Baseline and Serial Neurohormones in Patients With Congestive Heart Failure Treated With and Without Bucindolol: Results of the Neurohumoral Substudy of the Beta-Blocker Evaluation of Survival Study (BEST)

NT-proBNP Qualifies as a Surrogate for Clinical End Points in Heart Failure

N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a well-established biomarker in heart failure (HF) but controversially discussed as a potential surrogate marker in HF trials. We analyzed the NT-proBNP/mortality relationship in real-world data (RWD) of 108,330 HF patients from the IBM Watson Health Explorys database and compared it with the NT-proBNP / clinical event end-point relationship in 20 clinical HF studies. With a hierarchical statistical model, we quantified the functional relationship and interstudy variability. To independently qualify the model, we predicted outcome hazard ratios in five phase III HF studies solely based on NT-proBNP measured early in the respective study. In RWD and clinical studies, the relationship between NT-proBNP and clinical outcome is well described by an Emax model. The NT-proBNP independent baseline risk (R0 , RWD/studies median (interstudy interquartile range): 5.5%/3.0% (1.7-4.9%)) is very low compared with the potential NT-proBNP-associated maximum risk (Rmax : 55.2%/79.4% (61.5-89.0%)). The NT-proBNP concentration associated with the half-maximal risk is comparable in RWD and across clinical studies (EC50 : 3,880/2,414 pg/mL (1,460-4,355 pg/mL)). Model-based predictions of phase III outcomes, relying on short-term NT-proBNP data only, match final trial results with comparable confidence intervals. Our analysis qualifies NT-proBNP as a surrogate for clinical outcome in HF trials. NT-proBNP levels after short treatment durations of less than 10 weeks quantitatively predict hazard ratios with confidence levels comparable to final trial readout. Early NT-proBNP measurement can therefore enable shorter and smaller but still reliable HF trials.

Pharmacological interventions for heart failure in people with chronic kidney disease

BACKGROUND

Approximately half of people with heart failure have chronic kidney disease (CKD). Pharmacological interventions for heart failure in people with CKD have the potential to reduce death (any cause) or hospitalisations for decompensated heart failure. However, these interventions are of uncertain benefit and may increase the risk of harm, such as hypotension and electrolyte abnormalities, in those with CKD.

OBJECTIVES

This review aims to look at the benefits and harms of pharmacological interventions for HF (i.e., antihypertensive agents, inotropes, and agents that may improve the heart performance indirectly) in people with HF and CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies through 12 September 2019 in consultation with an Information Specialist and using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials of any pharmacological intervention for acute or chronic heart failure, among people of any age with chronic kidney disease of at least three months duration.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the records to identify eligible studies and extracted data on the following dichotomous outcomes: death, hospitalisations, worsening heart failure, worsening kidney function, hyperkalaemia, and hypotension. We used random effects meta-analysis to estimate treatment effects, which we expressed as a risk ratio (RR) with 95% confidence intervals (CI). We assessed the risk of bias using the Cochrane tool. We applied the GRADE methodology to rate the certainty of evidence.

