The hemodynamic and neurohormonal effects of low doses of tezosentan (an endothelin A/B receptor antagonist) in patients with acute heart failure

Vasodilators for Acute Heart Failure - A Systematic Review with Meta-Analysis

BACKGROUND

Acute heart failure is a public health concern. This study systematically reviewed randomized clinical trials (RCTs) to evaluate vasodilators in acute heart failure.

METHODS

The search was conducted across the databases of Medline, Embase, Latin American and the Caribbean Literature on Health Sciences, Web of Science, and the Cochrane Central Register of Controlled Trials. Inclusion criteria consisted of RCTs that compared vasodilators versus standard care, placebo, or cointerventions. The primary outcome was all-cause mortality; secondary outcomes were serious adverse events (SAEs), tracheal intubation, and length of hospital stay. Risk of bias was assessed in all trials.

RESULTS

The study included 46 RCTs that enrolled 28,374 patients with acute heart failure. Vasodilators did not reduce the risk of all-cause mortality (risk ratio, 0.95; 95% confidence interval [CI], 0.87 to 1.04; I2=9.51%; P=0.26). No evidence of a difference was seen in the risk of SAEs (risk ratio, 1.01; 95% CI, 0.97 to 1.05; I2=0.94%) or length of hospital stay (mean difference, -0.10; 95% CI, -0.28 to 0.08; I2=69.84%). Vasodilator use was associated with a lower risk of tracheal intubation (risk ratio, 0.54; 95% CI, 0.30 to 0.99; I2=51.96%) compared with no receipt of vasodilators.

CONCLUSIONS

In this systematic review with meta-analysis of patients with acute heart failure, vasodilators did not reduce all-cause mortality.

Efficacy of pharmacologic therapies in patients with acute heart failure: A network meta-analysis

Background: A network meta-analysis (NMA) of the current recommended drugs for the treatment of acute heart failure (AHF), was performed to compare the relative efficacy.

Methods: We used PubMed, EMBASE, Cochrane Clinical Trials Register, and Web of Science systems to search studies of randomized controlled trials (RCT) for the treatment of AHF recommended by the guidelines and expert consensus until 1 December 2020. The primary outcome was all-cause mortality within 30 days. The secondary outcomes included 30-days all-cause rehospitalization, rates of HF-related rehospitalization, rates of adverse events, and rates of serious adverse events. A Bayesian NMA based on random effects model was performed.

Results: After screening 14,888 citations, 23 RCTs (17,097 patients) were included, focusing on nesiritide, placebo, serelaxin, rhANP, omecamtiv mecarbil, tezosentan, KW-3902, conivaptan, tolvaptan, TRV027, chlorothiazide, metolazone, ularitide, relaxin, and rolofylline. Omecamtiv mecarbil had significantly lower all-cause mortality rates than the placebo (odds ratio 0.04, 0.01–0.22), rhANP (odds ratio 0.03, 0–0.40), serelaxin (odds ratio 0.05, 0.01–0.38), tezosentan (odds ratio 0.04, 0–0.22), tolvaptan (odds ratio 0.04, 0.01–0.30), and TRV027 (odds ratio 0.03, 0–0.36). No drug was superior to the other drugs for the secondary outcomes and safety outcomes.

Conclusion: No drug was superior to the other drugs for the secondary outcomes and safety outcomes. Current drugs for AHF show similar efficacy and safety.

Effects of clazosentan on cerebral vasospasm-related morbidity and all-cause mortality after aneurysmal subarachnoid hemorrhage: two randomized phase 3 trials in Japanese patients

OBJECTIVE

Clazosentan has been investigated globally for the prevention of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (aSAH). The authors evaluated its effects on vasospasm-related morbidity and all-cause mortality following aSAH in Japanese patients.

METHODS

Two similar double-blind, placebo-controlled phase 3 studies were conducted in 57 Japanese centers in patients with aSAH, after aneurysms were secured by endovascular coiling in one study and surgical clipping in the other. In each study, patients were randomly administered intravenous clazosentan (10 mg/hr) or placebo (1:1) starting within 48 hours of aSAH and for up to 15 days after aSAH. Stratified randomization based on World Federation of Neurosurgical Societies grade was performed using a centralized interactive web response system. Vasospasm-related morbidity and all-cause mortality within 6 weeks post-aSAH, including new cerebral infarcts and delayed ischemic neurological deficits as well as all-cause mortality, were the first primary endpoint in each study. The second primary endpoint was all-cause morbidity (new cerebral infarct or delayed ischemic neurological deficit from any causes) and all-cause mortality (all-cause morbidity/mortality) within 6 weeks post-aSAH. The incidence of individual components of the primary morbidity/mortality endpoints within 6 weeks and patient outcome at 12 weeks post-aSAH (including the modified Rankin Scale scores) were also evaluated. The above analyses were also performed in the population pooled from both studies.

RESULTS

In each study, 221 patients were randomized and 220 were included in the full analysis set of the primary analysis (109 in each clazosentan group, 111 in each placebo group). Clazosentan significantly reduced the incidence of vasospasm-related morbidity and all-cause mortality after aneurysm coiling (from 28.8% to 13.6%; relative risk reduction 53%; 95% CI 17%-73%) and after clipping (from 39.6% to 16.2%; relative risk reduction 59%; 95% CI 33%-75%). All-cause morbidity/mortality and poor outcome (dichotomized modified Rankin Scale scores) were significantly reduced by clazosentan after preplanned study pooling. Treatment-emergent adverse events were similar to those reported previously.

CONCLUSIONS

Clazosentan significantly reduced the combined incidence of vasospasm-related morbidity and all-cause mortality post-aSAH with no unexpected safety findings. Clinical trial registration nos.: JapicCTI-163368 and JapicCTI-163369 (https://www.clinicaltrials.jp).

