Dose-related beneficial long-term hemodynamic and clinical efficacy of irbesartan in heart failure

Neurohormones, inflammatory mediators, and cardiovascular injury in the setting of heart failure

Neurohormones and inflammatory mediators have effects in both the heart and the peripheral vasculature. In patients with heart failure (HF), neurohormonal activation and increased levels of inflammatory mediators promote ventricular remodeling and development of HF, as well as vascular dysfunction and arterial stiffness. These processes may lead to a vicious cycle, whereby arterial stiffness perpetuates further ventricular remodeling leading to exacerbation of symptoms. Although significant advances have been made in the treatment of HF, currently available treatment strategies slow, but do not halt, this cycle. The current treatment for HF patients involves the inhibition of neurohormonal activation, which can reduce morbidity and mortality related to this condition. Beyond benefits associated with neurohormonal blockade, other strategies have focused on inhibition of inflammatory pathways implicated in the pathogenesis of HF. Unfortunately, attempts to target inflammation have not yet been successful to improve prognosis of HF. Further work is required to interrupt key maladaptive mechanisms involved in disease progression.

Perceived risk profile and treatment optimization in heart failure: an analysis from BIOlogy Study to TAilored Treatment in chronic heart failure

Background

Achieving target doses of angiotensin‐converting‐enzyme inhibitor/angiotensin‐receptor blockers (ACEi/ARB) and beta‐blockers in heart failure with reduced ejection fraction (HFrEF) is often underperformed. In BIOlogy Study to TAilored Treatment in chronic heart failure (BIOSTAT‐CHF) study, many patients were not up‐titrated for which no clear reason was reported. Therefore, we hypothesized that perceived‐risk profile might influence treatment optimization.

Methods

We studied 2100 patients with HFrEF (LVEF≤40%) to compare the clinical characteristics and adverse events associated with treatment up‐titration (after a 3‐month titration protocol) between; a) patients not reaching target doses for unclear reason; b) patients not reaching target doses due to symptoms and/or side effects; c) patients reaching target doses.

Results

For ACEi/ARB, (a), (b) and (c) was observed in 51.3%, 25.9% and 22.7% of patients, respectively. For beta‐blockers, (a), (b) and (c) was observed in 67.5%, 20.2% and 12.3% of patients, respectively. By multinomial logistic regression analysis for ACEi/ARB, patients in group (a) and (b) had lower blood pressure and poorer renal function, and patients in group (a) were older and had lower ejection fraction. For beta‐blockers, patients in group (a) and (b) had more severe congestion and lower heart rate. At 9 months, adverse events (i.e., hypotension, bradycardia, renal impairment, and hyperkalemia) occurred similarly among the three groups.

Conclusions

Patients in whom clinicians did not give a reason why up‐titration was missed were older and had more co‐morbidities. Patients in whom up‐titration was achieved did not have excess adverse events. However, from these observational findings, the pattern of subsequent adverse events among patients in whom up‐titration was missed cannot be determined.

Mega-trials in heart failure: effects of dilution in examination of new therapies

AIMS

Over the last 30 years, many medicine development programmes in acute and chronic heart failure (HF) with preserved ejection fraction (HFpEF) have failed, in contrast to those in HF with reduced ejection fraction (HFrEF). We explore how the neutral results in larger HF trials may be attributable to chance and/or the dilution of statistical power.

METHODS AND RESULTS

Using simulations, we examined the probability that a positive finding in a Phase 2 trial would result in the study of a truly effective medicine in a Phase 3 trial. We assessed the similarity of clinical trial and registry patient populations. We conducted a meta-analysis of paired Phase 2 and 3 trials in HFrEF and acute HF examining the associations of trial phase and size with placebo event rates and treatment effects for HF events and death. We estimated loss in trial power attributable to dilution with increasing trial size. Appropriately powered Phase 3 trials should have yielded ∼35% positive results. Patient populations in Phase 3 trials are similar to those in Phase 2 trials but both differ substantially from the populations of 'real-life' registries. We observed decreasing placebo event rates and smaller treatment effects with increasing trial size, especially for HF events (and less so for mortality). This was more pronounced in trials in acute HF patients.

CONCLUSIONS

The selection of more positive Phase 2 trials for further development does not explain the failure of HFpEF and acute HF medicine development. Increasing sample size may lead to reduced event rates and smaller treatment effects, resulting in a high rate of neutral Phase 3 trials.