MAIN RESULTS

One hundred and twelve studies met our selection criteria: 15 were studies of adults with CKD; 16 studies were conducted in the general population but provided subgroup data for people with CKD; and 81 studies included individuals with CKD, however, data for this subgroup were not provided. The risk of bias in all 112 studies was frequently high or unclear. Of the 31 studies (23,762 participants) with data on CKD patients, follow-up ranged from three months to five years, and study size ranged from 16 to 2916 participants. In total, 26 studies (19,612 participants) reported disaggregated and extractable data on at least one outcome of interest for our review and were included in our meta-analyses. In acute heart failure, the effects of adenosine A1-receptor antagonists, dopamine, nesiritide, or serelaxin on death, hospitalisations, worsening heart failure or kidney function, hyperkalaemia, hypotension or quality of life were uncertain due to sparse data or were not reported. In chronic heart failure, the effects of angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) (4 studies, 5003 participants: RR 0.85, 95% CI 0.70 to 1.02; I² = 78%; low certainty evidence), aldosterone antagonists (2 studies, 34 participants: RR 0.61 95% CI 0.06 to 6.59; very low certainty evidence), and vasopressin receptor antagonists (RR 1.26, 95% CI 0.55 to 2.89; 2 studies, 1840 participants; low certainty evidence) on death (any cause) were uncertain. Treatment with beta-blockers may reduce the risk of death (any cause) (4 studies, 3136 participants: RR 0.69, 95% CI 0.60 to 0.79; I² = 0%; moderate certainty evidence). Treatment with ACEi or ARB (2 studies, 1368 participants: RR 0.90, 95% CI 0.43 to 1.90; I² = 97%; very low certainty evidence) had uncertain effects on hospitalisation for heart failure, as treatment estimates were consistent with either benefit or harm. Treatment with beta-blockers may decrease hospitalisation for heart failure (3 studies, 2287 participants: RR 0.67, 95% CI 0.43 to 1.05; I² = 87%; low certainty evidence). Aldosterone antagonists may increase the risk of hyperkalaemia compared to placebo or no treatment (3 studies, 826 participants: RR 2.91, 95% CI 2.03 to 4.17; I² = 0%; low certainty evidence). Renin inhibitors had uncertain risks of hyperkalaemia (2 studies, 142 participants: RR 0.86, 95% CI 0.49 to 1.49; I² = 0%; very low certainty). We were unable to estimate whether treatment with sinus node inhibitors affects the risk of hyperkalaemia, as there were few studies and meta-analysis was not possible. Hyperkalaemia was not reported for the CKD subgroup in studies investigating other therapies. The effects of ACEi or ARB, or aldosterone antagonists on worsening heart failure or kidney function, hypotension, or quality of life were uncertain due to sparse data or were not reported. Effects of anti-arrhythmic agents, digoxin, phosphodiesterase inhibitors, renin inhibitors, sinus node inhibitors, vasodilators, and vasopressin receptor antagonists were very uncertain due to the paucity of studies.

AUTHORS' CONCLUSIONS

The effects of pharmacological interventions for heart failure in people with CKD are uncertain and there is insufficient evidence to inform clinical practice. Study data for treatment outcomes in patients with heart failure and CKD are sparse despite the potential impact of kidney impairment on the benefits and harms of treatment. Future research aimed at analysing existing data in general population HF studies to explore the effect in subgroups of patients with CKD, considering stage of disease, may yield valuable insights for the management of people with HF and CKD.

Natriuretic Peptides as Biomarkers of Treatment Response in Clinical Trials of Heart Failure

OBJECTIVES

This study sought to determine whether treatment-related changes in natriuretic peptides (NPs) predict longer-term therapeutic effects in clinical trials of heart failure (HF).

BACKGROUND

The lack of reliable predictors of efficacy of drugs and devices in HF has presented a major hurdle to the development and evaluation of novel therapies.

METHODS

The study conducted a trial-level analysis of 16 phase III chronic HF trials completed between 1987 and 2013 studying 18 therapeutic comparisons in 48,844 patients. Weighted Pearson correlation coefficients were calculated between average control- or placebo-corrected changes in NPs and longer-term treatment effects on clinical endpoints (expressed as log-transformed hazard ratios).

RESULTS

Median follow-up for clinical endpoints was 28 (25th to 75th percentile range: 18 to 36) months. NPs were available in a median of 748 (25th to 75th percentile range: 270 to 1,868) patients and measured at a median of 4 (25th to 75th percentile range: 3 to 6) months after randomization. Treatment-related changes in NPs were not correlated with longer-term treatment effects on all-cause mortality (r = 0.12; p = 0.63), but were correlated with HF hospitalization (r = 0.63; p = 0.008). Correlation with HF hospitalization improved when analyses were restricted to trials completed in the last decade (>2010; r = 0.92; p = 0.0095), using N-terminal pro-B-type NP assays (r = 0.65; p = 0.06), and evaluating inhibitors of the renin-angiotensin-aldosterone system (r = 0.97; p = 0.0002).

