic myocardial remodeling limit the use of loop diuretics unless fluid balance is not met to relieve patients' symptoms with life-saving pharmacologic modalities. Adverse effects on electrolyte balance may cause life-threatening consequences. The combination of K+-sparing diuretics or angiotensin-converting enzyme inhibitors with loop diuretics may not only prevent life-threatening complications caused by electrolyte imbalance, but also may delay progression of the disease with proven mortality benefit. Recent findings of worsening renal function and higher mortality rate with the use of oral and intravenous loop diuretics further demands appropriate use of these drugs.

Thiazide diuretics and thiazide-like diuretics act in the distal convoluted tubule by blocking Na+-Cl- symport. Thiazide diuretics reduce cardiovascular mortality by achieving target blood pressure in patients with hypertension. Compared with other antihypertensive drugs, thiazide diuretics have less desirable metabolic effects. However, it has not yet been shown that the negative metabolic effects of these drugs are associated with negative mortality and morbidity. Based on the need for a multidrug regimen to reach target blood pressure in most patients with hypertension, thiazide diuretics may be used in addition to a drug or drugs without metabolic complications.

Tolvaptan: the evidence for its therapeutic value in acute heart failure syndrome

INTRODUCTION

Acute heart failure syndrome (AHFS) is one of the leading causes of hospital admission in the US. Tolvaptan is a vasopressin V(2) receptor antagonist that blocks the effect of arginine vasopressin (AVP) in reabsorbing water from the collecting ducts of the nephrons in congestive heart failure.

AIMS

To review the evidence for utilizing tolvaptan in the treatment of AHFS.

EVIDENCE REVIEW

Several clinical trials have sought to assess the clinical effects of tolvaptan in heart failure. Compared with placebo, tolvaptan has been shown to reduce bodyweight and improve serum sodium in patients with AHFS without worsening renal function. Tolvaptan appeared to be well tolerated with a good safety profile. It caused a significant reduction in pulmonary capillary wedge pressure compared with placebo, but has yet to demonstrate reversal of cardiac remodeling. A large-scale mortality trial showed no differences in long-term mortality rates between tolvaptan and placebo, although early symptom relief was apparent with tolvaptan and lower diuretic use.

PLACE IN THERAPY

Tolvaptan has shown to be safe and effective in treating congestion in AHFS. Free water excretion in fluid-overloaded patients vulnerable to cardiorenal compromise with standard diuretic therapy makes V(2) vasopressin receptor blockade an attractive adjunct to standard medical therapy aimed at reducing congestion in AHFS.

Pharmacokinetic and pharmacodynamic interaction between tolvaptan, a non-peptide AVP antagonist, and furosemide or hydrochlorothiazide

The pharmacokinetic and pharmacodynamic interactions between tolvaptan and furosemide or hydrochlorothiazide (HCTZ) were determined in a single-center, randomized, open-label, parallel-arm, 3-period crossover study conducted in healthy white (Caucasian) men. A total of 12 subjects were enrolled in the study, with 6 subjects assigned to each of two treatment arms. Subjects in Arm 1 received 30 mg of tolvaptan, 80 mg of furosemide, and 30 mg of tolvaptan + 80 mg of furosemide. Subjects in Arm 2 received 30 mg of tolvaptan, 100 mg of HCTZ, and 30 mg pf tolvaptan + 100 mg of HCTZ. Doses were separated by a 48-hour washout. Blood and urine samples were collected at scheduled timepoints during the 24 hours after administration of study drug for the determination of pharmacokinetic and pharmacodynamic parameters. No clinically significant changes were noted in the pharmacokinetic profiles of tolvaptan and furosemide or tolvaptan and HCTZ when coadministered. Free water clearance, 24-hour urine volume, plasma sodium and argentine vasopressin concentrations, and plasma osmolality were higher, and urine osmolality was lower when tolvaptan was administered either alone or in combination with furosemide or HCTZ, compared with furosemide or HCTZ administered alone. At 24 hours postdose, plasma renin activity was increased after furosemide or HCTZ administered alone or with tolvaptan, but it was unchanged after tolvaptan alone. Tolvaptan did not significantly affect the natriuretic activity of furosemide or HCTZ. Furosemide and HCTZ did not significantly affect the aquaretic activity of tolvaptan. Tolvaptan administered alone or in combination with furosemide or HCTZ was safe and well tolerated at the given doses.

A propensity-matched study of the effects of chronic diuretic therapy on mortality and hospitalization in older adults with heart failure

BACKGROUND

Non-potassium-sparing diuretics may increase mortality and hospitalizations in heart failure patients. Most heart failure patients are older adults, yet the effect of diuretics on cause-specific mortality and hospitalizations in older adults with heart failure is unknown. The objective of this propensity-matched study was to determine the effect of diuretics on mortality and hospitalizations in heart failure patients >or=65 years.