Higher versus lower doses of ACE inhibitors, angiotensin-2 receptor blockers and beta-blockers in heart failure with reduced ejection fraction: Systematic review and meta-analysis

Background

Current heart failure (HF) guidelines recommend titrating angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blockers (ARBs) and beta-blockers (BBs) to target doses used in pivotal placebo-controlled randomized controlled trials (RCTs). Despite a number of RCTs comparing different doses (i.e. higher versus lower doses) of ACEIs, ARBs and BBs, the effects of higher versus lower doses on efficacy and safety remains unclear. For this reason, we performed a systematic review and meta-analysis to evaluate the efficacy and safety of higher versus lower doses of ACEIs, ARBs and BBs in patients with HFrEF.

Methods

We searched MEDLINE, Embase and the Cochrane Central Register of Controlled Trials (CENTRAL) via Ovid from inception to April 25^th, 2018 and opentrials.net and clinicaltrials.gov for relevant trials that compared different doses of medications in heart failure. We analyzed trials by drug class (ACEIs, ARBs, and BBs) for efficacy outcomes (all-cause mortality, cardiovascular mortality, all-cause hospitalizations, HF hospitalizations, HF worsening). For safety outcomes, we pooled trials within and across drug classes.

Results

Our meta-analysis consisted of 14 RCTs. Using GRADE criteria, the quality of evidence for ACEIs and ARBs was assessed as generally moderate for efficacy and high for adverse effects, whereas overall quality for BBs was very low to low. Over ~2–4 years higher versus lower doses of ACEIs, ARBs or BBs did not significantly reduce all-cause mortality [ACEIs relative risk (RR) 0.94 (95% confidence interval 0.87–1.02)], ARBs RR 0.96 (0.87–1.04), BBs RR 0.25 (0.06–1.01)] or all cause hospitalizations [ACEIs relative risk (RR) 0.94 (95% confidence interval 0.86–1.02)], ARBs RR 0.98 (0.93–1.04), BBs RR 0.93 (0.39–2.24)]. However, all point estimates favoured higher doses. Higher doses of ARBs significantly reduced hospitalization for HF [RR 0.89 (0.80–0.99)– 2.8% ARR], and higher doses of ACEIs and ARBs significantly reduced HF worsening [RR 0.85 (0.79–0.92)– 5.1% ARR and 0.91 (0.84–0.99)– 3.2% ARR, respectively] compared to lower doses. None of the differences between higher versus lower doses of BBs were significant; however, precision was low. Higher doses of these medications compared to lower doses increased the risk of discontinuation due to adverse events, hypotension, dizziness, and for ACEIs and ARBs, increased hyperkalemia and elevations in serum creatinine. Absolute increase in harms for adverse effects ranged from ~ 3 to 14%.

Conclusions

Higher doses of ACEIs and ARBs reduce the risk of HF worsening compared to lower doses, and higher doses of ARBs also reduce the risk of HF hospitalization but the evidence is sparse and imprecise. Higher doses increase the chance of adverse effects compared to lower doses. Evidence for BBs is inconclusive. These results support initially always starting at low doses of ACEIs/ARBs and only titrating the dose up if the patient tolerates dose increases.

Effect of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers on cardiovascular events in patients with heart failure: a meta-analysis of randomized controlled trials

Background

Heart failure (HF) remains a significant cause of morbidity and mortality. Multiple trials over the past several years have examined the effects of both angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) in the treatment of left ventricular dysfunction, both acutely after myocardial infarction and in chronic heart failure. Yet, there is still confusion regarding the relative efficacy of rennin-angiotensin-aldosterone system (RAAS) inhibition. Our study was conducted to assess efficacy of ACEIs and ARBs in reducing all-cause and cardiovascular mortality in heart failure patients.

Methods

We included randomized clinical trials compared ACEIs and ARBs treatment (any dose or type) with placebo treatment, no treatment, or other anti-HF drugs treatment, reporting cardiovascular or total mortality with an observation period of at least 12 months. Data sources included Pubmed, EMBASE, the Cochrane Central Register of Controlled Trials. Dichotomous outcome data from individual trials were analyzed using the risk ratio measure and its 95%CI with random-effects/ fixed-effects models. We performed meta-regression analyses to identify sources of heterogeneity. All-cause mortality and CV mortality were thought to be the main outcomes.