CONCLUSIONS

When examining a broad range of interventions, therapy-related changes in NPs appeared modestly correlated with longer-term therapeutic effects on hospitalization for HF, but not with effects on all-cause mortality. These observations raise important caveats regarding the use of NPs in phase II trials for decision making regarding phase III trials.

Plasma endothelin-1-related peptides as the prognostic biomarkers for heart failure: A PRISMA-compliant meta-analysis

BACKGROUND

Most studies reported that high plasma endothelin-1 (ET-1), big ET-1, and C-terminal proET-1 (CT-proET-1) were correlated with poor prognosis of heart failure (HF). However, available evidence remains controversial. To help solve the debate, we collected all the available studies and performed a meta-analysis.

METHODS

We searched the databases covering Embase, PubMed, Ovid, and Web of Science on June 28, 2017. The hazard ratio (HR) or risk ratio (RR) and its 95% confidence intervals (CIs) were collected and calculated by use of a random-effect model. Heterogeneity was assessed by Cochran's Q test, and publication bias was assessed by funnel plots with Egger's and Begg's linear regression test.

RESULTS

Thirty-two studies with 18,497 patients were included in the analysis. Results showed that circulating ET-1, big ET-1, and CT-proET-1 were positively correlated with high risk of adverse outcomes, with pooled RRs (95% CIs) of 2.22 (1.82-2.71, P < .001), 2.47 (1.93-3.17, P < .001), and 2.27 (1.57-3.29, P < .001), respectively. In the subgroup of death as primary outcome, the pooled RRs (95% CIs) were 2.13 (1.68-2.70, P < .001), 2.55 (1.82-3.57, P < .001), and 2.02 (1.39-2.92, P < .001) for ET-1, big ET-1, and CT-proET-1, respectively. No significant publication bias was observed in this study.

CONCLUSION

Our meta-analysis provided evidence that increased plasma levels of ET-1, big ET-1, and CT-proET-1 were associated with poor prognosis or mortality for HF populations.

Changes in Left Ventricular Ejection Fraction Predict Survival and Hospitalization in Heart Failure With Reduced Ejection Fraction

BACKGROUND

Left ventricular remodeling, as commonly measured by left ventricular ejection fraction (LVEF), is associated with clinical outcomes. Although change in LVEF over time should reflect response to therapy and clinical course, serial measurement of LVEF is inconsistently performed in observational settings, and the incremental prognostic value of change in LVEF has not been well characterized.

METHODS AND RESULTS

The β-Blocker Evaluation of Survival Trial measured LVEF by radionuclide ventriculography at baseline and at 3 and 12 months after randomization. We built a series of multivariable models with 16 clinical parameters plus change in LVEF for predicting 4 major clinical end points, including the trial's primary end point of all-cause mortality. Among 2484 patients with at least 1 follow-up LVEF, change in LVEF was the second most significant predictor (behind baseline creatinine) of all-cause mortality (adjusted hazard ratio for improvement in LVEF by ≥5 U responder versus nonresponder [95% confidence intervals] for all-cause mortality=0.62 [0.52-0.73]). Other end points, including heart failure hospitalization or the composite of all-cause mortality and heart failure hospitalization, yielded similar results. LVEF change ≥5 U was associated with a modest increase in discrimination when added to traditional predictors and was predictive of outcomes in both the bucindolol and placebo treatment groups. LVEF change as a predictor of outcomes was affected by sex and race, with evidence that LVEF improvement is associated with less survival benefit in African Americans and women.

CONCLUSIONS

Serial evaluation for LVEF change predicts both survival and heart failure hospitalization and provides a dynamic/real-time measure of prognosis in heart failure with reduced LVEF.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00000560.