METHODS

Of the 7788 Digitalis Investigation Group participants, 4036 were >or=65 years and 3271 (81%) were receiving diuretics. Propensity scores for diuretic use for each of the 4036 patients were calculated using a non-parsimonious multivariable logistic regression model incorporating all measured baseline covariates, and were used to match 651 (85%) patients not receiving diuretics with 651 patients receiving diuretics. Effects of diuretics on mortality and hospitalization at 37 months of median follow-up were assessed using matched Cox regression models.

RESULTS

All-cause mortality occurred in 173 patients not receiving diuretics and 208 patients receiving diuretics respectively during 2056 and 1943 person-years of follow-up (hazard ratio {HR}=1.36; 95% confidence interval {CI}=1.08-1.71; p=0.009). All-cause hospitalizations occurred in 413 patients not receiving and 438 patients receiving diuretics respectively during 1255 and 1144 person-years of follow-up (HR=1.18; 95% CI=0.99-1.39; p=0.063). Diuretic use was associated with significant increased risk of cardiovascular mortality (HR=1.50; 95% CI=1.15-1.96; p=0.003).and heart failure hospitalization (HR=1.48; 95% CI=1.13-1.94; p=0.005).

CONCLUSIONS

Chronic diuretic use was associated with significant increased mortality and hospitalization in ambulatory older adults with heart failure receiving angiotensin converting enzyme inhibitor and diuretics.

[Drug treatment of chronic heart failure]

Drug treatment of chronic heart failure is undergoing continuous modifications according to the data of new trials. Treatment has to be adjusted to current guidelines. The state of the art of medical treatment of chronic heart failure is addressed in this report.

Optimal use of diuretics in patients with heart failure

Currently, the use of diuretics in heart failure (HF) remains more of an art than a science. Diuretics are the principle means for relieving congestion in patients with decompensated HF. Unfortunately, they persist as the only major therapy in HF that has not been subjected to a large randomized clinical trial, precisely because no comparable therapy exists that can so easily, efficiently, and inexpensively treat fluid overload. Nonetheless, diuretics have many potential drawbacks, including electrolyte abnormalities, neurohormonal activation, hypovolemia, renal dysfunction, and direct myocardial effects. Until definitive answers about mortality are settled, the lowest dose of a diuretic that can produce euvolemia should be employed and these agents should be discontinued when possible. Many outpatients with HF can be managed quite well without diuretics once adequate neurohormonal blockade with angiotensin-converting enzyme inhibitors and beta blockers has been achieved.

Novel strategies: challenge loop diuretics and sodium management in heart failure--Part I

This is the first of a 2-part series. This article reviews the relationships among diuretics, neurohormonal activation, renal function, fluid and Na management, the cardiorenal syndrome, and heart failure. Part II will describe novel therapies based on these relationships, focusing particularly on vasopressin antagonists and treatment using hypertonic saline solution with high-dose loop diuretics. Heart failure (HF) is a complex hemodynamic disorder characterized by chronic and progressive pump failure and fluid accumulation. Diuretics are a vital component of symptomatic management, and enhancing diuretic response in the setting of diuretic resistance is therefore pivotal. In HF patients treated with diuretics, compensatory pathophysiologic mechanisms to maintain vascular resistance, such as nonosmotic stimulation of vasopressin secretion and activation of the renin-angiotensin-aldosterone system and sympathetic nervous system, promote renal Na and water reabsorption. Thus, there remains a need to develop novel therapies for HF patients who are refractory to conventional medical treatment. The conflicting results of diuretic treatments in HF and the importance of Na management in the context of the cardiorenal syndrome and neurohormonal activation have suggested novel and counterintuitive strategies, focusing primarily on the use of vasopressin antagonists and hypertonic saline solution with high doses of loop diuretics and neurohormonal interference. The authors review the current evidence for these therapies and suggest hypothetical bases for their efficacy.

Why does chronic heart failure cause breathlessness and fatigue?

Traditional explanations for the symptoms of fatigue and breathlessness experienced by patients with chronic heart failure (CHF) focus on how reduced cardiac output on exercise leads to impaired skeletal muscle blood supply, thus causing fatigue, and on how the requirement for a raised left ventricular filling pressure to maintain cardiac output results in reduced pulmonary diffusion owing to interstitial edema, thus causing breathlessness. However, indices of left ventricular function relate poorly to exercise capacity and symptoms, suggesting that the origin of symptoms may lie elsewhere. There is a specific heart failure myopathy that is present early in the condition which may contribute largely to the sensation of fatigue. Receptors present in skeletal muscle sensitive to work (ergoreceptors) are overactive in patients with CHF, presumably as a consequence of the myopathy, and their activity is related both to the ventilatory response to exercise and breathlessness, and to the sympathetic overactivity of CHF. In the present paper, we review the systemic consequences of left ventricular dysfunction to understand how they relate to the symptoms of heart failure.