Dyspnea Measurement in Acute Heart Failure: A Systematic Review and Evidence Map of Randomized Controlled Trials

Background: Dyspnea is the most common presenting symptom among patients hospitalized for acute heart failure (AHF). Dyspnea relief constitutes a clinically relevant therapeutic target and endpoint for clinical trials and regulatory approval. However, there have been no widely accepted dyspnea measurement standards in AHF. By systematic review and mapping the current evidence of the applied scales, timing, and results of measurement, we hope to provide some new insights and recommendations for dyspnea measurement. Methods: PubMed, Embase, Cochrane Library, and Web of Science were searched from inception until August 27, 2020. Randomized controlled trials (RCTs) with dyspnea severity measured as the endpoint in patients with AHF were included. Results: Out of a total of 63 studies, 28 had dyspnea as the primary endpoint. The Likert scale (34, 54%) and visual analog scale (VAS) (22, 35%) were most widely used for dyspnea assessment. Among the 43 studies with detailed results, dyspnea was assessed most frequently on days 1, 2, 3, and 6 h after randomization or drug administration. Compared with control groups, better dyspnea relief was observed in the experimental groups in 21 studies. Only four studies that assessed tolvaptan compared with control on the proportion of dyspnea improvement met the criteria for meta-analyses, which did not indicate beneficial effect of dyspnea improvement on day 1 (RR: 1.16; 95% CI: 0.99-1.37; p = 0.07; I ² = 61%). Conclusion: The applied scales, analytical approaches, and timing of measurement are in diversity, which has impeded the comprehensive evaluation of clinical efficacy of potential therapies managing dyspnea in patients with AHF. Developing a more general measurement tool established on the unified unidimensional scales, standardized operation protocol to record the continuation, and clinically significant difference of dyspnea variation may be a promising approach. In addition, to evaluate the effect of experimental therapies on dyspnea more precisely, the screening time and blinded assessment are factors that need to be considered.

Randomized double-blind clinical studies of ularitide and other vasoactive substances in acute decompensated heart failure: a systematic review and meta-analysis

AIMS

Acute decompensated heart failure (ADHF) has a poor prognosis and limited treatment options. No direct comparisons between ularitide-a synthetic natriuretic peptide being evaluated in ADHF-and other vasoactive substances are available. The aim of this meta-analysis was to determine haemodynamic effect sizes from randomized double-blind trials in ADHF.

METHODS AND RESULTS

Eligible studies enrolled patients with ADHF requiring hospitalization and haemodynamic monitoring. Patients received 24-48 h of infusion with a vasoactive substance or comparator. Primary outcome measure was pulmonary artery wedge pressure (PAWP). Treatment effects were quantified as changes from baseline using mean differences between study drug and comparator. Results were analysed using random-effects (primary analysis) and fixed-effects meta-analyses. Twelve randomized, double-blind studies were identified with data after 3, 6, and 24 h of treatment (n = 622, 644, and 644, respectively). At 6 h, significant PAWP benefits for ularitide over placebo were seen (Hedges' g effect size, -0.979; P < 0.0001). On meta-analysis, treatment difference between ularitide and pooled other agents was statistically significant (-0.501; P = 0.0303). Effect sizes were numerically higher with ularitide than other treatments at 3 and 24 h. After 6 h, a significant difference in effect size between ularitide and all other treatments was observed for right atrial pressure (Hedges' g, -0.797 for ularitide and -0.304 for other treatments; P = 0.0274).

CONCLUSIONS

After 6 h, ularitide demonstrated high effect sizes for PAWP and right atrial pressure. Improvements in these parameters were greater with ularitide vs. pooled data for other vasoactive drugs.

An integrative review of the literature on in-hospital worsening heart failure

A subset of patients hospitalized for acute exacerbation of chronic heart failure develop in-hospital worsening heart failure. The objective of this paper is to present an integrative review of in-hospital worsening heart failure, including definitions, incidence, prevalence, mechanisms, treatments, outcomes, and early identification by providers. A search of electronic databases was conducted from January 2000-August 2017 using multiple search terms. Papers were reviewed for relevance; retained papers were abstracted and data were reported in a narrative synthesis. Twenty papers were selected. Many papers were observational data from in-hospital events that occurred during research trials. There was great variability in in-hospital worsening heart failure definition, incidence, prevalence, and treatments offered. Despite rescue therapies, in-hospital worsening heart failure was associated with increased risk for longer hospital stays, higher readmission rates, and death. To date, there are no therapies that target the underlying mechanisms or minimize its occurrence.

How to tackle congestion in acute heart failure

Acute heart failure is a common complication of chronic heart failure and is associated with a high risk for subsequent mortality and morbidity. In 90% of case acute heart failure is the resultant of congestion, a manifestation of fluid build-up due to increased filling pressures. As residual congestion at discharge following an acute heart failure episodes is one of the strongest predictors of poor outcome, the goal of therapy should be to resolve congestion completely. Important to comprehend is that increased cardiovascular filling pressures are not solely the resultant of intravascular volume excess but can also be induced by a decreased venous capacitance. This review article focusses on the pathophysiology, diagnoses, and treatment of congestion in acute heart failure. A clear distinction is made between states of volume overload (intravascular volume excess) or volume redistribution (decreased venous capacitance) contributing to congestion in acute heart failure.

Clinical and Hemodynamic Effects of Endothelin Receptor Antagonists in Patients With Heart Failure

The clinical benefit of endothelin receptor antagonists (ERA) for the management of heart failure (HF) remains controversial. To examine this question, we performed a meta-analysis of randomized controlled trials (RCTs) to investigate the clinical and hemodynamic effects of ERA in HF patients.We searched the PubMed, Medline, Embase, and Cochrane Library from inception to March 20, 2016 to identify the pertinent studies. Risk ratio (RR) and weighted mean difference (WMD) were calculated using a fixed or random effect model.A total of 15 RCTs with 3,624 HF patients were included. Compared with control groups, ERA might not improve the mortality (RR 1.12, 95%CI 0.81 to 1.54, P = 0.51) or incidence of worsening HF or cardiovascular events (WHF/ CVE) (RR 1.06, 95%CI 0.94 to 1.19, P = 0.35) in HF patients. Subgroup analysis also suggested that neither nonselective nor selective ERAs had an impact on mortality and WHF/CVE. However, the hemodynamic variables of HF patients, including cardiac index (WMD 0.32, 95%CI 0.22 to 0.43, P < 0.01), pulmonary capillary wedge pressure (WMD -3.10, 95%CI -3.99 to -2.20, P < 0.01), mean pulmonary arterial pressure (WMD -4.42, 95%CI -5.50 to -3.33, P < 0.01), systemic vascular resistance (WMD -276.35, 95%CI -399.62 to -153.09, P < 0.01), and pulmonary vascular resistance (WMD -69.42, 95%CI -105.33 to -33.52, P < 0.01) were significantly improved by ERA.In conclusion, this meta-analysis suggests that ERA therapy could effectively improve cardiac output and pulmonary and systemic hemodynamics, but with less benefit to the clinical outcomes of HF patients.

Similar hemodynamic decongestion with vasodilators and inotropes: systematic review, meta-analysis, and meta-regression of 35 studies on acute heart failure

BACKGROUND

Acute heart failure (AHF) with reduced left-ventricular ejection fraction (LVEF) is often a biventricular congested state. The comparative effect of vasodilators and inotropes on the right- and/or left-sided congestion is unknown.

