Comparison of candesartan, enalapril, and their combination in congestive heart failure: randomized evaluation of strategies for left ventricular dysfunction (RESOLVD) pilot study. The RESOLVD Pilot Study Investigators

Therapeutic potential of angiotensin II receptor antagonists

The circulating renin-angiotensin system plays an important role in cardiovascular homeostasis. More importantly, the local tissue renin angiotensin plays a pivotal role in cell growth and remodelling of cardiomyocytes and on the peripheral arterial vasculature. In addition, the renin angiotensin system is related to apoptosis, control of baroreflex and autonomic responses, vascular remodelling and regulation of coagulation, inflammation and oxidation. The cardioprotective and vascular protective effects of the angiotensin receptive blockade appears to be related to selective blockade of the angiotensin II (A-II) Type I (AT(1)) receptors. However, there is now growing evidence showing that some of the effects of AT-II receptor blockers (ARBs) are related to the activation of the kinin pathways. This paper will review some of the recent mechanisms related to the cardiovascular effects of angiotensin and more specifically of ARBs. This paper will present the novel data on the role of ARB in the development of atherosclerosis, vascular remodelling, coagulation balance and autonomic regulation. Finally, the role of ARBs, used alone or in combination with ACE inhibitor in patients with heart failure, will be discussed.

Results from post-hoc analyses of the CIBIS II trial: effect of bisoprolol in high-risk patient groups with chronic heart failure

BACKGROUND

The beneficial effects of the beta-blocker bisoprolol on mortality and rate of hospitalisation as well as its safety in patients with chronic heart failure has been proven. However, its efficacy in patients in whom beta-blockers have traditionally been contraindicated or caution has been advised has not been clearly determined. Therefore, analyses in high-risk subgroups of patients taking part in CIBIS II have been performed to investigate the effect of bisoprolol in elderly patients, in patients with type 2 diabetes, with renal failure, NYHA functional class IV or concomitantly treated with digitalis, aldosterone antagonists or amiodarone.

METHODS

High-risk subgroups of patients with chronic heart failure taking part in the CIBIS II study were retrospectively analysed with respect to mortality, hospitalisation, combined endpoint of cardiovascular mortality or hospitalisation for cardiovascular reasons and treatment withdrawal as well as cause of death and hospitalisation. Analysis is based on intention-to-treat.

RESULTS

It was demonstrated that in spite of the expected increase in the overall risk of death and hospitalisation, patients who are diabetic, have renal impairment, NYHA class IV symptoms, are elderly, are taking either digitalis, amiodarone or aldosterone antagonists as co-medication benefit equally from beta-blockade with bisoprolol as patients without these complications or drugs. Benefit was shown for the primary endpoint all cause mortality, as well as for the secondary endpoints.

CONCLUSIONS

Contrary to the hitherto prevailing doctrine of not using beta-blockers in high risk patient groups with chronic heart failure, retrospective analyses of the CIBIS II study justify the use of this drug class in patients regardless of age, NYHA functional class, the presence of diabetes, renal impairment or concomitant treatment with digitalis, amiodarone or aldosterone antagonists.

Coadministration of losartan and enalapril exerts additive antiproteinuric effect in IgA nephropathy

Angiotensin-converting enzyme (ACE) inhibitors and AT1-receptor antagonists (ARAs) are widely administered to reduce urinary protein loss and slow the progression of proteinuric nephropathy to end-stage renal failure. Our group recently observed that the combination of ACE inhibitors and ARAs may have an additive antiproteinuric effect, which may occur because ACE inhibitors do not completely reduce angiotensin II (Ang II) production. Ang II is also produced by chymase. Thus, combination therapy better antagonizes the effects of Ang II. The purpose of this study is to ascertain whether the additive antiproteinuric effect of ACE inhibitors plus ARAs is dose dependent and related to the drug-induced reduction in systemic blood pressure. Therefore, enalapril (E; 10 mg/d) and losartan (LOS; 50 mg/d) were randomly administered alone and then in association; initial dosages were doubled when drugs were administered alone and in association. To determine the influence of the drug-dependent effect on reducing blood pressure and the reduction in urinary proteinuria, both ambulatory and office blood pressures were recorded. E and LOS administered alone reduced proteinuria by the same extent; no further reduction was observed when E and LOS alone were administered at a doubled dose. When E and LOS were coadministered, proteinuria decreased by a greater extent compared with E and LOS alone; an additional reduction in proteinuria was observed when combined therapy doses were doubled. The reduction in proteinuria was not correlated with clinical through blood pressure; however, reductions in diastolic and mean ambulatory blood pressures significantly correlated with the decrease in proteinuria, as well as with creatinine clearance. In conclusion, this study shows that combination therapy with E and LOS has an additive dose-dependent antiproteinuric effect that is likely induced by the drug-related reduction in systemic blood pressure. In normotensive proteinuric patients, it is likely that even a small reduction in systemic blood pressure may affect intraglomerular hemodynamics by a great extent because efferent arteriole regulation is hampered more completely by the coadministration of ACE inhibitors and ARAs.

Aldosterone antagonists in the treatment of hypertension and target organ damage

Mineralocorticoids mediate a number of effects besides regulation of fluid and electrolyte balance. Recent evidence has revealed several nontraditional roles, sites of synthesis, and action for these steroids. Aldosterone, the principal mineralocorticoid in humans, appears to be synthesized in physiologically relevant amounts in both the heart and the vasculature, and plays an important role in vessel wall and myocardial remodeling. The genomic effects of aldosterone are mediated through activation of the classic mineralocorticoid receptor, whereas rapid nongenomic effects seem to involve a distinct receptor and result in activation of multiple downstream signaling pathways. Recently, several lines of evidence seem to suggest an important interaction between the nitric oxide and the aldosterone pathway in the adrenal gland and vasculature. The evolution of selective aldosterone receptor antagonists will help us understand the role that mineralocorticoids play in the pathogenesis of hypertension, heart failure, and atherosclerosis.