Pharmacological treatment of chronic heart failure

Heart failure (HF) is associated with a high morbidity and mortality in the Western World. Our knowledge of the epidemiology, pathophysiology, and therapy has improved dramatically during the last 20 years. Pharmacological treatment, as it stands today, is a combination of preventive and symptomatic strategies. The mainstay life-saving drugs are angiotensin-converting enzyme inhibitors and beta-blockers. Additional benefits are obtained when angiotensin-receptor blockers or aldosterone antagonists are added. Digitalis and/or diuretics are useful for symptom reduction. In addition, combination therapy with hydralazine and isosorbide dinitrate is recommended in African Americans.

Practical applications of intravenous diuretic therapy in decompensated heart failure

Intravenous (IV) loop diuretics play an important role in the treatment of decompensated heart failure (DHF). They inhibit the Na(+)-K(+)-2Cl(-) reabsorptive pump in the thick ascending limb of the loop of Henle, and the resultant natriuresis and diuresis decreases volume load, improves hemodynamics, and reduces DHF symptoms. However, loop diuretics have a short half-life and their efficacy may be limited by postdiuretic sodium rebound during the period between doses in which the tubular diuretic concentration is subtherapeutic. Moreover, they can produce electrolyte abnormalities, neurohormonal activation, intravascular volume depletion, and renal dysfunction. Several studies have reported an association between diuretic therapy and increased morbidity and mortality. In addition, many patients, especially those with more advanced forms of heart failure (HF), are resistant to standard doses of loop diuretics. These high-risk, resistant patients may benefit from pharmacologic and/or nonpharmacologic interventions to improve hemodynamic performance, treatment of renovascular disease, discontinuation of aspirin and other sodium-retaining drugs, manipulation of the route of delivery or combination of diuretic classes, or hemofiltration. Despite >50 years of use, many questions regarding the use of intravenous diuretic agents in patients with DHF are still unanswered, and there remains a compelling need for well-designed randomized, controlled clinical trials to establish appropriate treatment regimens that maximize therapeutic benefit while minimizing morbidity and mortality.

Beyond diuretics: management of volume overload in acute heart failure syndromes

Diuretics are an established foundation of therapy for patients with chronic heart failure (HF) as well as for those hospitalized for treatment of acute HF syndromes. Despite the accepted use of diuretics in acute HF syndromes, treatment patterns with diuretics vary widely, and there are no data from randomized studies on the benefit of diuretics on morbidity or mortality in patients hospitalized with acute HF syndromes. Additional pharmacologic therapies that complement or replace diuretics in this setting, especially in patients with diuretic resistance, include positive inotropes, nitrovasodilators, and natriuretic peptides, but data are likewise lacking on important clinical outcomes. Ultrafiltration has also been used as a nonpharmacologic strategy to treat patients with acute HF syndromes who exhibit resistance to diuretics. Effective monitoring of volume status with newer modalities may allow more selective use of diuretics and diuretic-like modalities, but additional randomized trial data are clearly needed to establish ideal strategies to promote volume removal in acute HF syndromes.

Emerging therapies for the management of decompensated heart failure: from bench to bedside

While pharmaceutical innovation has been highly successful in reducing mortality in chronic heart failure, this has not been matched by similar success in decompensated heart failure syndromes. Despite outstanding issues over definitions and end points, we argue in this paper that an unprecedented wealth of pharmacologic innovation may soon transform the management of these challenging patients. Agents that target contractility, such as cardiac myosin activators and novel adenosine triphosphate-dependent transmembrane sodium-potassium pump inhibitors, provide inotropic support without arrhythmogenic increases in cytosolic calcium or side effects of more traditional agents. Adenosine receptor blockade may improve glomerular filtration and diuresis by exerting a direct beneficial effect on glomerular blood flow while vasopressin antagonists promote free water excretion without compromising renal function and may simultaneously inhibit myocardial remodeling. Urodilatin, the renally synthesized isoform of atrial natriuretic peptide, may improve pulmonary congestion via vasodilation and enhanced diuresis. Finally, metabolic modulators such as perhexiline may optimize myocardial energy utilization by shifting adenosine triphosphate production from free fatty acids to glucose, a unique and conceptually appealing approach to the management of heart failure. These advances allow optimism not only for the advancement of our understanding and management of decompensated heart failure syndromes but for the translational research effort in heart failure biology in general.

Nesiritide: Harmful or Harmless?

Nesiritide is the recombinant form of human B-type (brain) natriuretic peptide (BNP), and its amino acid sequence is identical to that of endogenous human BNP. Administration of nesiritide results in venous and arterial vasodilation, as well as enhanced diuresis. Given the many limitations of therapies previously available for the treatment of acute decompensated heart failure, the anticipation was that nesiritide would offer a safer and more effective therapeutic option. Recently, two meta-analyses raised the question of safety with nesiritide therapy, specifically an increased risk of renal dysfunction and mortality. Although several studies generated information regarding the potential role of nesiritide in various settings, the questions raised by the meta-analyses are concerning. Our hope is that future clinical trials will address the concerns raised and provide a better understanding of the role of nesiritide in the management of acute decompensated heart failure. Until these data are available, nesiritide use should be limited.