METHODS AND RESULTS

A systematic review, meta-analysis, and meta-regression of AHF studies using pulmonary artery catheter were performed using PubMed, Embase, and Cochrane library. Data from 35 studies, including 3016 patients, were studied. Included patients had a weighted mean age of 60 years, left-ventricular ejection fraction (LVEF) of 24 %, and plasma B-type natriuretic peptide (BNP) of 892 pg/ml. Both the left- and right-ventricular filling pressures were elevated: weighted mean pulmonary artery wedge pressure (PAWP) was 25 mmHg (range 17-31 mmHg) and right atrial pressure (RAP) 12 mmHg (range 7-18 mmHg). Vasodilators and inotropes had similar beneficial effects on PAWP [-6.3 mmHg (95 % CI -7.4 to -5.2 mmHg) and -5.8 mmHg (95 % CI -7.6 to -4.0 mmHg), respectively] and RAP [-2.9 mmHg (95 % CI -3.8 to -2.1 mmHg) and -2.8 mmHg (95 % CI -3.8 to -1.7 mmHg), respectively]. Among inotropes, inodilators, such as levosimendan, have greater beneficial effect on the left-ventricular filling pressure than dobutamine. Drug-induced improvement of PAWP tightly paralleled that of RAP with all studied drugs (r ² = 0.90, p < 0.001). Vasodilators and inotropes had no short-term effect of renal function.

CONCLUSION

The left- and right-sided filling pressures are similarly improved by vasodilators or inotropes, in AHF with reduced LVEF.

The Impact of Worsening Heart Failure in the United States

In-hospital worsening heart failure represents a clinical scenario wherein a patient hospitalized for acute heart failure experiences a worsening of their condition, requiring escalation of therapy. Worsening heart failure is associated with worse in-hospital and postdischarge outcomes. Worsening heart failure is increasingly being used as an endpoint or combined endpoint in clinical trials, as it is unique to episodes of acute heart failure and captures an important event during the inpatient course. While prediction models have been developed to identify worsening heart failure, there are no known FDA-approved medications associated with decreased worsening heart failure. Continued study is warranted.

Editor's Choice-Recent therapeutic trials on fluid removal and vasodilation in acute heart failure

Recent therapeutic trials regarding the management of acute heart failure (AHF) failed to demonstrate the efficacy of newer therapeutic modalities and agents. Low- versus high-dose and continuous administration of furosemide were shown not to matter. Ultrafiltration was not found to be more efficacious than sophisticated diuretic therapy including dose-adjusted intravenous furosemide and metolazone. Dopamine and nesiritide were not shown to be superior to current therapy. Tezosentan and tovalptan had no effect on mortality. The development of rolofylline was terminated due to adverse effect (seizures). Lastly, preliminary experience with serelaxin indicates a mortality improvement at six months that remains to be confirmed. The disappointing findings of these recent trials may reflect the lack of efficacy of newer therapeutic modalities and agents. Alternatively the disappointing findings of these recent trials may be in part due to methodological issues. The AHF syndrome is complex with many clinical phenotypes. Failure to match clinical phenotypes and therapeutic modalities is likely to be partly responsible for the disappointing findings of recent AHF trials.

Clinical trials with endothelin receptor antagonists: what went wrong and where can we improve?

In the early 1990s, within three years of cloning of endothelin receptors, orally active endothelin receptor antagonists (ERAs) were tested in humans and the first clinical trial of ERA therapy in humans was published in 1995. ERAs were subsequently tested in clinical trials involving heart failure, pulmonary arterial hypertension, resistant arterial hypertension, stroke/subarachnoid hemorrhage and various forms of cancer. The results of most of these trials - except those for pulmonary arterial hypertension and scleroderma-related digital ulcers - were either negative or neutral. Problems with study design, patient selection, drug toxicity, and drug dosing have been used to explain or excuse failures. Currently, a number of pharmaceutical companies who had developed ERAs as drug candidates have discontinued clinical trials or further drug development. Given the problems with using ERAs in clinical medicine, at the Twelfth International Conference on Endothelin in Cambridge, UK, a panel discussion was held by clinicians actively involved in clinical development of ERA therapy in renal disease, systemic and pulmonary arterial hypertension, heart failure, and cancer. This article provides summaries from the panel discussion as well as personal perspectives of the panelists on how to proceed with further clinical testing of ERAs and guidance for researchers and decision makers in clinical drug development on where future research efforts might best be focused.

Emerging therapies for heart failure: renal mechanisms and effects

Improved understanding of the pathophysiology of salt and water homeostasis has provided a foundation for explaining the renal mechanisms of emerging therapies for heart failure, as well as why renal function might potentially be improved or harmed. These aspects are reviewed in this article for a number of newer therapies including adenosine, endothelin, and vasopressin receptor antagonists, as well as extracorporeal ultrafiltration. An appreciation of the complexity and sometimes opposing pathways of these approaches may explain their limited efficacy in early trials, in which there has not been a substantial improvement in patient or renal outcomes. In that there is often a balance between beneficial and maladaptive receptor actions and neurohumoral responses, this physiologic approach also provides insight into the rationale for combining therapies. Multi-agent strategies may thus maximize their effectiveness while minimizing adverse effects and tolerance. In this paper, the theoretical impact of the emerging agents based on their mechanism of action and pathophysiology of the disease is initially addressed. Then, the available clinical evidence for each class of drugs is reviewed with special emphasis on their effect on kidney-related parameters. Finally, a general overview of the complexity of the interpretation of trials is offered along with a number of potential explanations for the observed results.

Clinical development of pharmacologic agents for acute heart failure syndromes: a proposal for a mechanistic translational phase

Hospitalization for acute heart failure syndromes (AHFS) predicts a poor prognosis, with postdischarge mortality and rehospitalization rates reaching 45% within 60 to 90 days. Despite the use of evidence-based therapies and adherence to national process measures, these event rates have largely remained the same over the past decade. Given the current and growing burden of AHFS, there exists a substantial unmet need for novel therapies that improve outcomes. However, attempts to improve symptoms and/or reduce postdischarge events have failed to produce positive results, either because of safety and/or efficacy. These negative results may be related to the drug itself, the protocol in terms of patient selection and/or end points, and/or the trial execution. Although experts may not agree on the exact reasons to explain the lack of success to date of phase III trials in AHFS, there is agreement that clinical benefits observed in phase II trials were not reproduced in phase III trials. A different approach may be needed. In November of 2009, a meeting was held at the Food and Drug Administration with the primary purpose of identifying the reasons why benefits observed during phase II did not translate into benefits in phase III to improve future trial design. Although multiple domains of trial design were discussed, the participants identified a lack of in-depth understanding of novel molecules before pivotal trials in AHFS as a possible contributor to the disappointing results of recent large trials. In this brief report, we outline the T1 or translational phase of research for AHFS clinical development as an important first step toward greater success in AHFS clinical trials.