Results

A total of 47,662 subjects were included with a mean/median follow-up ranged from 12 weeks to 4.5 years. Of all 38 studies, 32 compared ACEIs with control therapy (included 13 arms that compared ACEIs with placebo, 10 arms in which the comparator was active treatment and 9 arms that compared ACEIs with ARBs), and six studies compared ARBs with placebo. ACEIs treatment in patients with HF reduced all-cause mortality to 11% (risk ratio (RR): 0.89, 95% confidence interval (CI): 0.83–0.96, p = 0.001) and the corresponding value for cardiovascular mortality was 14% (RR: 0.86, 95% CI: 0.78–0.94, p = 0.001). However, ARBs had no beneficial effect on reducing all-cause and cardiovascular mortality. In head-to-head analysis, ACEIs was not superior to ARBs for all-cause mortality and cardiovascular deaths.

Conclusions

In HF patients, ACEIs, but not ARBs reduced all-cause mortality and cardiovascular deaths. Thus, ACEIs should be considered as first-line therapy to limit excess mortality and morbidity in this population.

Electronic supplementary material

The online version of this article (10.1186/s12872-017-0686-z) contains supplementary material, which is available to authorized users.

Angiotensin II type 1 receptor blockade prevents alcoholic cardiomyopathy

BACKGROUND

Activation of the renin-angiotensin system (RAS) may contribute to the development of alcoholic cardiomyopathy. We evaluated the effect of angiotensin II (Ang II) type 1 receptor (AT1) blockade on the development of alcoholic cardiomyopathy.

METHODS AND RESULTS

We serially evaluated left ventricular (LV) and cardiomyocyte function and the RAS over 6 months in 3 groups of instrumented dogs. Eight animals received alcohol (once per day orally, providing 33% of total daily caloric intake); 6 received alcohol and irbesartan (5 mg.kg(-1).d(-1) PO); and 8 were controls. Compared with controls, alcohol ingestion caused sustained RAS activation with progressive increases in plasma levels of Ang II, renin activity, LV angiotensin-converting enzyme activity, and LV myocyte Ang II AT(1) receptor expression. The RAS activation was followed by a progressive fall in LV contractility (E(ES), alcohol-fed dogs 3.9+/-0.8 versus control dogs 8.1+/-1.0 mm Hg/mL); reductions in the peak velocity of myocyte shortening (78.9+/-5.1 versus 153.9+/-6.2 microm/s) and relengthening; and decreased peak systolic Ca2+ transient ([Ca2+]iT) and L-type Ca2+ current (I(Ca,L); P<0.05). Irbesartan prevented the alcohol-induced decreases in LV and myocyte contraction, relaxation, peak [Ca2+]iT, and I(Ca,L). With alcohol plus irbesartan, plasma Ang II, cardiac angiotensin-converting enzyme activity, and AT1 remained close to control values.

CONCLUSIONS

Chronic alcohol consumption produces RAS activation followed by progressive cardiac dysfunction. The cardiac dysfunction is prevented by AT1 receptor blockade.

Angiotensin II receptor blockers in congestive heart failure

The benefits of angiotensin-converting enzyme (ACE) inhibitors for the treatment of congestive heart failure (CHF) are well-established. A newer class of medications, angiotensin II receptor blockers (ARBs), may be a suitable replacement for ACE inhibitors as a result of a more complete inhibition of angiotensin II and better tolerability among patients. To examine the current literature on the efficacy and safety of ARBs in the setting of CHF, a Medline search was conducted of the English language literature for the years 1987 to 2005. Clinical trials that reported data on cardiac outcomes were reviewed. The earlier trials were direct ARB to ACE inhibitor comparisons (ELITE I and ELITE II). These studies indicated that ARBs do not confer an improvement in cardiac outcomes over ACE inhibitors. RESOLVD, Val-HeFT, and the 3 separate trials of the CHARM program investigated the addition of an ARB to standard therapy. The RESOLVD trial showed no significant differences in clinical events among ACE inhibitor, ARB, and their combination. Although no mortality benefit was evident in the Val-HeFT trial, a substantial reduction in CHF rehospitalizations was reported among patients who were not receiving ACE inhibitor therapy. The CHARM-Overall program demonstrated a significant benefit in cardiovascular death and hospital admissions for CHF with the addition of ARB to standard therapy, a benefit that was more pronounced in patients with depressed left ventricular ejection fraction. In the setting of CHF, rates of cardiac outcomes do not differ substantially between ARBs and ACE inhibitors. However, their combination may improve outcomes for patients with CHF.