Diuretic use, progressive heart failure, and death in patients in the DIG study

BACKGROUND

Nonpotassium-sparing diuretics (NPSDs), have been associated with increased sudden cardiac death (SCD) and progressive heart failure (HF) death in HF patients.

METHODS AND RESULTS

In 6797 Digitalis Investigation Group study patients, risk ratios were calculated for death, cardiovascular death (CVD), death from worsening HF, SCD, and HF hospitalization among those taking a potassium-sparing (PSD), NPSD, or no diuretic. Compared with not taking diuretic, risk of death (relative risk [RR] 1.36, 95% confidence interval [CI] 1.17-1.59, P < .0001), CVD (RR = 1.38, 95% CI 1.17-1.63, P = .0001), progressive HF death (RR = 1.41, 95% CI 1.06-1.89, P = .02), SCD (RR = 1.67, 95% CI 1.23-2.27, P = .001), and HF hospitalization (RR = 1.68, 95% CI 1.41-1.99, P < .0001) were increased with NPSD. There was no significant difference in any end point for patients taking only PSD compared to no diuretic. PSD only subjects were less likely than NPSD subjects to be hospitalized for HF (RR = 0.71, 95% CI 0.52-0.96, P = .02).

CONCLUSION

NPSDs are associated with increased risk of death, CVD, progressive HF death, SCD, and HF hospitalization. A randomized trial is needed to assess the role of NPSDs versus PSDs in HF patients.

Relation of loop diuretic dose to mortality in advanced heart failure

Although loop diuretics are widely used in heart failure (HF), their effect on outcomes has not been evaluated in large clinical trials. This study sought to determine the dose-dependent relation between loop diuretic use and HF prognosis. A cohort of 1,354 patients with advanced systolic HF referred to a single center was studied. Patients were divided into quartiles of equivalent total daily loop diuretic dose: 0 to 40, 41 to 80, 81 to 160, and >160 mg. The cohort was 76% male, with a mean age of 53+/-13 years and a mean ejection fraction of 24+/-7%. The mean diuretic dose equivalence was 107+/-87 mg. The diuretic quartile groups were similar in terms of gender, body mass index, ischemic cause of HF, history of hypertension, and spironolactone use, but the highest quartile was associated with a smaller ejection fraction and lower serum sodium and hemoglobin levels but higher serum blood urea nitrogen and creatinine levels. There was a decrease in survival with increasing diuretic dose (83%, 81%, 68%, and 53% for quartiles 1, 2, 3, and 4, respectively). Even after extensive co-variate adjustment (age, gender, ischemic cause of HF, the ejection fraction, body mass index, pulmonary capillary wedge pressure, peak oxygen consumption, beta-blocker use, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker use, digoxin use, statin use, serum sodium, blood urea nitrogen, creatinine, hemoglobin, cholesterol, systolic blood pressure, and smoking history), diuretic quartile remained an independent predictor of mortality (quartile 4 vs quartile 1 hazard ratio 4.0, 95% confidence interval 1.9 to 8.4). In conclusion, in this cohort of patients with advanced HF, there was an independent, dose-dependent association between loop diuretic use and impaired survival. Higher loop diuretic dosages identify patients with HF at particularly high risk for mortality.

Heart failure, chronic diuretic use, and increase in mortality and hospitalization: an observational study using propensity score methods

AIMS

Non-potassium-sparing diuretics are commonly used in heart failure (HF). They activate the neurohormonal system, and are potentially harmful. Yet, the long-term effects of chronic diuretic use in HF are largely unknown. We retrospectively analysed the Digitalis Investigation Group (DIG) data to determine the effects of diuretics on HF outcomes.

METHODS AND RESULTS

Propensity scores for diuretic use were calculated for each of the 7788 DIG participants using a non-parsimonious multivariable logistic regression model, and were used to match 1391 (81%) no-diuretic patients with 1391 diuretic patients. Effects of diuretics on mortality and hospitalization at 40 months of median follow-up were assessed using matched Cox regression models. All-cause mortality was 21% for no-diuretic patients and 29% for diuretic patients [hazard ratio (HR) 1.31; 95% confidence interval (CI) 1.11-1.55; P = 0.002]. HF hospitalizations occurred in 18% of no-diuretic patients and 23% of diuretic patients (HR 1.37; 95% CI 1.13-1.65; P = 0.001).

CONCLUSION

Chronic diuretic use was associated with increased long-term mortality and hospitalizations in a wide spectrum of ambulatory chronic systolic and diastolic HF patients. The findings of the current study challenge the wisdom of routine chronic use of diuretics in HF patients who are asymptomatic or minimally symptomatic without fluid retention, and are on complete neurohormonal blockade. These findings, based on a non-randomized design, need to be further studied in randomized trials.