Haemodynamic effects of rolofylline in the treatment of patients with heart failure and impaired renal function

AIMS

The direct effects of adenosine A1 receptor antagonists on haemodynamic parameters in patients with acute heart failure (HF) remain largely unknown.

METHODS AND RESULTS

We evaluated the haemodynamic effects of the AA(1)RA rolofylline in 59 HF patients with concomitant renal impairment (estimated creatinine clearance 20-80 mL/min). Placebo or rolofylline 30 mg was administered as a 4 h infusion followed by intravenous (i.v.) loop diuretic administration. Haemodynamic measurements were carried out hourly up to 8 h post-dosing by pulmonary artery catheterization. Urine output, fractional excretion of sodium, potassium, urea, and uric acid, and blood urea nitrogen (BUN) and creatinine levels were also measured. In both groups, the changes from baseline in all haemodynamic indices except mean pulmonary artery pressure (PAP) were not clinically significant. Mean [95% confidence interval (CI)] PAP showed a placebo-adjusted decrease with rolofylline of -1.5 (-4.1, 1.1)mmHg at Hour 4 and -3.5 mmHg (95% CI: -6.2, -0.2) at Hour 8. There was a significant increase with rolofylline in diuresis [placebo-corrected mean (95% CI) change of 68 (20, 116)mL/h at Hour 2-4 and 103 (21, 185)mL/h at Hour 4-8] and in fractional excretion of sodium, potassium, and uric acid. Placebo-corrected changes in plasma levels of creatinine and BUN with rolofylline were non-significant.

CONCLUSION

Single administration of rolofylline in patients with HF and impaired renal function produced a slight decrease in mean PAP and consistently increased diuresis and natriuresis without compromising renal function, both before and after administration of i.v. loop diuretics.

The right heart and pulmonary circulation (III). The pulmonary circulation in heart failure

Pulmonary hypertension due to left heart disease is a pathophysiological and hemodynamic state which is present in a wide range of clinical conditions that affect left heart structures. Although the pulmonary circulation has traditionally received little attention, it is reasonable to say that today it is a fundamental part of cardiological evaluation. In patients with heart failure, the most important clinical factors are the presence of pulmonary hypertension and right ventricular function. These factors are also essential for determining prognosis and must be taken into account when making some of the most important therapeutic decisions. The pathophysiological process starts passively but later transforms into a reactive process. This latter process, in turn, has one component that can be reversed with vasodilators and another component that is fixed, in which the underlying mechanism is congestive vasculopathy (i.e. essentially medial hypertrophy and pulmonary arterial intimal fibrosis). Currently no specific therapy is available for this type of pulmonary hypertension and treatment is the same as for heart failure itself. The drugs that have been shown to be effective in pulmonary arterial hypertension have generally had a neutral effect in clinical trials. Nevertheless, we are involved in the clinical development of a number of groups of pharmacological compounds that will enable us to make progress in the near future.

Influence of liver cirrhosis on the pharmacokinetics, pharmacodynamics, and safety of tezosentan

This study investigates the pharmacokinetics, pharmacodynamics, and safety of the parenteral endothelin receptor antagonist tezosentan in patients with Child-Pugh classification B/C liver impairment. Cohorts I and II consist of 5 and 11 patients, respectively, with low serum bilirubin (<or=3.0 mg/dL) who receive intravenous tezosentan at 0.2 mg/h for 24 hours followed by 1.0 mg/h for 24 hours (cohort I) or 1.0 mg/h for 24 hours followed by 5.0 mg/h for 24 hours (cohort II). Cohort III (5 patients) receives the same treatment as cohort II but patients have high serum bilirubin (3.5-12 mg/dL). Each cohort includes 1 or 2 placebo patients (in total 4 patients). Compared with a historical control group of healthy subjects, the exposure to tezosentan is 3.1- and 8.5-fold greater in cohorts II and III, respectively. Patients are more sensitive than healthy subjects to the pharmacodynamic effects of tezosentan, as reflected in increases in endothelin-1 concentrations. Tezosentan is well tolerated. Decreases in blood pressure are similar in patients treated with tezosentan or placebo. Moderate/severe liver impairment is associated with increased exposure to tezosentan, which is more pronounced in patients with elevated bilirubin levels, necessitating dose reduction.

Relaxin for the treatment of patients with acute heart failure (Pre-RELAX-AHF): a multicentre, randomised, placebo-controlled, parallel-group, dose-finding phase IIb study

BACKGROUND

Most patients admitted for acute heart failure have normal or increase blood pressure. Relaxin is a natural human peptide that affects multiple vascular control pathways, suggesting potential mechanisms of benefit for such patients. We assessed the dose response of relaxin's effect on symptom relief, other clinical outcomes, and safety.

METHODS

In a placebo-controlled, parallel-group, dose-ranging study, 234 patients with acute heart failure, dyspnoea, congestion on chest radiograph, and increased brain natriuretic peptide (BNP) or N-terminal prohormone of BNP, mild-to-moderate renal insufficiency, and systolic blood pressure greater than 125 mm Hg were recruited from 54 sites in eight countries and enrolled within 16 h of presentation. Patients were randomly assigned, in a double-blind manner via a telephone-based interactive voice response system, to standard care plus 48-h intravenous infusion of placebo (n=62) or relaxin 10 microg/kg (n=40), 30 microg/kg (n=43), 100 microg/kg (n=39), or 250 microg/kg (n=50) per day. Several clinical endpoints were explored to assess whether intravenous relaxin should be pursued in larger studies of acute heart failure, to identify an optimum dose, and to help to assess endpoint selection and power calculations. Analysis was by modified intention to treat. This study is registered with ClinicalTrials.gov, number NCT00520806.

FINDINGS

In the modified intention-to-treat population, 61 patients were assessed in the placebo group, 40 in the relaxin 10 microg/kg per day group, 42 in the relaxin 30 microg/kg per day group, 37 in the relaxin 100 microg/kg per day group, and 49 in the relaxin 250 microg/kg per day group. Dyspnoea improved with relaxin 30 microg/kg compared with placebo, as assessed by Likert scale (17 of 42 patients [40%] moderately or markedly improved at 6 h, 12 h, and 24 h vs 14 of 61 [23%]; p=0.044) and visual analogue scale through day 14 (8214 mm x h [SD 8712] vs 4622 mm x h [9003]; p=0.053). Length of stay was 10.2 days (SD 6.1) for relaxin-treated patients versus 12.0 days (7.3) for those given placebo, and days alive out of hospital were 47.9 (10.1) versus 44.2 (14.2). Cardiovascular death or readmission due to heart or renal failure at day 60 was reduced with relaxin (2.6% [95% CI 0.4-16.8] vs 17.2% [9.6-29.6]; p=0.053). The number of serious adverse events was similar between groups.