Health-related quality of life measurement in heart failure: challenges for the new millennium

Health-related quality of life (HRQL), representing a patient-driven end point, has been increasingly emphasized in randomized clinical trials of new heart failure therapies. Measurement of HRQL depends on the use of validated instruments, with attention paid to the timing of administration and analysis of data in the context of conventional morbidity and mortality end points. In a review of HRQL measurement in heart failure drug trials published from 1966 to 1999, we found that important data, such as the number of participating subjects, are often lacking. HRQL is analyzed as a stand-alone end point without consideration of the underlying clinical trajectory of the disease. Improvements in trials methodology are warranted if quality-of-life data are to be meaningful in the determination of drug efficacy in heart failure.

Medical management of mild-to-moderate heart failure before the advent of beta blockers

Clinical trials of beta blockers in heart failure have generally required that patients be receiving optimal drug therapy before randomization to the study medication. Therefore, because beta blockers are used in addition to conventional drug therapy, review of the standard drug therapy of mild-to-moderate heart failure before the advent of beta blockade is essential to understanding the role of beta blockers in the treatment of heart failure. The conventional medical management of systolic heart failure includes angiotensin-converting enzyme (ACE) inhibitors, which should be used as first-line therapy; diuretics, for the management of body fluid-volume excess; digoxin; and some other vasodilators. These therapies have been evaluated in large-scale, randomized, controlled trials. ACE inhibitors have been shown to significantly attenuate disease progression and improve outcome (ie, morbidity and mortality) in patients with mild-to-moderate systolic heart failure. Controversial or unproven therapies include nonglycoside inotropic agents, angiotensin II receptor antagonists, antiarrhythmic agents, anticoagulants, and calcium channel blockers. The pharmacologic management of diastolic heart failure is largely empirical and is directed at reducing symptoms. Symptoms caused by increased ventricular filling pressures may be treated with diuretics and long-acting nitrates. Some calcium channel blockers and most beta blockers prolong diastolic filling time by slowing heart rate, thereby potentially improving the symptoms of diastolic heart failure. Calcium antagonists, beta blockers, diuretics, and ACE inhibitors may also promote regression of left ventricular hypertrophy and thus improve ventricular compliance, possibly preventing the development of diastolic dysfunction. Because randomized controlled trials of diastolic heart failure are lacking, this review focuses on the conventional management of mild-to-moderate systolic heart failure before the advent of beta blockade.

Comparison of the angiotensin II type 1-receptor antagonist YM358 and the angiotensin-converting enzyme inhibitor enalapril in rats with cardiac volume overload

We evaluated the effects of chronic oral administration of an angiotensin II type 1 (AT1)-receptor antagonist YM358 and an angiotensin converting enzyme inhibitor enalapril on hemodynamics and cardiac hypertrophy in rats with volume overload-induced heart failure. We assessed changes of cardiac hemodynamics and cardiac hypertrophy at 2 and 4 weeks after administration of YM358 (3, 30 mg/kg per day) or enalapril (30 mg/kg per day) in abdominal aortocaval shunt rats. YM358 (30 mg/kg) attenuated increases of left ventricle (LV)/body weight (BW), left atrium (LA)/BW, right ventricle (RV)/BW and heart/BW ratios, but did not affect cardiac hemodynamics in shunt rats. Enalapril also reduced the increased LV/BW and heart/BW ratios together with significant reductions of systolic blood pressure, left ventricular systolic pressure and the first derivative of left ventricular pressure. These data suggest that the effects on attenuation of the development of cardiac hypertrophy are not different for YM358 and enalapril, although the effects on cardiac hemodynamics are different for the same dosages. The attenuating action of YM358 on cardiac hypertrophy was independent of the action on hemodynamics and indicated the direct action of the AT1 receptor on the heart.

[New pharmacological agents in heart failure]

Heart failure is a common and growing public health problem, with increasing incidence and prevalence over the last 2 decades. Despite improvements in its current management, heart failure is still associated with significant morbidity and mortality. This has motivated the search for newer therapeutic modalities, which are based on a better understanding on the pathophysiologic events that lead to heart failure. This review summarizes the potential role of new pharmacological agents in the treatment of heart failure. These potential new agents can be classified according to their role in the modulation of the main pathophysiologic abnormalities that characterized heart failure, that include: cellular-extracellular abnormalities, endothelial dysfunction, neurohormonal and immunologic activation.

ADEPT: Addition of the AT1 receptor antagonist eprosartan to ACE inhibitor therapy in chronic heart failure trial: hemodynamic and neurohormonal effects

BACKGROUND

Persistent activation of the renin-angiotensin-aldosterone-system (RAAS) is known to occur in patients with chronic heart failure (CHF) despite treatment with angiotensin-converting enzyme inhibitor (ACE) therapy. When added to ACE inhibitors, angiotensin II type 1 (AT1) antagonists may allow more complete blockade of the RAAS and preserve the beneficial effects of bradykinin accumulation not seen with AT1 receptor blockade alone.

METHODS

Thirty-six patients with stable New York Heart Association class II-IV CHF receiving ACE inhibitor therapy were randomly assigned in a double-blind manner to receive either eprosartan, a specific competitive AT1 receptor antagonist (400 to 800 mg daily, n = 18) or placebo (n = 18) for 8 weeks. The primary outcome measure was left ventricular ejection fraction (LVEF) as measured by radionuclide ventriculography, and secondary measures were central hemodynamics assessed by Swan-Ganz catheterization and neurohormonal effects.