Angiotensin Receptor Blockers in Congestive Heart Failure

Heart failure results in neurohormonal activation of which the renin-angiotensin-aldosterone system (RAS) is the main mediator. Activation of this system leads to the production of angiotensin II (ATII), which leads to multiple adverse short-term and long-term effects, including hemodynamic dysfunction, renal dysfunction, inflammation, and cardiac remodeling. Angiotensin-converting enzyme inhibitors (ACEIs) exert favorable effects in congestive heart failure (CHF) by inhibiting the production of ATII. It has been shown that ACEIs may not be able to suppress the production of ATII completely because there are RAS-independent mechanisms of ATII production. Hence, it was thought that angiotensin receptor blockers (ARBs) might be more useful in CHF because they directly block the ATII receptors. Many studies have been done to evaluate the role of ARBs in CHF. We reviewed these studies and have attempted to define the place and ARBs in the therapy for CHF.

AT1 Receptor Blockade Prevents Cardiac Dysfunction after Myocardial Infarction in Rats

Myocardial infarction (MI) can induce severe alterations of contractile function that can, in turn, lead to heart failure. In a previous study, we have demonstrated that TNF-alpha was involved in cardiac contractile dysfunction 7 days after coronary artery ligation in rats. Since Angiotensin II type 1 (AT1) receptor can be involved in TNF-alpha production, we have investigated whether early short-term treatment with irbesartan, an AT1 receptor blocker, is able to limit TNF-alpha production within the heart and to improve cardiac function and geometry following MI in rats. Male Wistar rats were subjected to permanent coronary artery ligation and received either a placebo or irbesartan (50 mg/kg/day) per os daily from day 3 to day 6 after surgery. On day 7, cardiac TNF-alpha was significantly reduced in MI rats receiving irbesartan (p < 0.05). Moreover, irbesartan improved residual LV end-diastolic pressure under both basal conditions and after volume overload (p < 0.01). In addition, a significant leftward shift of the pressure-volume curve in the irbesartan-treated group was found versus placebo. Finally, infarct expansion index was also significantly improved by irbesartan (p < 0.01). In conclusion, early, short-term AT1 receptor blockade limits post-infarct cardiac TNF-alpha production and diminishes myocardial alterations observed 7 days after MI in the rat.

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.

Irbesartan inhibits human T-lymphocyte activation through downregulation of activator protein-1

1 Irbesartan is a promising antihypertensive drug with beneficial effects on atherosclerotic processes. In the progression of atherosclerosis, human T-lymphocytes play an important role, but it is not yet known how irbesartan modulates human T-lymphocytes activation. To gain insight into the mechanisms by which irbesartan acts, we investigated its effects on human T-lymphocytes. 2 Primary human T-lymphocytes were isolated from whole blood. Cytokines were determined by ELISA. Activator protein-1 (AP-1) and related protein activities were determined by electrophoretic mobility shift assays, kinase assays, Western blotting and transfection assays. 3 Irbesartan inhibited the production of both tumor necrosis factor-alpha and interferon-gamma by activated T-cells, especially at therapeutic concentrations. Further investigation at the molecular level indicated that the inhibition of activated human T-lymphocytes specifically correlated with the downregulation of AP-1 DNA-binding activity. In the Jurkat T-cell line, irbesartan also inhibited AP-1 transcriptional activity. Finally, we revealed that irbesartan is unique in its ability to inhibit the activation of both c-Jun NH2-terminal protein kinase and p38 MAPK. 4 Our studies show that irbesartan may modulate inflammation-based atherosclerotic diseases through a cell-mediated mechanism involving suppression of human T-lymphocytes activation via downregulation of AP-1 activity.

Angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers: what we know and current controversies

A little more than a decade ago, management of heart failure was changed forever when a number of randomized clinical trials confirmed that a class of drugs, angiotensin-converting enzyme (ACE) inhibitors, could improve survival in patients with heart failure. The recognition that blockade of one of the neurohumoral systems activated in heart failure could improve outcomes prompted widespread testing of other neurohumoral blockers, such as beta-adrenergic blocking agents, aldosterone antagonists, and most recently, angiotensin II type 1 receptor blockers (ARBs) for the treatment of heart failure. This article describes what is known about the use of ACE inhibitors and ARBs in the management of heart failure and presents the current controversies surrounding the use of these agents.

Angiotensin antagonism in patients with heart failure: ACE inhibitors, angiotensin receptor antagonists or both?