INTERPRETATION

When given to patients with acute heart failure and normal-to-increased blood pressure, relaxin was associated with favourable relief of dyspnoea and other clinical outcomes, with acceptable safety.

Clazosentan to overcome neurological ischemia and infarction occurring after subarachnoid hemorrhage (CONSCIOUS-1): randomized, double-blind, placebo-controlled phase 2 dose-finding trial

BACKGROUND AND PURPOSE

This randomized, double-blind, placebo-controlled, dose-finding study assessed efficacy and safety of 1, 5, and 15 mg/h intravenous clazosentan, an endothelin receptor antagonist, in preventing vasospasm after aneurysmal subarachnoid hemorrhage.

METHODS

Patients (n=413) were randomized to placebo or clazosentan beginning within 56 hours and continued up to 14 days after initiation of treatment. The primary end point was moderate or severe angiographic vasospasm based on centrally read, blinded evaluation of digital subtraction angiography at baseline and 7 to 11 days postsubarachnoid hemorrhage. A morbidity/mortality end point, including all-cause mortality, new cerebral infarct from any cause, delayed ischemic neurological deficit due to vasospasm, or use of rescue therapy, was evaluated by local assessment. Clinical outcome was assessed by the extended Glasgow Outcome Scale at 12 weeks.

RESULTS

Moderate or severe vasospasm was reduced in a dose-dependent fashion from 66% in the placebo group to 23% in the 15 mg/h clazosentan group (risk reduction, 65%; 95% CI, 47% to 78%; P<0.0001). No significant effects were seen on secondary end points. Post hoc analysis using a centrally assessed morbidity/mortality end point that included death and rescue therapy but only cerebral infarcts and delayed ischemic neurological deficit due to vasospasm on central review showed a trend toward improvement with clazosentan (37%, 28%, and 29% in the 1, 5, and 15 mg/h groups versus 39% in the placebo group, nonsignificant). Clazosentan was associated with increased rates of pulmonary complications, hypotension, and anemia.

CONCLUSIONS

Clazosentan significantly decreased moderate and severe vasospasm in a dose-dependent manner and showed a trend for reduction in vasospasm-related morbidity/mortality in patients with aneurysmal subarachnoid hemorrhage when centrally assessed. Overall, the adverse effects were manageable and not considered serious.

Lack of renal improvement with nonselective endothelin antagonism with tezosentan in type 2 hepatorenal syndrome

Renal vasoconstriction is a key factor in the development of hepatorenal syndrome (HRS) and may be secondary to increased activities of endothelin-1, a potent renal vasoconstrictor. To assess the effects of tezosentan, a nonselective endothelin receptor antagonist, on renal function in patients with type 2 HRS, six male patients, 56.3 +/- 2.5 years old, with cirrhosis and type 2 HRS were treated with tezosentan; ascending doses of 0.3, 1.0, and 3.0 mg/hour, each for 24 hours, were used for the initial 2 patients, but a constant dose of 0.3 mg/hour for up to 7 days was used for the remaining 4 patients. The glomerular filtration rate, renal plasma flow, 24-hour urinary volume, mean arterial pressure (MAP), heart rate, tezosentan levels, and vasoactive hormones were measured daily. Albumin was given as required. The study was stopped early because of concerns about the safety of tezosentan in type 2 HRS. Five patients discontinued the study early; one stopped within 4 hours because of systemic hypotension (MAP < 70 mm Hg), and 4 patients stopped at approximately 4 days because of concerns about worsening renal function (serum creatinine increased from 180 +/- 21 to 222 +/- 58 micromol/L, P > 0.05) and decreasing urine volume (P = 0.03) but without a significant change in MAP. The plasma tezosentan concentrations were 79 +/- 34 ng/mL at a steady state during infusion at 0.3 mg/hour. The plasma endothelin-1 concentrations increased from 2.7 +/- 0.3 pg/mL at the baseline to 19.1 +/- 7.3 pg/mL (P < 0.05).

CONCLUSION

An endothelin receptor blockade potentially can cause a deterioration in renal function in patients with cirrhosis and type 2 HRS. Caution should be taken in future studies using endothelin receptor antagonists in these patients.

The endothelin system as a therapeutic target in cardiovascular disease: great expectations or bleak house?

There is considerable evidence that the potent vasoconstrictor endothelin-1 (ET-1) contributes to the pathogenesis of a variety of cardiovascular diseases. As such, pharmacological manipulation of the ET system might represent a promising therapeutic goal. Many clinical trials have assessed the potential of ET receptor antagonists in cardiovascular disease, the most positive of which have resulted in the licensing of the mixed ET receptor antagonist bosentan, and the selective ET(A) receptor antagonists, sitaxsentan and ambrisentan, for the treatment of pulmonary arterial hypertension (PAH). In contrast, despite encouraging data from in vitro and animal studies, outcomes in human heart failure have been disappointing, perhaps illustrating the risk of extrapolating preclinical work to man. Many further potential applications of these compounds, including resistant hypertension, chronic kidney disease, connective tissue disease and sub-arachnoid haemorrhage are currently being investigated in the clinic. Furthermore, experience from previous studies should enable improved trial design and scope remains for development of improved compounds and alternative therapeutic strategies. Although ET-converting enzyme inhibitors may represent one such alternative, there have been relatively few suitable compounds developed, and consequently, clinical experience with these agents remains extremely limited. Recent advances, together with an increased understanding of the biology of the ET system provided by improved experimental tools (including cell-specific transgenic deletion of ET receptors), should allow further targeting of clinical trials to diseases in which ET is involved and allow the therapeutic potential for targeting the ET system in cardiovascular disease to be fully realized.

Management of acute decompensated heart failure

Acute decompensated heart failure is the most common cause for hospitalization among patients over 65 years of age. It may result from new onset of ventricular dysfunction or, more typically, exacerbation of chronic heart failure symptoms. In-hospital mortality remains high for both systolic and diastolic forms of the disease. Therapy is largely empirical as few randomized, controlled trials have focused on this population and consensus practice guidelines are just beginning to be formulated. Treatment should be focused upon correction of volume overload, identifying potential precipitating causes, and optimizing vasodilator and beta-adrenergic blocker therapy. The majority of patients (>90%) will improve without the use of positive inotropic agents, which should be reserved for patients with refractory hypotension, cardiogenic shock, end-organ dysfunction, or failure to respond to conventional oral and/or intravenous diuretics and vasodilators. The role of aldosterone antagonists, biventricular pacing, and novel pharmacological agents including vasopressin antagonists, endothelin blockers, and calcium-sensitizing agents is also reviewed.