RESULTS

There was no change in LVEF with eprosartan therapy (mean relative LVEF percentage change [SEM] +10.5% [9.3] vs +10.1% [5.0], respectively; difference, 0.4; 95% confidence interval [CI], -20.8 to 21.7; P =.97). Eprosartan was associated with a significant reduction in diastolic blood pressure and a trend toward a reduction in systolic blood pressure compared with placebo (-7.3 mm Hg [95% CI, -14.2 to -0.4] diastolic; -8.9 mm Hg [95% CI, -18.6 to 0.8] systolic). No significant change in heart rate or central hemodynamics occurred during treatment with eprosartan compared with placebo. A trend toward an increase in plasma renin activity was noted with eprosartan therapy. Eprosartan was well tolerated, with an adverse event profile similar to placebo, whereas kidney function remained unchanged.

CONCLUSIONS

When added to an ACE inhibitor, eprosartan reduced arterial pressure without increasing heart rate. There was no change in LVEF after 2 months of therapy with eprosartan.

Angiotensin receptor blockers and aldosterone antagonists in chronic heart failure

Prognosis in congestive heart failure is directly linked to neurohormonal activation. Angiotensin II through the activation of the renin angiotensin aldosterone system has been the principal focus therapy over the last 2 decades. New agents that target selective blockade of the angiotensin II receptor have been introduced in clinical trials for the treatment of heart failure. Aldosterone has been identified as a critically important neurohormone with direct detrimental effects on the myocardium. Aldosterone antagonists have been used in clinical trials to improve mortality in patients with chronic heart failure.

New and emerging pharmacological strategies in the management of chronic heart failure

Chronic heart failure is a complex syndrome involving the activation of multiple cellular, metabolic and neurohumoral pathways following the initial myocardial insult. Because of the complexity of the disease, strategies targeting these multiple systems involved in disease progression are required to maximise the therapeutic benefits of intervention. To this end, there are a number of approaches currently under active evaluation. These include the inhibition of additional neurohormonal vasoconstrictor systems (e.g. endothelin and vasopressin systems), cytokine antagonists (e.g. agents that block tumour necrosis factor-alpha activity), agents that favourably modulate extracellular matrix (e.g. matrix metalloprotease inhibitors) and agents that augment natriuretic peptides.

Recent studies with eplerenone, a novel selective aldosterone receptor antagonist

Activation of the renin-angiotensin-aldosterone system is associated with unsatisfactory outcomes in patients with hypertension and congestive heart failure, in that activation of this system is correlated strongly with both the incidence and extent of end-organ damage. Despite the availability of the angiotensin-converting enzyme inhibitors and the AT1 receptor antagonists, unblocked aldosterone levels remain an important risk factor for cardiovascular disease progression. New preclinical data generated over the past few years strongly support the hypothesis that aldosterone has important deleterious effects on the cardiovascular system independent of the classical action of this hormone on renal epithelial cells. The new selective aldosterone receptor antagonist eplerenone has been shown to produce significant cardioprotective effects in experimental models of cardiovascular disease. Early clinical testing suggests that eplerenone may have important therapeutic benefit in the treatment of hypertension and heart failure.

Terms of reference for Data and Safety Monitoring Committees

The Data and Safety Monitoring Committee (DSMC) constitutes one of the most complex elements of a clinical trial. For this reason, it is critical that all participants in and contributors to a trial understand the functions and responsibilities of the DSMC. Failure to understand the complexity of this group's mission can lead to substantial opportunities for confusion among investigators, sponsors, regulators, and the public, especially if the trial that it monitors must be modified or terminated early.

Difficult cases in heart failure: Raison d'Être behind ACE inhibitors and AT1 receptor combinations in chronic heart failure: chemical nuances or clinical significance?

The following case description serves to illustrate the difficulties often faced in clinical practice in implementing what appear to be fairly simple and clear evidence-based guidelines regarding angiotensin-converting enzyme (ACE) inhibitors and no clear guidelines regarding angiotensin receptor blocker (ARB) use or, more importantly, ACE inhibitor and ARB combinations in chronic heart failure. (c)2001 by CHF, Inc.

Are angiotensin II receptor blockers more efficacious than placebo in heart failure? Implications of ELITE-2. Evaluation of Losartan In The Elderly

In the light of the recent randomized controlled trials in chronic heart failure, it is now commonly assumed that treatment with an angiotensin-receptor blocker (ARB) is equivalent to treatment with an angiotensin-converting enzyme (ACE) inhibitor. We performed an imputed placebo analysis using previous placebo-ACE inhibitor trials and the current ACE inhibitor-ARB comparison studies, which shows that ARBs may not even be superior to placebos, let alone an ACE inhibitor.

[Drug prospects in the treatment of heart insufficiency]

Pharmacological and validated treatment of chronic heart failure (HF) includes successively angiotensin converting enzyme inhibitors (ACEi), beta-blockers and antialdosterone, which is associated with diuretics. The effectiveness of this manner in which to block more and more hormonal systems demonstrate the validity of the "hormonal" paradigm to explain heart failure. Therefore broader educational means are required to increase the prescription of these drugs for HF. Several questions about these drugs remain unresolved: HF with preserved systolic function and elderly patients, class effect, and the role of antagonists of angiotensin II receptors (as an alternative or associated with ACEi). Other short- and mid-term pharmacological perspectives target target hormonal systems and cytokines: endothelin-receptor antagonists, inhibition of natriuretic peptide degradation (via neutral endopeptidase), and newer drugs acting against TNF such as etanercept. Moreover, recent knowledge about molecular mechanisms of myocardium remodeling allows new drug strategies with target more specifically remodeling such as metalloproteinases. Finally, these perspectives should be largely modified by on-going research in the field of genomics.