Treating hyponatremia in heart failure

Hyponatremia is common and associated with adverse outcomes in patients with congestive heart failure (CHF). In many patients who have CHF with hyponatremia, plasma arginine vasopressin (AVP) is elevated inappropriately. AVP causes water retention by interacting with V2 receptors in the renal collecting duct, leading to dilutional hyponatremia and increased ventricular preload. AVP also may contribute to pathophysiologic process in CHF by interacting with V(IA) receptors on vascular smooth muscle cells and myocytes. The potential utility of AVP antagonists--V2 antagonists and dual V(IA)/V2 antagonists--in correcting hyponatremia and relieving the congestion and edema associated with CHF is being actively explored. Combined antagonists may offer additional benefit by interfering with excessive V(IA) signaling. Unlike diuretics, which increase urine volume and electrolyte excretion, AVP antagonists of these types produce an aquaresis characterized by an increase in free water clearance concomitant with sparing of electrolytes. Studies in experimental CHF as well as preliminary clinical trials with selective and nonselective V2 antagonists have been encouraging, suggesting that these agents may hold promise for treatment of hyponatremia in CHF.

Tolvaptan: a selective vasopressin type 2 receptor antagonist in congestive heart failure

The neurohormone arginine vasopressin plays a significant role in the regulation of volume homeostasis, which is mediated via vasopressin type 2 (V2) receptors in the collecting tubules of the kidney. Diseases that are accompanied by abnormal volume homeostasis, including congestive heart failure and cirrhosis, are a frequent cause of hospital admissions and increasing healthcare costs. Recently, several nonpeptide V2 receptor antagonists have emerged as promising agents in the management of these conditions with the advantage of having no electrolyte abnormalities, neurohormonal activation or worsening renal insufficiency. Tolvaptan, a highly selective nonpeptide V2 receptor antagonist, has demonstrated an improvement in the volume status, osmotic balance and haemodynamic profile in preclinical and Phase II trials in patients with congestive heart failure and is currently undergoing testing in Phase III trials. This review discusses the evidence for the potential uses of tolvaptan, and its pharmacology and pharmacokinetics, particularly in congestive 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.

Ultrafiltration in decompensated heart failure

Fluid congestion is the hallmark of decompensated heart failure. As heart failure progresses, reduced response to diuretics is common. In these patients, ultrafiltration has been found to alleviate excess volume and improve diuretic sensitivity. Compared with diuretics, ultrafiltration provides a more predictable and safer way to achieve euvolemia with minimal electrolyte abnormalities and neurohormonal activation. The emerging familiarity and ease of use of ultrafiltration suggests that in the future this will be an important therapy for the treatment of acute and chronic volume overload associated with decompensated heart failure.

Diuretics for heart failure

BACKGROUND

Chronic heart failure is a major cause of morbidity and mortality world-wide. Diuretics are regarded as the first-line treatment for patients with congestive heart failure since they provide symptomatic relief. The effects of diuretics on disease progression and survival remain unclear.

OBJECTIVES

To assess the harms and benefits of diuretics for chronic heart failure

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (Issue 2 2004), MEDLINE 1966-2004, EMBASE 1980-2004 and HERDIN database. We hand searched pertinent journals and reference lists of papers were inspected. We also contacted manufacturers and researchers in the field.

SELECTION CRITERIA

Only double-blinded randomised controlled trials of diuretic therapy comparing one diuretic with placebo, or one diuretic with another active agent (e.g. ACE inhibitors, digoxin) in patients with chronic heart failure were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two reviewers independently abstracted the data and assessed the eligibility and methodological quality of each trial. Extracted data were entered into the Review Manager 4.2 computer software, and analysed by determining the odds ratio for dichotomous data, and difference in means for continuous data, of the treated group compared with controls. The likelihood of heterogeneity of the study population was assessed by the Chi-square test. If there was no evidence of statistical heterogeneity and pooling of results was clinically appropriate, a combined estimate was obtained using the fixed-effects model.

MAIN RESULTS

We included 14 trials (525 participants), 7 were placebo-controlled, and 7 compared diuretics against other agents such as ACE inhibitors or digoxin. We analysed the data for mortality and for worsening heart failure. Mortality data were available in 3 of the placebo-controlled trials (202 participants). Mortality was lower for participants treated with diuretics than for placebo, odds ratio (OR) for death 0.24, 95% confidence interval (CI) 0.07 to 0.83; P = 0.02. Admission for worsening heart failure was reduced in those taking diuretics in two trials (169 participants), OR 0.07 (95% CI 0.01 to 0.52; P = 0.01). In four trials comparing diuretics to active control (91 participants), diuretics improved exercise capacity in participants with CHF, difference in means WMD 0.72 , 95% CI 0.40 to 1.04; P < 0.0001.

AUTHORS' CONCLUSIONS

The available data from several small trials show that in patients with chronic heart failure, conventional diuretics appear to reduce the risk of death and worsening heart failure compared to placebo. Compared to active control, diuretics appear to improve exercise capacity.