Clinical and Hemodynamic Effects of Bosentan Dose Optimization in Symptomatic Heart Failure Patients with Severe Systolic Dysfunction, Associated with Secondary Pulmonary Hypertension – A Multi-Center Randomized Study

OBJECTIVE

To evaluate the effects of bosentan on echo-derived hemodynamic measurements, and clinical variables in symptomatic heart failure (HF) patients.

METHOD

Multi- center, double-blind, randomized (2:1), placebo-controlled study comparing bosentan (8-125 mg b.i.d.) to placebo in patients with New York Heart Association class IIIb-IV HF, left ventricular ejection fraction <35% and systolic pulmonary artery pressure (SPAP) >40 mm Hg. Primary and secondary endpoints were change from baseline to 20 weeks in SPAP and cardiac index, respectively. Safety endpoints were treatment emergent adverse events (AEs), change in body weight, hemoglobin, hematocrit, systolic blood pressure and diuretic use.

RESULTS

Ninety-four patients enrolled: 60 to bosentan, 34 to placebo. There was no significant difference between the 2 arms in SPAP change (0.1 +/- 11.5 mm Hg , 95% confidence limit (CL) -5.4 to 5.2, p = 0.97), cardiac index shift (0.12 +/- 0.45, 95% CL -0.09 to 0.33 , p = 0.24 ) or any of the other 22 echocardiographic measurements obtained. Therapy-duration was longer in the placebo arm, while more patients in the bosentan arm experienced adverse and serious AEs.

CONCLUSION

In HF patients with left ventricular dysfunction and secondary pulmonary hypertension, bosentan did not provide any measurable hemodynamic benefit, and was associated with more frequent AEs, requiring drug discontinuation.

Right ventricular failure complicating heart failure: pathophysiology, significance, and management strategies

Right heart failure most commonly results from the complication of left heart failure (systolic or nonsystolic dysfunction) or pulmonary hypertension. Over the past decade, greater attention has been paid to the role of right ventricular failure in the morbidity and mortality associated with cardiomyopathy and pulmonary hypertension. The right ventricle is distinct from the left ventricle not only in its spatial localization, but also in its response to increased afterload and signaling mechanisms. This article discusses the role of right ventricular failure in the setting of heart failure as well as the clinical diagnosis and management of right ventricular failure.

Selective Endothelin-A Receptor Inhibition After Cardiac Surgery: A Safety and Feasibility Study

BACKGROUND

Increased synthesis and release of the bioactive peptide endothelin has been shown to change hemodynamics and postoperative recovery after cardiac surgery. However, the clinical effects of selective interruption of endothelin signaling have not been studied. Because the endothelin-A (ET-A) receptor subtype is the primary cardiovascular effector for endothelin, this study used the ET-A receptor antagonist sitaxsentan sodium (TBC11251Na) to evaluate: (1) dose-dependent changes in pulmonary artery pressure (PAP) and pulmonary (PVRI) and systemic (SVRI) vascular resistance index in patients undergoing on-pump coronary revascularization; and (2) whether ET-RA administration was associated with increased adverse events.

METHODS

Patients (n = 44, age, 62 +/- 1 years) were randomized to receive vehicle (n = 9) or different bolus infusions of ET-A receptor antagonist: 0.1 (n = 9), 0.5 (n = 9) 1.0 (n = 9), and 2.0 mg/kg (n = 8) at separation from cardiopulmonary bypass (CPB). Adverse events were tabulated until hospital discharge. Results were expressed as changes from a composite baseline value, or from time 0 due to a high degree of intrapatient measurement variability in the postoperative period.

RESULTS

PAP increased by 27% +/- 13% from baseline (19 +/- 1 mm Hg) in the vehicle group at 6 hours post-CPB (p < 0.05). PAP fell from this post-CPB vehicle value in a dose-dependent manner with the ET-A receptor antagonist; with a significant reduction observed at 2 mg/kg (7% +/- 8% increase from baseline, p < 0.05). PVRI was reduced by 28.6% +/- 16% from baseline (249 +/- 22 dyn x s x cm(-5) x m(-2)) in the 2 mg/kg ET-A receptor antagonist group at 30 minutes post-CPB and remained reduced up to 6 hours post-CPB (p < 0.05). SVRI was reduced from baseline (2770 +/- 106 dyn x s x cm(-5) x m(-2)) by 51% +/- 6% in the 2.0 mg/kg ET-A receptor antagonist group at 30 minutes post-CPB (p < 0.05) and remained reduced up to 6 hours post-CPB. A total of 203 adverse events were tabulated in the postoperative period and were equally distributed across the five treatment groups, with no direct attributions to ET-A receptor antagonist treatment.

CONCLUSIONS

This unique study demonstrates that heightened endothelin-A receptor activation contributes to hemodynamic changes in patients after CPB. Selective inhibition of the endothelin receptor system can be successfully and safely performed in patients undergoing cardiac surgery and thereby reveals a potential, and clinically relevant therapeutic target.

Up-regulated inflammatory factors endothelin, NFκB, TNFα and iNOS involved in exaggerated cardiac arrhythmias in l-thyroxine-induced cardiomyopathy are suppressed by darusentan in rats

The exaggerated cardiac arrhythmias in cardiomyopathy induced by L-thyroxine treatment are related to ion channelopathies and to an abnormal endothelin (ET) pathway. It was hypothesized that an increased incidence of ventricular fibrillation (VF) could be mediated by inflammatory factors including the ET pathway, nuclear factor kappa B (NFkappaB), tumor necrosis factor-alpha (TNFalpha) and inducible nitric oxide synthase (iNOS). Abnormal expression of NFkappaB, TNFalpha, iNOS and enhanced VF are linked with the activated ET pathway and a significant reversion could be achieved by the selective endothelin A receptor antagonist darusentan. Cardiomyopathy in rats was produced by L-thyroxine treatment (0.3 mg kg(-1) d(-1), sc) for 10 days. The mRNA expression of the ET pathway, NFkappaB, TNFalpha, iNOS and the activity of the redox system were assayed in association with the incidence of VF produced by coronary ligation/reperfusion. Darusentan was administered on days 6-10 of L-thyroxine treatment. The VF incidence, which was higher in the l-thyroxine cardiomyopathy group, was suppressed by darusentan. The mRNA levels of preproET-1, endothelin converting enzyme, endothelin receptor A (ET(A)R), endothelin receptor B (ET(B)R), NFkappaB, TNFalpha and iNOS in left ventricle were up-regulated in the cardiomyopathic heart. There was significant oxidative stress in this cardiomyopathy model. Darusentan suppressed the up-regulated mRNA levels of ET(A)R, ET(B)R, NFkappaB, TNFalpha, and iNOS. These results indicate that the high incidence of VF which is related to up-regulation of inflammatory factors in the cardiomyopathic myocardium is significantly suppressed by selective ET(A)R blockade.