Combined therapy with an angiotensin II receptor blocker and an angiotensin-converting enzyme inhibitor in heart failure

OBJECTIVE

To evaluate the safety, tolerability, and efficacy of chronic combination therapy with an angiotensin-converting enzyme (ACE) inhibitor and an angiotensin II receptor blocker (ARB) in the management of heart failure.

DATA SOURCES

Clinical literature was accessed through MEDLINE (January 1966-June 2000). Key search terms included angiotensin-converting enzyme inhibitor; losartan; combined modality therapy; drug effects; heart failure, congestive; and receptors, angiotensin.

DATA SYNTHESIS

Heart failure is widely prevalent and continues to be associated with high morbidity and mortality, even with currently recommended care. At the moderate doses studied for patients with mild heart failure in brief trials, combined ACE inhibitor and ARB therapy was well tolerated and had an additive effect in reducing blood pressure and relieving symptoms of heart failure.

CONCLUSIONS

An ARB combined with an ACE inhibitor may benefit heart failure patients who are receiving all other recommended therapies. Further trials are needed to evaluate long-term safety effectiveness, quality of life, and survival before the combination can be recommended for routine use.

New competition in the realm of renin-angiotensin axis inhibition; the angiotensin II receptor antagonists in congestive heart failure

OBJECTIVE

To critically review the studies comparing angiotensin II (AgII) receptor antagonists with placebo or angiotensin-converting enzyme (ACE) inhibitors in patients with congestive heart failure (CHF).

DATA SOURCES

A MEDLINE search (1988 to January 2000) was used to identify pertinent literature. Additional references were also retrieved from selected articles.

STUDY SELECTION

As most published CHF studies were performed with candesartan and losartan, these agents are the main focus of this article. However, all identified comparative clinical studies were reviewed and included, regardless of the agent used.

DATA SYNTHESIS

AgII receptor antagonists inhibit the effects of AgII at its sub-type 1 receptor, independently of AgII's synthesis pathway. They present a hemodynamic profile similar to that of ACE inhibitors, without reflex neurohormonal activation. They have been shown to be at least as effective as ACE inhibitors in improving symptoms, exercise capacity, and New York Heart Association functional class in CHF patients. Although the ELITE (Evaluation of Losartan in the Elderly) trial suggested that losartan improved survival compared with captopril, this study was not designed to look at mortality. ELITE-II, an adequately powered study, showed no difference in mortality rates between patients taking captopril and those taking losartan. The combination of AgII receptor antagonists and ACE inhibitors provides additional benefit on blood pressure lowering and prevention of ventricular remodeling. AgII receptor antagonists are well tolerated, with an incidence of adverse effects similar to or lower than that of ACE inhibitors. Their lack of effect on bradykinin degradation might explain their lower incidence of cough.

CONCLUSIONS

The data cumulated thus far in patients with CHF highlight that ACE inhibitors must remain the treatment of choice and that AgII receptor antagonists may be considered as an acceptable alternative for patients who are intolerant to ACE inhibitors.

Serum erythropoietin in heart failure patients treated with ACE-inhibitors or AT(1) antagonists

BACKGROUND

Erythropoietin (Epo), a growth factor produced by the kidney, is important in heart failure patients to promote oxygen delivery to tissues. Seventy-two chronic heart failure (CHF) patients at our outpatient clinic were subjected to morning serum Epo-level measurements and classified according to NYHA criteria.

RESULTS

Forty-eight patients of classes III and IV had a significantly elevated serum Epo-level of 42.9+/-40.3 mIU/ml (mean+/-1 S.D.) when compared to the mean level of 24 patients of classes I and II who had a normal range mean value of 13.4+/-6.2 mIU/ml (P<0.05). Patients on angiotensin-converting enzyme (ACE) inhibitors showed a trend towards lower serum Epo-levels compared to patients treated with angiotensin-II type-1 receptor antagonists (AT(1) antagonists) (levels: 33.3+/-35.6 mIU/ml and 43.6+/-38.1 mIU/ml). This trend did not, however, reach statistical significance (P=0.36).

CONCLUSION

We suggest that a desirable Epo increase in class III and IV CHF patients could be achieved by either recombinant human Epo administration or, possibly, by appropriate selection of the concomitant medical therapy. A large prospective study shall investigate the possible advantage of AT(1) antagonists over ACE-inhibitors with regard to Epo effect.

Baseline demographics of the Valsartan Heart Failure Trial. Val-HeFT Investigators

BACKGROUND

The Valsartan Heart Failure Trial (Val-HeFT) is the first large-scale randomized, multinational clinical study to assess the efficacy and safety of valsartan, an angiotensin II receptor blocker, added to conventional therapy, including angiotensin-converting enzyme inhibitors, in heart failure patients. A total of 5010 patients with an ejection fraction <40% have been randomized to either valsartan titrated to 160 mg b.i.d. or to placebo.

AIMS

Baseline characteristics of patients in Val-HeFT are presented and compared with other major clinical trials in heart failure.

METHODS

Baseline data were collected and summary statistics calculated.

RESULTS

The study population has a mean age of 62.7 years and is 80% male, 90.3% white, 6.9% black, and 2.8% Asian. Antecedent coronary heart disease is reported in 57.2% of patients. Angiotensin-converting enzyme inhibitors are prescribed for 92.7% of patients, diuretics for 85.8%, digoxin for 67.3%, and beta-blockers for 35.6%. Subgroup comparisons by age, sex, race and ejection fraction quartile show small differences in baseline characteristics.

CONCLUSION

Overall the Val-HeFT population is generally representative of the population of patients with mild to moderate heart failure in industrialized countries.