Observation unit treatment of heart failure with nesiritide: results from the proaction trial

This was a multicenter, randomized, double-blind, placebo-controlled pilot study, evaluating the safety and efficacy of a standard care treatment regimen with the addition of either nesiritide or placebo (SCP) in 237 Emergency Department (ED)/Observation Unit (OU) patients with decompensated heart failure (HF). Efficacy measures included initial admission, length of hospital stay (LOS), and inpatient rehospitalization through 30 days. Compared to the standard care group, patients who also received nesiritide had 11% fewer inpatient hospital admissions at the index ED visit (55% SCP, 49% nesiritide, p = 0.436), and 57% fewer inpatient hospitalizations within 30 days after discharge from the index hospitalization (23% SCP, 10% nesiritide, p = 0.058). The duration of rehospitalization was shorter for nesiritide patients (median LOS 2.5 vs. 6.5 days, p = 0.032). The incidence of symptomatic hypotension was low and did not differ between the groups. This study showed that nesiritide is safe when used in the emergency department, observation units, or similar settings.

Future options for management of heart failure in an emergency department observation unit

In the next year there will be over 1 million United States hospitalizations for acute decompensated heart failure (ADHF), with 80% admitted to the hospital through the emergency department. The short stay Observation Unit represents a new strategy for diagnosis and treatment of ADHF. This manuscript examines some of the promising options that may become available to the practitioner in the near future. These include 1) ultrafiltration, where excess fluid is removed by the application of a minimally invasive extracorporeal blood circuit; 2) digital sound wave analysis, which provides improved specificity for the diagnosis of ADHF; 3) and intermittent infusion therapy, where initial studies suggest infusion therapy with nesiritide may improve chronic outcomes. These applications may be uniquely appropriate for the observation unit environment. While not currently mainstream or standard of care in their current usage, these opportunities may represent foreseeable directions in the early diagnosis and treatment of ADHF. Future research will place these maneuvers into their appropriate diagnostic and therapeutic roles, which will hopefully provide benefit to our patients.

The control of adrenergic function in heart failure: therapeutic intervention

Chronic heart failure is characterised by excess adrenergic activity that augurs a poor prognosis. The reasons for increased adrenergic activity are complex and incompletely understood. The circumstantial evidence relating increased activity to adverse outcome is powerful, but not yet conclusive. In normal subjects, autonomic control of the circulation is predominantly under the control of sympatho-inhibitory inputs from the arterial and cardiopulmonary baroreceptors, with a small input from the excitatory ergo- and chemo-receptors. In heart failure, the situation is reversed, with loss of the restraining input from the baroreceptors and an increase in the excitatory inputs, resulting in excessive adrenergic activity. The circumstantial evidence linking neuroendocrine activation with poor outcome coupled with the clinical success of inhibition of the renin-angiotensin-aldosterone system has long suggested that inhibition of adrenergic activity might be beneficial in heart failure. There is a number of potential ways of achieving this. Improved treatment of heart failure itself may reduce sympathetic drive. There is an interplay between angiotensin II, aldosterone and the sympathetic nervous system, and thus RAAS antagonists, such as angiotensin converting enzyme inhibitors and spironolactone could directly reduce sympathetic activation. Exercise rehabilitation may similarly reduce sympathetic activity.Recently, beta-adrenergic receptor antagonists have been conclusively shown to improve symptoms, reduce hospitalisations and increase survival. However, the demonstration that central reduction of sympathetic activity with agents such as moxonidine increases morbidity and mortality suggests that we do not properly understand the role of sympathetic activation in the pathophysiology of heart failure.

Emergency department management of patients with acute decompensated heart failure

The Acute Decompensated HEart Failure National REgistry (ADHERE(R)) confirms that the management of decompensated heart failure is an emergency department (ED) problem, as more than 75% of patients admitted to the hospital with heart failure arrive through the ED. This emphasizes the need for collaboration among emergency medicine, cardiology, nephrology, and hospitalists in the management of acute decompensated heart failure. Such collaboration is important for several reasons, including the enhancement of patient care. It is also known that most hospitals lose money on heart failure admissions. Strategies that can be employed to limit hospital losses on heart failure include reducing admissions from the ED; decreasing the length of hospital stay; increasing the use of the observation unit; reducing re-admissions, particularly through the first 30 days; and reducing the use of high-resource areas such as the intensive care unit (ICU). This article will focus on initiatives that can be implemented in the ED to help with these strategies. In particular, we will discuss early initiation of therapy and its ability to improve length of stay, reduce re-admissions, and reduce ICU admissions. Use of the observation unit for the management of heart failure will also be discussed as a way of decreasing admissions from the ED.