Chronic heart failure (CHF) is a major cause of morbidity and mortality in western society. It is now widely accepted that the renin-angiotensin-aldosterone system (RAAS) and, in particular, angiotensin II (A-II) play a key role in the pathophysiology of CHF. Large-scale clinical trials have demonstrated that inhibitors of angiotensin-converting enzyme (ACE), the principal enzyme responsible for A-II production, improve symptoms and survival in patients with CHF. This enzyme is also responsible for the breakdown of the vasodilator hormone bradykinin. Administration of ACE inhibitors is associated with increased plasma bradykinin levels and this is thought to contribute to the vascular changes associated with ACE inhibitor therapy. However, RAAS inhibition with ACE inhibitors remains incomplete because ACE inhibitors do not block the non-ACE-mediated conversion of angiotensin I to A-II. Angiotensin receptor antagonists (angiotensin receptor blockers; ARBs) antagonize the action of A-II at the A-II type 1 (AT(1)) receptor, whilst allowing the potentially beneficial actions of A-II mediated via the A-II type 2 (AT(2)) receptor. Evidence that the clinical benefit demonstrated with ACE inhibitors in patients with CHF may extend to ARBs has only emerged recently. Combination therapy with both an ACE inhibitor and an ARB has a number of potential advantages and has been investigated in several large-scale clinical trials recently. In patients with CHF, first-line therapy should include an ACE inhibitor and a beta-adrenoceptor antagonist. The addition of an ARB provides symptomatic relief but has not been shown to improve survival. Where an ACE inhibitor is not tolerated, treatment with an ARB would seem an appropriate alternative. There is insufficient data to support the routine use of ARBs as first-line therapy in the management of CHF.

Angiotensin II receptor blockers in heart failure

Heart failure remains a significant cause of morbidity and mortality, despite major advances in therapy. Angiotensin II, the principal mediator of the renin-angiotensin system, exerts both short-term (e.g., hemodynamic, renal) and long-term (e.g., inflammation, cardiac remodeling) effects in the pathophysiology of cardiovascular disease. The effects of angiotensin II appear to be more completely inhibited by angiotensin II receptor blockers (ARBs), which act at the subtype 1 receptor level, than by angiotensin-converting enzyme (ACE) inhibitors because pathways other than that of ACE contribute to the generation of angiotensin II. Evidence demonstrates that ARBs, when added to conventional treatment for patients with heart failure, are associated with a reduction in morbidity and mortality as well as an improvement in quality of life. Clinical trials of ARB therapy indicate that these agents are generally well tolerated, both alone and in combination with other neurohormonal inhibitors. The current role of ARBs in heart failure is as an alternative for patients who cannot tolerate therapy with an ACE inhibitor. A number of ongoing clinical studies are likely to further define or expand the role of ARBs in the treatment of cardiovascular disease.

The role of angiotensin II receptor blockers in the treatment of heart failure patients

Evidence from large, randomized, controlled clinical trials supports the use of angiotensin-converting enzyme (ACE) inhibitors, beta blockers, and spironolactone to reduce mortality and morbidity. Despite these effective therapies, event rates related to heart failure remain high. Although ACE inhibitors reduce angiotensin II production, they do not fully suppress the increased angiotensin II production in heart failure. Angiotensin II receptor blockers (ARBs) directly block the effect of angiotensin II, derived from any source, at the receptor level and have the potential to be as effective or even more effective than ACE inhibitors. The results of a number of clinical studies have demonstrated ARBs are effective and well tolerated. However, no studies have demonstrated a convincing decrease in mortality with ARB use, although a decrease has been observed for heart failure hospitalization. The results from further studies are awaited to clarify the role of ARBs in the treatment of heart failure.

Angiotensin II receptor antagonists in chronic heart failure: where do they fit?

Heart failure is a common and disabling condition with a dismal prognosis. Inhibition of the renin-angiotensin-aldosterone system (RAAS) with angiotensin converting enzyme (ACE) inhibitors has proven to be a valuable therapeutic strategy in this condition, with well-proven morbidity and mortality benefits. Nonetheless, ACE inhibitors provide incomplete blockade of the RAAS and also inhibit the degradation of bradykinin. Although increased levels of bradykinin may have haemodynamic advantages by contributing to vasodilatation, they may also be largely responsible for some of the adverse effects of ACE inhibitors. Angiotensin II (Ang II) receptor antagonists offer more complete blockade of the RAAS without the potentiation of bradykinin, and it was therefore hoped that they would provide even greater benefits for patients with heart failure. So far, much of the initial promise of the Ang II receptor antagonists in heart failure has not been realised. There has been no conclusive demonstration of their superiority to ACE inhibitors in their effects on morbidity and mortality, and their equivalence to ACE inhibitors has not been proven. The Ang II receptor antagonists have, however, proven to be better tolerated than ACE inhibitors and they are therefore likely to be a reasonable alternative for those patients with heart failure who cannot tolerate ACE inhibition. Recent evidence has indicated that the Ang II type 1 receptor antagonist valsartan is of value when used in patients already receiving either an ACE inhibitor or a beta-blocker, but has also suggested that giving all three drugs together is deleterious. Further evidence about the value of Ang II receptor antagonists in heart failure may be provided by further studies, of which several are currently ongoing.