New drugs in the treatment of heart failure

New therapeutic strategies as well as the development of drugs with more specific targets have been fueled by disappointments in the treatment of adult heart failure. Calcium sensitizers, vesnarinone and angiotensin channel blockers will be addressed in this manuscript. The physiologic and pharmacologic principles that justify their use in the management of heart failure are reviewed. Calcium sensitizers increase myocardial contractility and in part they bypass the adenylyl cyclase cascade, which gives them a more favorable energy profile. Vesnarinone is a quinolinone derivative with ion channel modulation properties, which result in a positive inotropic effect and prolongation of the action potential. In addition vesnarinone has immunomodulatory properties. Angiotensin-converting enzyme inhibitors are the cornerstones for the treatment of heart failure. The discovery of some putative drawbacks to ACE inhibition has challenged this supremacy. Angiotensin receptor blockers have been developed hoping to overcome these deficiencies. Myocardial developmental differences highlight the shortcomings of attempting to extrapolate data on drugs and cellular physiology in adults to children. Studies are needed addressing standards of care, quality of life, morbidity and mortality, neurohumoral activation, its modulation and the consequences of these therapies in pediatric heart failure.

The role of the renin-angiotensin-aldosterone system in the management of heart failure

Numerous clinical trials have highlighted the role of the renin-angiotensin-aldosterone (RAA) system in the development and progression of heart failure. Over 30 randomized, controlled trials have evaluated the effects of angiotensin-converting enzyme (ACE) inhibitors on morbidity and mortality in over 7,000 patients with heart failure. Cumulative evidence from these trials shows that these agents significantly reduce mortality and hospitalizations, slow disease progression, and improve exercise tolerance and New York Heart Association class. The Heart Failure Society of America guidelines recommend ACE inhibitors as standard therapy for patients with left ventricular systolic dysfunction. The angiotensin receptor blockers and spironolactone offer alternative and perhaps complimentary mechanisms by which the RAA system may be therapeutically manipulated. The role of these therapies in treating heart failure is discussed.

ACE inhibition or angiotensin receptor blockade: impact on potassium in renal failure. VAL-K Study Group

BACKGROUND

Inhibition of the renin-angiotensin system is known to raise serum potassium [K(+)] levels in patients with renal insufficiency or diabetes. No study has evaluated the comparative effects of an angiotensin-converting enzyme (ACE) inhibitor versus an angiotensin receptor blocker (ARB) on the changes in serum [K(+)] in people with renal insufficiency.

METHODS

The study was a multicenter, randomized, double crossover design, with each period lasting one month. A total of 35 people (21 males and 14 females, 19 African Americans and 16 Caucasian) participated, with the mean age being 56 +/- 2 years. Mean baseline serum [K(+)] was 4.4 +/- 0.1 mEq/L. The glomerular filtration rate (GFR) was 65 +/- 5 mL/min/1.73 m(2), and blood pressure was 150 +/- 2/88 +/- 1 mm Hg. The main outcome measure was the difference from baseline in the level of serum [K+], plasma aldosterone, and GFR following the initial and crossover periods.

RESULTS

For the total group, serum [K(+)] changes were not significantly different between the lisinopril or valsartan treatments. The subgroup with GFR values of < or = 60 mL/min/1.73 m(2) who received lisinopril demonstrated significant increases in serum [K(+)] of 0.28 mEq/L above the mean baseline of 4.6 mEq/L (P = 0.04). This increase in serum [K(+)] was also accompanied by a decrease in plasma aldosterone (P = 0.003). Relative to the total group, the change in serum [K(+)] from baseline to post-treatment in the lisinopril group was higher among those with GFR values of < or = 60 mL/min/1.73 m(2). The lower GFR group taking valsartan, however, demonstrated a smaller rise in serum [K(+)], 0.12 mEq/L above baseline (P = 0.1), a 43% lower value when compared with the change in those who received lisinopril. This blunted rise in [K(+)] in people taking valsartan was not associated with a significant decrease in plasma aldosterone (P = 0.14).

CONCLUSIONS

In the presence of renal insufficiency, the ARB valsartan did not raise serum [K(+)] to the same degree as the ACE inhibitor lisinopril. This differential effect on serum [K(+)] is related to a relatively smaller reduction in plasma aldosterone by the ARB and is not related to changes in GFR. This study provides evidence that increases in serum [K(+)] are less likely with ARB therapy compared with ACE inhibitor therapy in people with renal insufficiency.

Combined treatment with losartan and an ACE inhibitor in mild to moderate heart failure: results of a double-blind, randomized, placebo-controlled trial

BACKGROUND

Although the beneficial effects of angiotensin-converting enzyme (ACE) inhibitors in patients with heart failure are well recognized, there are theoretical advantages in combining ACE inhibition with angiotensin (AT)1 receptor antagonism.

METHODS

Twenty patients with mild to moderate heart failure and maximally treated with an ACE inhibitor were randomly assigned to losartan or placebo. Patients underwent repeated assessment of exercise tolerance, quality of life, central and regional hemodynamics, and neurohumoral and biochemical parameters over a period of 12 weeks.

RESULTS

Losartan treatment was well tolerated in terms of adverse events, heart rate, and blood pressure response, and there were no significant changes in serum creatinine or potassium. After 12 weeks of treatment, no significant differences were observed between the losartan and placebo groups in exercise tolerance, quality of life, central and regional hemodynamics, or neurohumoral parameters.

CONCLUSIONS

In patients with mild to moderate heart failure already maximally treated with an ACE inhibitor, additional treatment with losartan is well tolerated, but we have not observed any significant improvement in exercise capacity, quality of life, central and regional hemodynamics, or neurohormones. Our data suggest that the combination of losartan with an ACE inhibitor does not offer any substantial advantages over treatment with an ACE inhibitor alone in these patients.