The cardiovascular implications of hypokalemia

The role of potassium in the progression of cardiovascular disease is complex and controversial. Animal and human data suggest that increases in dietary potassium, decreases in urinary potassium loss, or increases in serum potassium levels through other mechanisms have benefits in several disease states. These include the treatment of hypertension, stroke prevention, arrhythmia prevention, and treatment of congestive heart failure. Recently, the discovery that aldosterone antagonists not only decrease sodium reabsorption and decrease potassium secretion in the nephron, but also decrease pathological injury of such nonepithelial tissues as the myocardium and endothelium, has generated great controversy regarding the actual mechanisms of benefit of these agents. We review the available data and draw conclusions about the relative benefits of modulating potassium balance versus nonrenal effects of aldosterone blockade in patients with cardiovascular disease.

Strategies to reduce length of stay and costs associated with decompensated heart failure

Heart failure (HF) is a major medical problem in the United States, imposing significant economic burden on the health care system. Despite therapeutic advances, HF-associated morbidity and mortality continue to increase. Compliance with therapeutic guidelines for the management of chronic HF is far from ideal, increasing the likelihood that patients will experience multiple episodes of acute decompensated heart failure (ADHF) during the course of HF disease. Prevention, streamlined inpatient care, effective vasoactive therapy, and initiation of proven long-term therapies, including angiotensin-converting enzyme (ACE) inhibitors and beta-blockers, are all targets for improvement. Because of the chronic nature of heart failure, a successful disease management program for ADHF must also include effective outpatient care.

Role of vasopressin antagonists in the management of acute decompensated heart failure

Vasopressin antagonists are a class of neurohormonal antagonists with applications in both the short-term and long-term management of patients with acute decompensated heart failure (ADHF). The pharmacologic effects of vasopressin antagonists include changes in fluid balance and hemodynamics that may improve symptoms and outcomes in patients hospitalized with ADHF. With chronic therapy, vasopressin antagonists offer the potential to improve outcomes through a variety of mechanisms, including more effective treatment of congestion, preservation or improvement of renal function, or a reduction in the use of concomitant loop diuretic therapy. Several vasopressin antagonists are currently in advanced clinical trials for the treatment of ADHF, chronic stable heart failure, and hyponatremia.

A review of the current evidence for the use of angiotensin-receptor blockers in chronic heart failure

Angiotensin-converting enzyme (ACE) inhibitors have a central role in the management of heart failure, reflecting the contribution of the renin-angiotensin-aldosterone system to the pathophysiology of the condition. Angiotensin-receptor blockers (ARBs) bind specifically to the angiotensin type 1 receptor and may offer further benefits compared with ACE inhibitors. Candesartan, losartan and valsartan have all been evaluated in large clinical outcome trials in heart failure. They display marked differences in pharmacokinetics and receptor-binding properties that may contribute to observed differences in outcome. ELITE II found no significant difference in outcome with losartan as compared with captopril. In the Val-Heft trial, valsartan reduced heart failure hospitalisations when added to conventional therapy including an ACE inhibitor in most patients, but had no effect on mortality. The CHARM programme showed that candesartan reduced morbidity and mortality in heart failure with reduced systolic function, both when added to ACE inhibitor therapy or when used as an alternative in patients who are intolerant to ACE inhibitors. Moreover, the CHARM-preserved study suggested that candesartan is beneficial in patients with heart failure and preserved left-ventricular systolic function. A growing body of evidence show that ARBs are an important contribution to the pharmaceutical management of patients with heart failure.

Diuretic usage in heart failure: a continuing conundrum in 2005

Several large well-designed clinical trials have shown that the use of diuretics is beneficial in patients with hypertension. However, similarly robust data regarding their role in chronic heart failure are lacking. Historically, diuretics were developed for treatment of sodium and water retention in oedematous disorders and clinically, they remain the most potent drugs available to relieve symptoms and eliminate oedema in the congested patient with heart failure. In the non-congested patient, however, diuretics continue to be used on a purely clinical basis without sufficient characterization of benefits, adverse effects, and potential influence on mortality. There are also concerns that chronic diuretic usage can cause adverse vascular effects, unfavourable neuroendocrine activation, electrolyte imbalances, and life-threatening arrhythmias. In this article, we review the limited evidence available regarding the benefits and perils of using diuretics in heart failure.

Recent advances in natriuretic peptides in congestive heart failure

Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) are secreted by the heart and play important roles in the compensation of congestive heart failure with their vasodilating, natriuretic, antiproliferative, lusitropic and neurohumoral-modulating properties. Based on these beneficial properties, exogenous BNP was developed as a new treatment for congestive heart failure and approved in the US for acute decompensated heart failure. New therapeutic strategies for heart failure that are currently being investigated include chronic subcutaneous BNP administration and intermittent BNP infusions. Furthermore, strategies combining exogenous BNP with an inhibitor of the BNP-degrading enzyme neutral endopeptidase could contribute to maximising the actions of BNP and reduce the amount of exogenous BNP needed.