Angiotensin II Type 1 receptor antagonists in chronic heart failure

Angiotensin II Type 1 receptor antagonists share most but not all of their pharmacological actions with angiotensin-converting enzyme inhibitors. The latter belong to standard heart failure therapy, with proven benefit in terms of morbidity and mortality. Promising data have been provided for angiotensin II Type 1 receptor antagonists in experimental models of heart failure. In patients with hypertension and those with diabetic nephropathy, favourable results have been observed with regards to blood pressure control, reversibility of structural changes or prevention of progression of disease. The currently available clinical trials in heart failure patients with angiotensin II Type 1 receptor antagonists suggest that they may be equivalent to angiotensin-converting enzyme inhibitors, but superiority has not been proven. There is no doubt about their effectiveness with regards to symptoms; however, their effect on hospitalisation and mortality is not unequivocally demonstrated. Further trials are warranted, particularly to define their role in comparison with and in addition to angiotensin-converting enzyme inhibitors and to further characterise heart failure patient populations who derive benefit from angiotensin II Type 1 receptor blockers above and beyond angiotensin-converting enzyme inhibitors, beta-blockers and spironolactone.

The Evolving Role of Angiotensin Receptor Blockers in Heart Failure

This continuing feature will update readers on recent developments in cardiovascular pharmacotherapy. Cardiovascular disease remains the number one killer in the US, and more clinical outcome trials have been conducted in cardiology than in any other field of medicine. Given this rapidly expanding knowledge base, pharmacists can have a significant impact on the prevention and treatment of cardiovascular disease—if they keep current with developments in drug therapy.

Angiotensin type-1 receptor blockers in heart failure

Chronic heart failure is a common condition with a poor prognosis, usually associated with poor exercise tolerance and debilitating symptoms despite optimal modern therapy. Standard therapy includes diuretics, digoxin, angiotensin-converting enzyme inhibitors (ACEIs) and beta-blockers. Despite this, many patients remain symptomatic, and interest is high as to whether the angiotensin receptor blockers (ARBs) would offer further advantage to a patient already receiving quadruple therapy. In addition, some patients are intolerant of ACEIs, and for this group the ARBs seem a logical choice. This article reviews the evidence for the use of ARBs as a class in heart failure concentrating on clinical recommendations and clinical needs and evidence rather than purely on statistical issues of significance in trials. The trials to date have demonstrated clearly similar hemodynamic effects to those seen with ACEIs and variety of ancillary benefits such as improvements in endothelial function, anti-thrombotic effects, and effects on neurohormonal inhibition. There is consistent evidence of a preservation of exercise tolerance when patients with heart failure are crossed over from stable ACEI therapy, and when added to ACEIs exercise tolerance appears to increase with ARBs. In terms of major outcomes, the two largest trials, Elite-II and Val-Heft, demonstrate that angiotensin receptor blockers probably have a clinical role in improving mortality and morbidity as an alternative to ACEIs in those patients unable to tolerate these agents, which remain, however, the first choice in unselected patients with heart failure. There is a worrying suggestion of a negative interaction when ARBs are added to beta-blockers, which is a reason for caution in using the ARBs, not a reason not to use beta-blockers.

Formulating clinical strategies for angiotensin antagonism: a review of preclinical and clinical studies

Extensive animal studies and a growing number of human clinical trials have now definitively demonstrated the central role of the renin-angiotensin-aldosterone system in the expression and modulation of cardiovascular disease. In contrast to the original hypothesis, the benefits of angiotensin antagonism do not emanate from the antihypertensive effect alone. Subsequent extensive investigations of angiotensin blockade suggest that the benefits of this approach may also result from the pharmacologic alteration of endothelial cell function and the ensuing changes in the biology of the vasculature. The more recent availability of direct antagonists of the AT(1) angiotensin receptor has introduced an element of doubt into this realm of clinical decision making. The receptor antagonists and the more widely studied converting-enzyme inhibitors share many endpoint attributes. Nevertheless, the partially overlapping mechanisms of action for the two classes of angiotensin antagonists confer distinct pharmacologic properties, including side effect profiles, mechanisms of action, and theoretic salutary effects upon the expression of cardiovascular disease. The current review will attempt to contrast the biology of angiotensin converting-enzyme inhibition with angiotensin II receptor antagonism. A discussion of the differential effects of these drug classes on endothelial cell function and on the modulation of vascular disease will be utilized to provide a theoretic framework for clinical decision making and therapeutics.