Comparison of the pharmacokinetics, pharmacodynamics and tolerability of tezosentan between caucasian and Japanese subjects

AIM

To investigate the pharmacokinetics, pharmacodynamics and tolerability of the dual endothelin receptor antagonist tezosentan in caucasian and Japanese subjects.

METHODS

Twelve subjects of each ethnic origin were treated in a double-blind, randomized design with sequential 3-h infusions of 2.5, 5.0, 12.5 and 25 mg h(-1), or placebo. Vital signs, ECG and adverse events were recorded and blood samples collected for determination of plasma concentrations of tezosentan and endothelin-1 (ET-1).

RESULTS

Tezosentan was well tolerated in both ethnic groups with no clinically significant differences in laboratory measurements, ECG parameters and vital signs. The plasma concentration-time profiles of tezosentan were described by a three-compartment model with half-lives of approximately 5 min, 41 min and 3.6 h. Mean clearance and volume of distribution were approximately 35 l h(-1) and 20 l, respectively. Differences in the means (95% confidence intervals) between ethnic groups in these two parameters were 6.0 l h(-1) (-1.3, 13.3) and 4.3 l (-1.3, 9.9), respectively. Baseline ET-1 concentrations were similar but increases in response to tezosentan were greater in caucasian than in Japanese subjects. An indirect response model described the relationship between tezosentan and ET-1 plasma concentrations. The mean concentrations inhibiting 50% of ET-1 clearance (IC(50)) in caucasian and Japanese subjects were 243 and 227 ng ml(-1), respectively, with a difference in the means of 28.6 ng ml(-1) (-52.7, 110).

CONCLUSIONS

The data in healthy subjects suggest that caucasian and Japanese patients can be treated with a similar dosing regimen of tezosentan.

Future pharmacologic agents for treatment of heart failure in children

The addition of new agents to the armamentarium of treatment options for heart failure in pediatric patients is exciting and challenging. Administration of these therapies to pediatric patients will require careful scrutiny of the data and skilled application. Developmental changes in drug metabolism, excretion, and distribution are concerning in pediatric patients, and inappropriate evaluation of these parameters can have disastrous results. Manipulation of the neurohormonal pathways in heart failure has been the target of most recently developed pharmacologic agents. Angiotensin receptor blockers (ARBs), aldosterone antagonists, beta-blockers, and natriuretic peptides are seeing increased use in pediatrics. In particular, calcium sensitizing agents represent a new frontier in the treatment of acute decompensated heart failure and may replace traditional inotropic therapies. Endothelin receptor antagonists have shown benefit in the treatment of pulmonary hypertension, but their use in heart failure is still debatable. Vasopressin antagonists, tumor necrosis factor inhibitors, and neutral endopeptidase inhibitors are also targeting aspects of the neurohormonal cascade that are currently not completely understood. The future of pharmacologic therapies will include pharmacogenomic studies on new and preexisting therapies for pediatric heart failure. The education and skill of the practitioner when applying these agents in pediatric heart failure is of utmost importance.

Endothelin receptor antagonists

Endothelin receptor antagonists (ERAs) have been developed to block the effects of endothelin-1 (ET-1) in a variety of cardiovascular conditions. ET-1 is a powerful vasoconstrictor with mitogenic or co-mitogenic properties, which acts through the stimulation of 2 subtypes of receptors [endothelin receptor subtype A (ETA) and endothelin receptor subtype B (ETB) receptors]. Endogenous ET-1 is involved in a variety of conditions including systemic and pulmonary hypertension (PH), congestive heart failure (CHF), vascular remodeling (restenosis, atherosclerosis), renal failure, cancer, and cerebrovascular disease. The first dual ETA/ETB receptor blocker, bosentan, has already been approved by the Food and Drug Administration for the treatment of pulmonary arterial hypertension (PAH). Trials of endothelin receptor antagonists in heart failure have been completed with mixed results so far. Studies are ongoing on the effects of selective ETA antagonists or dual ETA/ETB antagonists in lung fibrosis, cancer, and subarachnoid hemorrhage. While non-peptidic ET-1 receptor antagonists suitable for oral intake with excellent bioavailability have become available, proven efficacy is limited to pulmonary hypertension, but it is possible that these agents might find a place in the treatment of several cardiovascular and non-cardiovascular diseases in the coming future.

Newer approaches to the pharmacological management of heart failure

PURPOSE OF REVIEW

The treatment of acute heart failure is gaining importance, specifically in the perioperative setting. Increasing evidence shows that established forms of therapy using beta-adrenergic inotropic drugs have no effect on long-term survival; thus, anesthetists and intensive care specialists are focusing on new strategies. This review examines, with respect to the literature of the past year, whether these strategies will gain significance in the perioperative setting.

RECENT FINDINGS

Owing to its unique efficacy profile, levosimendan, a calcium sensitizer, improves long-term survival in patients with acute heart failure and has been incorporated into the European Society of Cardiology guidelines. Improved heart function without increased oxygen consumption, anti-ischemic effects, no arrhythmogenic effect and positive effects on intestinal perfusion have been described. Despite the positive effects on hemodynamics and symptoms, tezosentan, an endothelin antagonist, did not improve outcome, perhaps due to too high dosages of the drug. Nesiritide, a recombinant brain natriuretic peptide, may represent an alternative to nitroglycerin and dobutamine and possibly have a benefit for survival. No final conclusions can yet be drawn, however. L-NAME, a nitric oxide synthase antagonist, represents a promising new approach for the treatment of cardiogenic shock. The results must be confirmed in large, randomized studies.

SUMMARY

For perioperative treatment of acute heart failure, levosimendan, nesiritide and L-NAME constitute promising alternatives to conventional inotropic and vasodilatory drugs. The strongest evidence for improving outcome is given for levosimendan. According to the present literature, tezosentan does not currently have any significance for treatment of perioperative heart failure.