The effects of a sliding scale diuretic titration protocol in patients with heart failure

Patients with heart failure (HF) are often instructed to temporarily adjust their diuretic dose. This approach has become routine in some HF management programs; however, no study has specifically examined the effects of a patient-directed flexible diuretic protocol. For the purposes of this study, patients were randomized into a usual care (UC) group (n = 31) or a flexible diuretic titration (DT) group (n = 35). The DT group completed a 6-item diuretic titration protocol once a day, for 3 months. The 6-minute walk distance, plasma B-type natriuretic peptide (NT-BNP), plasma norepinephrine (NE), and quality of life (QOL) were measured at baseline and at 3 months. Hospitalizations, emergency department (ED) visits, and mortality rates were measured at 3 months. Compared to baseline, at 3 months, there was a significant increase in the DT group's 6-minute walk distance (646 +/- 60 ft vs 761 +/- 61 ft, P = .01) and total QOL score (53 +/- 5 vs 38 +/- 5, P = .001), whereas these parameters remained unchanged within the UC group. There were significantly less ED visits in the DT group compared with those in the UC group (3% vs 23%, P = .015). No differences were found between the groups in HF-related hospitalizations or mortality. Within both groups, no differences were found between baseline and 3-month NE or NT-BNP plasma values. Patients with heart failure who used a sliding scale diuretic titration protocol had significant improvements in their exercise tolerance and QOL, had fewer ED visits, and had no change in plasma NE or NT-BNP levels.

Furosemide and the progression of left ventricular dysfunction in experimental heart failure

OBJECTIVES

We tested the hypothesis that furosemide accelerates the progression of left ventricular systolic dysfunction in a tachycardia-induced porcine model of heart failure.

BACKGROUND

Furosemide activates the renin-angiotensin-aldosterone system in patients with congestive heart failure (CHF). Such activation may contribute to CHF progression, but prospective data are lacking.

METHODS

Thirty-two Yorkshire pigs were randomized to furosemide (1 mg/kg intramuscularly daily, mean 16.1 +/- 0.9 mg) or placebo. Thereafter, a pacing model of heart failure was utilized to produce systolic dysfunction in both sets of animals (fractional shortening <0.16 by echocardiogram). The goal was to determine if furosemide would accelerate the progression of left ventricular dysfunction in the "treated" group. After sacrifice, sodium-calcium exchanger currents and their responsiveness to isoproterenol were measured during voltage clamp. All investigators were blinded to treatment assignment.

RESULTS

Furosemide shortened the time to left ventricular dysfunction (35.1 +/- 5.1 days in placebo versus 21.4 +/- 3.2 days for furosemide animals; p = 0.038, log-rank test). By day 14, aldosterone levels were significantly higher in furosemide animals (43.0 +/- 11.8 ng/dl vs. 17.6 +/- 4.5 ng/dl; p < 0.05). Serum sodium was reduced (133.0 +/- 0.9 mmol/l furosemide vs. 135.7 +/- 0.8 mmol/l placebo; p < 0.05), but no difference in norepinephrine, potassium, magnesium, creatinine, or urea nitrogen was present. Basal sodium-calcium exchanger currents were significantly increased and isoproterenol responsiveness depressed by furosemide.

CONCLUSIONS

Tachycardic pigs given furosemide had significant acceleration of both contractile and metabolic features of CHF, including left ventricular systolic dysfunction, elevated serum aldosterone levels, and altered calcium handling in a controlled experimental model of heart failure.

Fiftieth anniversary of aldosterone: from discovery to cardiovascular therapy

Half a century after the elucidation of its molecular structure, aldosterone is generating the greatest interest, not in the fields of endocrinology or renal medicine but in cardiology-where aldosterone over-activation is now perceived as detrimental in heart failure (HF) and ischaemic heart disease. Clinically, excess aldosterone is associated with higher morbidity and mortality after myocardial infarction (MI) and HF. The Randomised Aldactone Evaluation Study (RALES) study in severe chronic heart failure and the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival (EPHESUS) study in post-MI heart failure have shown that use of non-selective and selective aldosterone receptor antagonists, respectively, improves prognosis. The pathophysiological mechanisms underpinning these damaging aldosterone-mediated cardiovascular effects are still being elucidated, but prime candidates include cardiomyocyte necrosis and apoptosis, and myocardial fibrosis resulting in adverse cardiac remodelling, coronary vasculopathy, tachyarrhythmia and positive feedback activation of the renin-angiotensin-aldosterone system. Practical points for consideration when instigating therapy include preferential use of aldosterone receptor antagonists to maintain electrolyte balance whenever loop or thiazide diuretics are used (vulnerable HF patients require higher ranges of potassium and magnesium to minimise propensity for tachyarrthythmia), for renoprotection and for counteracting aldosterone breakthrough despite adequate ACE inhibition; use of the minimum doses of loop diuretics required to lessen activation of the renin-angiotensin-aldosterone system in HF; use of selective aldosterone receptor antagonists to avoid gynaecomastia/mastalgia and impotence; and prophylactic use of aldosterone receptor antagonists to improve prognosis.