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.

Angiotensin receptor blockers: evidence for preserving target organs

Hypertension is a major problem throughout the developed world. Although current antihypertensive treatment regimens reduce morbidity and mortality, patients are often noncompliant, and medications may not completely normalize blood pressure. As a result, current therapy frequently does not prevent or reverse the cardiovascular remodeling that often occurs when blood pressure is chronically elevated. Blockade of the renin-angiotensin system (RAS) is effective in controlling hypertension and treating congestive heart failure. Both angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) inhibit the activity of the RAS, but these two classes of antihypertensive medications have different mechanisms of action and different pharmacologic profiles. Angiotensin-converting enzyme inhibitors block a single pathway in the production of angiotensin II (Ang II). In addition, angiotensin I is not the only substrate for ACE. The ACE inhibitors also block the degradation of bradykinin that may have potential benefits in cardiovascular disease. Bradykinin is, however, the presumed cause of cough associated with ACE inhibitor therapy. Data from clinical trials on ACE inhibitors serve to support the involvement of the RAS in the development of cardiovascular disease. Angiotensin receptor blockers act distally in the RAS to block the Ang II type 1 (AT1) receptor selectively. Thus, ARBs are more specific agents and avoid many side effects. Experimental and clinical trials have documented the efficacy of ARBs in preserving target-organ function and reversing cardiovascular remodeling. In some instances, maximal benefit may be obtained with Ang II blockade using both ARBs and ACE inhibitors. This review describes clinical trials that document the efficacy of ARBs in protecting the myocardium, blood vessels, and renal vasculature.

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.

Perioperative Treatment of Congestive Heart Failure

Congestive heart failure is a common disease that affects 5 million people and will continue to increase in prevalence as the population ages. Estimates of its prevalence in patients presenting for vascular surgery range up to 50%. It has been consistently shown to be associated with increased mortal ity after vascular surgery. The anesthesiologist's contact with this disease entity will increase as well. Little has changed in the treatment of this disease until recently. Many new developments have occurred in the pathophysiology and the treatment of this age-old disease. This article re views developments in the pathophysiology, which have resulted in a new understanding and a complete revision of the recommendations for the treatment of heart failure as well as some modalities that hold promise for the future.

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.

Irbesartan does not affect the pharmacokinetics of simvastatin in healthy subjects

This open-label, single-dose, crossover study was conducted to assess the effect of irbesartan on the pharmacokinetics of total simvastatin acid in 14 healthy subjects. Subjects were randomized to receive one simvastatin 40 mg tablet or one simvastatin 40 mg tablet + one irbesartan 300 mg tablet. Subjects were crossed over to the other treatment after a 7- to 10-day washout period. Serum samples were collected at specified times before and over a 24-hour period after dosing. Safety was assessed by monitoring vital signs, laboratory tests, and adverse events. Irbesartan did not exhibit a clinically significant effect on the peak serum concentration and area under the concentration versus time curve to infinity (AUC0-infinity) of total simvastatin acid. The mean AUC0-infinity of total simvastatin acid was 74.55 ng x h/mL when simvastatin was given alone and 67.55 ng x h/mL when simvastatin and irbesartan were given concomitantly. The time to peak serum concentration for both treatments was 3 hours. No serious adverse events occurred during the study, and both agents were well tolerated. In summary, irbesartan had no significant effect on the single-dose pharmacokinetics of total simvastatin acid.

Pharmacotherapy of systolic heart failure: a review of recent literature and practical applications

Since the publication of the Agency for Health Care Policy and Research Guidelines for treatment of heart failure, a number of new agents have been investigated for this indication. beta-Blockers have now been shown to improve outcomes in mild to moderate heart failure when added to standard therapy. Angiotensin II receptor antagonists have also been investigated and show promise. In general, calcium channel blockers are second- or third-line agents in patients refractory to other therapy. Investigational agents including spironolactone may also hold promise for future therapy.