Optimal strategies for preventing progression of renal disease: should angiotensin converting enzyme inhibitors and angiotensin receptor blockers be used together?

Interruption of the renin-angiotensin system (RAS) with angiotensin converting enzyme (ACE) inhibitors or angiotensin AT(1) receptor blockers has been shown to delay progression in a variety of renal diseases, suggesting that the RAS, and its major effector molecule, angiotensin II, are important players in renal pathophysiology. Both antagonists combine inhibition of deleterious effects of angiotensin II with activation of potentially beneficial pathways mediated by nitric oxide and prostaglandins. Some concerns have been raised about the completeness of the RAS blockade achieved by these agents. ACE-independent pathways can generate angiotensin II, whereas increases in angiotensin II levels may compete with the AT(1) receptor blocker at the receptor site. It has been suggested that an ACE inhibitor/AT(1) receptor blocker combination offers a better therapeutic effect than treatment with either agent alone. In this review, we focus on mechanisms of actions of ACE inhibitors and AT(1) receptor blockers, implicate them in the rationale for the use of an ACE inhibitor/AT(1) receptor blocker combination, and discuss evidence evaluating the renal effects of the combination as compared to the effects of a single agent. There is a surprising lack of information about the nephroprotective potential of the combination, allowing no consistent conclusions about the superiority of the combination over the single agent. Several experimental and clinical reports suggest that in some conditions, the combination may be beneficial. Rather than providing unequivocal evidence for the use of combination treatment in the renal disease, these studies should be considered as stimuli for more detailed exploration of this issue.

Cardioprotection induced by AT1R blockade after reperfused myocardial infarction: association with regional increase in AT2R, IP3R and PKCepsilon proteins and cGMP

BACKGROUND

We hypothesized that the cardioprotective effect of angiotensin II (AngII) type 1 receptor (AT(1)R) blockade during in vivo ischemia-reperfusion (IR) might be associated with an increase in AngII type 2 receptor (AT(2)R) protein, as well as 1,4,5-inositol trisphosphate type 2 receptor (IP(3)R) and protein kinase C(epsilon) (PKC(epsilon)) proteins and cyclic guanosine 3',5' monophosphate (cGMP).

METHODS AND RESULTS

We studied the effects of the AT(1)R blocker, candesartan, on in vivo left ventricular (LV) systolic and diastolic function and remodeling (echocardiogram/Doppler) and hemodynamics during canine reperfused anterior infarction (90-minute ischemia, 120-minute reperfusion), and ex vivo infarct size and AT(1)R/AT(2)R, IP(3)R, and PKC(epsilon) proteins (immunoblots), and cGMP (enzyme immunoassay). Compared with controls, candesartan (1 mg/kg intravenously over 30-minute preischemia) inhibited the AngII pressor response, decreased preload and afterload, improved LV systolic and diastolic function, limited LV remodeling, decreased infarct size (55% vs 27% risk; P <.000003), markedly increased AT(2)R, IP(3)R, and PKC(epsilon) proteins in the infarct zone, but not the AT(1)R protein, and increased infarct more than noninfarct cGMP.

CONCLUSIONS

The overall results suggest that cardioprotective effects of AT(1)R blockade on acute IR injury might involve AT(2)R activation and downstream signaling via IP(3)R, PKC(epsilon), and cGMP.

The importance of early intervention in CHF--signs and symptom relief

Effective treatments of congestive heart failure (CHF) must not only reduce mortality, but should also reduce the severity of the signs and symptoms of the syndrome, as these can have a major impact on quality of life. Early intervention can help to make everyday activities easier for patients with CHF and may slow disease progression. This review provides an overview of the efficacies of various therapies in improving the signs and symptoms of CHF, with particular reference to recent data from randomised, double-blind studies of patients receiving the AT(1)-receptor blocker, candesartan cilexetil.

Neurohumoral blockade in CHF management

Is heart failure an endocrine disease? Historically, congestive heart failure (CHF) has often been regarded as a mechanical and haemodynamic condition. However, there is now strong evidence that the activation of neuroendocrine systems, like the renin-angiotensin-aldosterone system (RAAS) and sympathetic nervous system, as well as the activation of natriuretic peptides, endothelin and vasopressin, play key roles in the progression of CHF. In this context, agents targeting neurohormones offer a highly rational approach to CHF management, with ACE inhibitors, aldosterone antagonists and beta-adrenergic blockade improving the prognosis for many patients. Although relevant improvements in clinical status and survival can be achieved with these drug classes, mortality rates for patients with CHF are still very high. Moreover, most patients do not receive these proven life-prolonging drugs, partially due to fear of adverse events, such as hypotension (with ACE inhibitors), gynaecomastia (with spironolactone) and fatigue (with beta-blockers). New agents that combine efficacy with better tolerability are therefore needed. The angiotensin II type 1 (AT(1))-receptor blockers have the potential to fulfil both these requirements, by blocking the deleterious cardiovascular and haemodynamic effects of angiotensin II while offering placebo-like tolerability. As shown with candesartan, AT(1)-receptor blockers also modulate the levels of other neurohormones, including aldosterone and atrial natriuretic peptide (ANP). Combined with its tight, long-lasting binding to AT(1)-receptors, this characteristic gives candesartan the potential for complete blockade of the RAAS-neurohormonal axis, along with the great potential to improve clinical outcomes.