Clinical trials update from the American College of Cardiology meeting: CARE-HF and the remission of heart failure, Women's Health Study, TNT, COMPASS-HF, VERITAS, CANPAP, PEECH and PREMIER

This article provides information and a commentary on landmark trials presented at the American College of Cardiology meeting held in March 2005, relevant to the pathophysiology, prevention and treatment of heart failure. All reports should be considered as preliminary data, as analyses may change in the final publication. CARE-HF showed that Cardiac Re-synchronisation Therapy, administered in addition to expert pharmacological management, reduced all cause mortality and CV hospitalisation in patients with moderate or severe heart failure and cardiac dyssynchrony. The Women's Health Study showed no benefit of vitamin E supplementation or aspirin in the primary prevention of CV disease. The TNT study showed that reducing LDL cholesterol to levels lower than currently recommended, produced a 22% reduction in the incidence of major cardiovascular events. In COMPASS, an implantable device that continuously monitors intra-cardiac pressures was shown to be safe and to improve care in patients with chronic heart failure. Tezosentan failed to show benefit in patients with acute heart failure in the VERITAS study. The CANPAP study failed to show a benefit of continuous positive airway pressure on mortality and heart transplantation in heart failure patients with central sleep apnoea. EECP therapy improved exercise capacity but had no effect on peak VO2 in heart failure patients in the PEECH study. In the PREMIER study the matrix metalloproteinase inhibitor PG-116800 failed to prevent LV remodelling following myocardial infarction.

Overview of randomized clinical trials in acute heart failure syndromes

Acute heart failure syndromes (AHFS) are among the most frequent causes of hospitalizations in the United States and Europe. Despite current therapies, patients with AHFS have high readmission and mortality rates. The randomized, controlled clinical trial is the standard by which contemporary therapies are evaluated, yet this tool of clinical science only recently has been rigorously applied to the development of novel therapies for patients with AHFS. This review briefly discusses some of the challenges presented in designing a clinical trial of therapies for AHFS and to describe some of the recent trials with respect to these issues in established drugs (such as milrinone, dobutamine, nitroglycerin, nitroprusside, and nesiritide) that have been approved by the US Food and Drug Administration (FDA). Recent trials of current investigational agents, such as levosimendan (the Randomized Multicenter Evaluation of Intravenous Levosimendan Efficacy Versus Placebo in the Short-Term Treatment of Decompensated Heart Failure [REVIVE], the Calcium Sensitizer or Inotrope or None in Low-Output Heart Failure [CASINO] study, and the Survival of Patients with Acute Heart Failure in Need of Intravenous Inotropic Support [SURVIVE] trial), tezosentan (the Randomized Intravenous Tezosentan [RITZ] study and the Value of Endothelin Receptor Inhibition with Tezosentan in Acute Heart Failure Studies [VERITAS]), and tolvaptan (the Acute and Chronic Therapeutic Impact of a Vasopressin Antagonist in Congestive Heart Failure [ACTIV-CHF] study), are also discussed.

Acutely decompensated congestive heart failure: new therapies for an old problem

Acutely decompensated heart failure is a common presentation to US emergency departments, and represents a major and increasing proportion of health burden. In contrast to chronic heart failure, where there have been numerous advances in care and corresponding decreases in morbidity and mortality, outcomes of patients with acutely decompensated heart failure have remained relatively unchanged with an approximate 10% 30-day mortality and almost 40% 1-year rehospitalization rate. This is reflected in the relative paucity of guidelines for this condition.

Tezosentan in patients with acute heart failure: design of the Value of Endothelin Receptor Inhibition with Tezosentan in Acute heart failure Study (VERITAS)

BACKGROUND

Endothelin 1 is a potent endogenous vasoconstrictor neurohormone, and endothelin 1 plasma concentrations predict adverse outcomes in patients with acute heart failure (AHF). Tezosentan, an intravenous endothelin receptor antagonist, improved hemodynamics in patients with AHF; however, its effects on morbidity and mortality have not been evaluated.

METHODS

The VERITAS program consists of 2 identical, double-blind, randomized, placebo-controlled, concurrently conducted trials (VERITAS-1 and VERITAS-2), performed in 150 centers in Europe, Israel, Australia, and North America. The program is designed to enroll at least 1760 patients hospitalized with dyspnea at rest because of AHF requiring intravenous therapy. In addition to conventional therapy, patients are randomized to receive tezosentan (5 mg/h for 30 minutes, then 1 mg/h for 24-72 hours) or matching placebo. The 2 prespecified primary end points are the incidence of death or worsening heart failure at 7 days in the combined studies and the change from baseline in dyspnea over the first 24 hours of treatment, measured using a visual analog scale in VERITAS-1 and VERITAS-2, individually.

RESULTS

Enrollment started in April 2003, and the program was discontinued in November 2005 because of the low probability of achieving a significant treatment effect.

CONCLUSIONS

No currently available agents have been shown in a prospective, randomized, clinical trial to improve outcomes in patients with AHF. Thus, the VERITAS program will provide valuable insights into the effect of tezosentan on clinical outcomes in patients with AHF, as well as hemodynamics and clinical symptoms.

Comparison of selective ETAand ETBreceptor antagonists in patients with chronic heart failure

BACKGROUND

The vasoconstrictor action of endothelin-1 (ET-1) is mediated through ET(A) and ET(B) receptor subtypes on vascular smooth muscle. ET(B) receptors are also present on the vascular endothelium where they mediate vasodilation. Animal studies suggest that the ET(B) receptor also acts as a clearance receptor for endothelin.

AIMS

To investigate the effects of a selective ET(A) and a selective ET(B) receptor antagonist alone and in combination on haemodynamics and circulating concentrations of ET-1 in patients with chronic heart failure.

RESULTS

Infusion of BQ-123 (n=10), a selective ET(A) receptor antagonist, led to systemic vasodilation and did not change plasma ET-1 concentrations (1.38+/-0.82 to 1.38+/-0.91 fmol/ml, ns). Infusion of BQ-788 (n=8) led to systemic vasoconstriction with a rise in plasma ET-1 (1.84+/-1.06 to 2.73+/-0.99 fmol/ml, p<0.01). The addition of BQ-123 to BQ-788 led to systemic and pulmonary vasodilation with no further increase in plasma ET-1 concentrations (2.80+/-1.14 to 2.90+/-1.20 fmol/ml, ns).

CONCLUSION

The rise in plasma ET-1 concentrations in response to selective blockade of ET(B) receptors and the associated adverse haemodynamic effects suggest that ET(B) receptors have a role in the clearance of ET-1 in man and that their blockade may not be advantageous for patients with heart failure.