Long-term angiotensin II type 1 receptor blockade with fonsartan doubles lifespan of hypertensive rats

In this study, we investigated the outcome of lifelong treatment with the angiotensin II type 1 receptor (AT(1)) blocker fonsartan (HR 720) in young stroke-prone spontaneously hypertensive rats (SHR-SP). In addition to the primary end point, lifespan, and to determine the mechanisms involved in the treatment-induced effects, parameters such as left ventricular hypertrophy, cardiac function/metabolism, endothelial function, and the expression/activity of endothelial nitric oxide synthase and of angiotensin-converting enzyme (ACE) were also investigated. Ninety 1-month-old SHR-SP were allotted to 2 groups and treated via drinking water with an antihypertensive dose of fonsartan (10 mg. kg(-1). d(-1)) or placebo. Fonsartan doubled the lifespan to 30 months in SHR-SP, which was comparable to the lifespan of normotensive Wistar-Kyoto rats. After 15 months, a time when approximately 80% of the placebo group had died, left ventricular hypertrophy was completely prevented in fonsartan-treated animals. Furthermore, cardiac function and metabolism as well as endothelial function were significantly improved. These effects were correlated with increased endothelial nitric oxide synthase expression in the heart and carotid artery and with markedly decreased tissue ACE expression/activities. Lifespan extension and cardiovascular protection by long-term AT(1) blockade with fonsartan led to similar beneficial effects, as observed with long-term ACE inhibition.

The role of angiotensin receptor blockers in heart failure

The effectiveness of ACE inhibitors in reducing morbidity and mortality in patients with heart failure is largely attributable to their suppression of angiotensin II production. Despite chronic therapy with ACE inhibitors, angiotensin II levels may be incompletely suppressed and contribute to the high mortality of patients with heart failure. Recently, angiotensin receptor blockers, which block the effects rather than the production of angiotensin II, have become available. Angiotensin receptor blockers have been evaluated as both monotherapy and in combination with ACE inhibitors. In short term studies, angiotensin receptor blocker monotherapy appears to share many of the hemodynamic and clinical features of ACE inhibitors. In a long-term study, the Losartan Heart Failure Survival Study, angiotensin receptor blockers failed to demonstrate any beneficial effect over that seen with ACE inhibitors. The addition of an angiotensin receptor blocker to an ACE inhibitor appears to exert favorable short term hemodynamic, clinical, and neurohormonal effects. Four ongoing trials, Valsartan Heart Failure Trial, Candesartan in Heart Failure Assessment of Reduction in Mortality and Morbidity, Optimal Therapy in Myocardial Infarction with Angiotensin II Antagonist Losartan study, and Valsartan In Acute Myocardial Infarction study, are evaluating the role of angiotensin receptor blockers either alone or in combination with ACE inhibitors in the management of left ventricular dysfunction. (c)2000 by CHF, Inc.

Angiotensin II receptor antagonists

Blockade of the renin-angiotensin system began as a way of studying the pathogenesis of cardiovascular disease with specific pharmacological probes. Oral activity, achieved by shortening the original peptide structures, transformed the probes into therapeutic agents, the angiotensin-converting enzyme (ACE) inhibitors. However, ACE is a non-specific target for blocking the renin-angiotensin enzymatic cascade. The availability of orally active drugs turned ACE inhibition into a therapeutic breakthrough but more specific blockade always seemed desirable. This goal has now been achieved with the orally active angiotensin II receptor antagonists; six are on the market and more are under development. This new class of drugs is equal in efficacy to ACE inhibitors, at least in hypertensive patients. Trials now underway will demonstrate whether angiotensin II receptor antagonists can prevent target-organ damage and reduce cardiovascular morbidity and mortality. If they do, these compounds might one day replace ACE inhibitors.

Angiotensin receptor blockers in heart failure after the ELITE II trial

Specific blockers of the angiotensin type1 receptor, angiotensin receptor blockers (ARBs), have been introduced as an alternative to angiotensin-converting enzyme inhibitors (ACEi) for the treatment of heart failure. In comparison with ACEi, ARBs are better tolerated and have similar effects on haemodynamics, neurohormones and exercise capacity. Early studies have suggested that ARBs might have a superior effect on mortality. However, the first outcome trial, ELITE II (Losartan Heart Failure Survival Study), did not show any significant difference between losartan and captopril in terms of mortality or morbidity. This commentary outlines the role of ARBs in the treatment of heart failure.