The safety and tolerability of candesartan cilexetil in CHF

The management of congestive heart failure (CHF) continues to represent a major therapeutic challenge. The primary goal of any treatment is the improvement of symptoms with a reduction in CHF related morbidity and a neutral or beneficial effect on mortality. The number of hospitalisations is considered an important measure of morbidity and quality-of-life in these patients. This pooled safety analysis was performed on adverse event data from five placebo-controlled studies involving a total of 1893 patients, 1287 of whom received candesartan cilexetil and 606 of whom received placebo. These were the only placebo-controlled phase II and III studies of candesartan safety available at the time of the analysis, and investigated the efficacy and safety of candesartan cilexetil in patients with CHF. None was designed as an endpoint trial. A blinded, independent review of all adverse event data was performed to assess all-cause mortality and unexpected deaths, and hospitalisations for acute deterioration of CHF, chronic progression of CHF, other intercurrent events, or accidental injury/attempted suicide. The descriptive analysis included crude and cumulative incidence rates for mortality and cardiac and non-cardiac morbidity using the Kaplan-Meier method and the log-rank test. The sample population was predominantly (approximately two thirds) male, with a median age of 61 years (range: 20-89 years). The median age for women in the sample population was 66 years (range: 26-86 years). Patients received candesartan cilexetil, 2-32 mg, over a median period of 84 days (range: 1-418 days), or placebo over a median period of 85 days (range: 1-398 days). The results demonstrated a clinically non-significant trend for all relevant events (deaths and hospitalisations, whether related to CHF or not) to occur less frequently in patients receiving candesartan cilexetil than in patients receiving placebo (deaths - candesartan cilexetil: 1.6%, placebo: 1.8%; hospitalisations - candesartan cilexetil: 7.2%, placebo: 10.9%). There was a significant treatment difference in CHF hospitalisations (candesartan cilexetil: 3.0% vs. placebo: 5.6%). The time to event analysis revealed that significantly fewer hospitalisations due to CHF occurred in the group receiving candesartan cilexetil than in the group receiving placebo. This treatment difference persisted throughout therapy (log-rank test; p < 0.028). These results show the safety of candesartan cilexetil, compared with placebo, in the treatment of patients with CHF.

Rationale for the use of combination angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker therapy in heart failure

BACKGROUND

Heart failure (HF) is a major cause of morbidity and mortality in the United States. The renin-angiotensin system (RAS) plays a major role in its pathophysiology, and angiotensin-converting enzyme (ACE) inhibitors are the cornerstone of therapy. However, HF continues to progress despite this therapy, perhaps because of production of angiotensin II by alternative pathways, which lead to direct stimulation of the angiotensin II receptor. Angiotensin II receptor blocker (ARB) therapy alone or in combination with the ACE inhibitor is a promising approach to block the RAS and slow HF progression more completely.

METHODS

The current medical literature on the pathophysiology of HF and the use of ACE inhibitors and ARBs was extensively reviewed.

RESULTS

Evidence from basic science, experimental animals, and clinical trials provides data on the safety and efficacy of RAS inhibition with ACE inhibitors and ARBs as monotherapy and in combination. Data from the Evaluation of Losartan in the Elderly (ELITE) II trial indicate that ARBs alone do not appear to be more effective than ACE inhibitors in HF, but studies evaluating their use in combination are currently ongoing.

CONCLUSIONS

The addition of an ARB offers more complete angiotensin II receptor blockade of the RAS than can be obtained by ACE inhibitors alone. Combination therapy preserves the benefits of bradykinin potentiation offered by ACE inhibitors while providing potential antitrophic influences of AT(2) receptor stimulation and may play an increased role in the treatment of chronic HF in the future.

Effects of angiotensin II AT1-receptor blockade on coronary dynamics, function, and structure in postischemic heart failure in rats

Angiotensin II AT1-receptor blockers (AT1-s) prolong survival in experimental postischemic (coronary artery ligation) heart failure (CHF) in rats. The goal of this study was to investigate whether potential beneficial effects of short- and/or long-term treatment with AT1-s on coronary dynamics, function, and structure develop along with the drug-induced survival prolongation in this model. Coronary blood flow was measured (fluorescent microspheres) in conscious sham, untreated, and irbesartan-treated (50 mg/kg daily for 6 weeks or 6 months, starting 8 days after surgery) CHF rats at baseline and at maximal vasodilatation induced by dipyridamole, and coronary dilatation reserve (CDR) was calculated as the ratio of maximal to baseline coronary flow. Coronary endothelial function was assessed in vitro by measuring the coronary relaxant responses to acetylcholine in the three groups of animals. Finally, cardiac hypertrophy and pericoronary fibrosis also were investigated. In CHF rats, left (LV) and right (RV) ventricular CDR were markedly depressed at both 7 weeks and 6 months after ligation, whereas coronary endothelial function was significantly impaired only after 6 months. Short-term AT1-receptor blockade with irbesartan did not prevent CDR deterioration at 7 weeks, nor did it significantly oppose cardiac hypertrophy and pericoronary fibrosis development. Prolonged AT1-receptor blockade prevented both RV CDR deterioration and coronary endothelial function impairment. It also limited significantly the increase in LV end diastolic pressure and the development of cardiac hypertrophy and pericoronary fibrosis. In conclusion, in postischemic CHF in rats, alterations of CDR precede those of coronary endothelial function. Long-, but not short-term AT1-receptor blockade prevents endothelial function degradation, opposes RV CDR impairment, prevents pericoronary fibrosis development, and improves systemic hemodynamics. These effects of AT1-s on coronary dynamics, function, and structure (i.e., on myocardial perfusion) may contribute to the drug-induced survival prolongation in this model.

Enhanced reduction of myocardial infarct size by combined ACE inhibition and AT(1)-receptor antagonism

The effects of the angiotensin-converting-enzyme inhibitor (ACEI) ramiprilat, the angiotensin II type 1 receptor antagonist (AT(1)A) candesartan, and the combination of both drugs on infarct size (IS) resulting from regional myocardial ischaemia were studied in pigs. Both ACEI and AT(1)A reduce myocardial IS by a bradykinin-mediated process. It is unclear, however, whether the combination of ACEI and AT(1)A produces a more pronounced IS reduction than each of these drugs alone. Forty-six enflurane-anaesthetized pigs underwent 90 min low-flow ischaemia and 120 min reperfusion. Systemic haemodynamics (micromanometer), subendocardial blood flow (ENDO, microspheres) and IS (TTC-staining) were determined. The decreases in left ventricular peak pressure by ACEI (by 9+/-2 (s.e. mean) mmHg), AT(1)A (by 11+/-2 mmHg) or their combination (by 18+/-3 mmHg, P<0.05 vs ACEI and AT(1)A, respectively) were readjusted by aortic constriction prior to ischaemia. With placebo (n=10), IS averaged 20.0+/-3.3% of the area at risk. IS was reduced to 9.8+/-2.6% with ramiprilat (n=10) and 10.6+/-3.1% with candesartan (n=10). Combined ramiprilat and candesartan (n=10) reduced IS to 6.7+/-2.1%. Blockade of the bradykinin-B(2)-receptor with icatibant prior to ACEI and AT(1)A completely abolished the reduction of IS (n=6, 22.8+/-6.1%). The relationship between IS and ischaemic ENDO with placebo was shifted downwards by each ACEI and AT(1)A and further shifted downwards with their combination (P<0.05 vs all groups); icatibant again abolished such downward shift. The combination of ACEI and AT(1)A enhances the reduction of IS following ischaemia/reperfusion compared to a monotherapy by either drug alone; this effect is mediated by bradykinin.

Why we need new strategies in CHF management

Despite recent improvements in drug therapy, the prevalence of congestive heart failure (CHF) continues to rise, as a result of the increasing proportion of older people in the population and factors such as greater survival rates after myocardial infarction. More effective management strategies for CHF are therefore needed urgently. The angiotensin II type 1 (AT(1))-receptor blockers might contribute to such strategies, offering placebo-like tolerability and showing promise in early trials of their use in CHF. Large-scale outcome studies, currently underway, will provide further evidence of the value of AT(1)-receptor blockers in CHF. In addition, the involvement of specially trained nurses in patient education and monitoring should enhance compliance with both existing and novel therapies, and thus help to increase the overall efficacy of holistic strategies for CHF management.

Theoretical basis and clinical evidence for differential effects of angiotensin-converting enzyme inhibitors and angiotensin II receptor subtype 1 blockers

Drugs that block the renin-angiotensin system have multiple mechanisms of action that may be beneficial in stabilizing or delaying progression of renal disease. The most important of these actions is the simultaneous control of both systemic and glomerular capillary hypertension. Angiotensin-converting enzyme (ACE) inhibitors are a class of drugs that have proven antihypertensive and antiproteinuric effects, with a demonstrated ability to delay progression of renal disease in conjunction with the ability to reduce systemic blood pressure. The mechanism of action for these drugs remains poorly described, but depends in part on an ability to reduce plasma angiotensin II levels and increase plasma bradykinin levels. Angiotensin II receptor subtype 1 (AT1) blockers differ in their mechanism of action from the ACE inhibitors. These drugs primarily block the binding of angiotensin II to its type 1 site. In so blocking the type 1 binding site, however, greater levels of circulating angiotensin II result, and the resultant biologic activity of angiotensin II or its metabolites such as angiotensin(1-7) and angiotensin(3-8) may be more directed to other angiotensin-binding sites. AT1 blockers have similar antihypertensive and antiproteinuric effects to those of ACE inhibitors and they may prove to be as useful as ACE inhibitors in delaying progression of renal disease. Because ACE inhibitors and AT1 blockers inhibit the renin-angiotensin system by different mechanisms, there is a possibility that combining them in clinical practice may prove efficacious for lowering blood pressure and for providing target organ protection.

Characterization of cardioprotection mediated by AT2 receptor antagonism after ischemia-reperfusion in isolated working rat hearts

BACKGROUND

Whether cardioprotection induced by the angiotensin II (AngII) type 2 receptor (AT(2)R) antagonist PD123,319 (PD) after ischemia-reperfusion (IR) is influenced by the concentration of PD, presence of AngII, timing of exposure, or inhibition of proton production from glucose metabolism is not known.

METHODS AND RESULTS

We examined these factors in isolated working rat hearts subjected to IR injury, no treatment (control), or treatment with N(6)-cyclohexyl adenosine (CHA, 0.5 micromol/L), an adenosine A(1) receptor agonist that induces cardioprotection by decreasing protons ("positive" control). Compared with control, 1 micromol/L PD present throughout IR improved recovery of left ventricular work (73 +/- 5 vs. 40 +/- 8%) to the level with CHA (82 +/- 5%), but 0.1 micromol/L PD did not (58 +/- 6 vs. 40 +/- 8%). AngII (1 nmol/L) did not effect postischemic recovery associated with 1 micromol/L PD (73 +/- 7%) but improved that associated with 0.1 micromol/L PD (86 +/- 3%). PD (1 micromol/L), present solely during reperfusion, enhanced postischemic left ventricular recovery to 72 +/- 5%. Also, PD (1 micromol/L) did not affect glycolytic rates or proton production in nonischemic or IR hearts.

CONCLUSION

PD-induced cardioprotection is 1) PD concentration-dependent, 2) AngII-sensitive, 3) mediated during reperfusion, and 4) independent of proton production, suggesting that reduction in IR injury and indirect AT(1)R stimulation might be involved.