Changes in N-terminal pro-B-type natriuretic peptide levels and outcomes in heart failure with preserved ejection fraction: an analysis of the I-Preserve study

AIMS

In patients with heart failure (HF) and reduced ejection fraction, decreases or increases in NT-proBNP levels are associated with better and worse outcomes, respectively. The association in HF and preserved ejection fraction (HF-PEF) is unknown. We examined the association between change in level of NT-proBNP and prognosis in patients with HF-PEF.

METHODS AND RESULTS

We examined the association between change in NT-proBNP from baseline to 6 months and cardiovascular (CV) death or HF hospitalization in 2612 participants in the Irbesartan in Patients with Heart Failure and Preserved Systolic Function Study (I-Preserve). Change in NT-proBNP was modelled as a restricted cubic spline in a Cox model after adjusting for baseline NT-proBNP and known prognostic variables. Median change in NT-proBNP from baseline was -7 pg/mL (interquartile range -143 to +108). After adjustment, a 1000 pg/mL decrease in NT-proBNP from baseline was associated with a reduction in the risk of CV death or HF hospitalization [hazard ratio (HR) 0.73, 95% confidence interval (CI) 0.53-1.02]; a 1000 pg/mL increase was associated with an increase in risk (HR 2.01, 95% CI 1.50-2.69). Beyond a 1000 pg/mL rise or fall, there was little additional change in risk. Addition of change in NT-proBNP at 6 months to a model with only baseline NT-proBNP improved the C-statistic from 0.752 to 0.769 (P = 0.013).

CONCLUSION

In HF-PEF, a rise in NT-proBNP was associated with an increase in risk of CV death or HF hospitalization and a fall was associated with a trend towards a decrease in risk. NT-proBNP may be a useful marker to monitor prognosis in this condition.

Do optimal prognostic thresholds in continuous physiological variables really exist? Analysis of origin of apparent thresholds, with systematic review for peak oxygen consumption, ejection fraction and BNP

Background

Clinicians are sometimes advised to make decisions using thresholds in measured variables, derived from prognostic studies.

Objectives

We studied why there are conflicting apparently-optimal prognostic thresholds, for example in exercise peak oxygen uptake (pVO₂), ejection fraction (EF), and Brain Natriuretic Peptide (BNP) in heart failure (HF).

Data Sources and Eligibility Criteria

Studies testing pVO₂, EF or BNP prognostic thresholds in heart failure, published between 1990 and 2010, listed on Pubmed.

Methods

First, we examined studies testing pVO₂, EF or BNP prognostic thresholds. Second, we created repeated simulations of 1500 patients to identify whether an apparently-optimal prognostic threshold indicates step change in risk.

Results

33 studies (8946 patients) tested a pVO₂ threshold. 18 found it prognostically significant: the actual reported threshold ranged widely (10–18 ml/kg/min) but was overwhelmingly controlled by the individual study population's mean pVO₂ (r = 0.86, p<0.00001). In contrast, the 15 negative publications were testing thresholds 199% further from their means (p = 0.0001). Likewise, of 35 EF studies (10220 patients), the thresholds in the 22 positive reports were strongly determined by study means (r = 0.90, p<0.0001). Similarly, in the 19 positives of 20 BNP studies (9725 patients): r = 0.86 (p<0.0001).

Second, survival simulations always discovered a “most significant” threshold, even when there was definitely no step change in mortality. With linear increase in risk, the apparently-optimal threshold was always near the sample mean (r = 0.99, p<0.001).

Limitations

This study cannot report the best threshold for any of these variables; instead it explains how common clinical research procedures routinely produce false thresholds.

Key Findings

First, shifting (and/or disappearance) of an apparently-optimal prognostic threshold is strongly determined by studies' average pVO₂, EF or BNP. Second, apparently-optimal thresholds always appear, even with no step in prognosis.

Conclusions

Emphatic therapeutic guidance based on thresholds from observational studies may be ill-founded. We should not assume that optimal thresholds, or any thresholds, exist.

Biomarkers as surrogate end points in heart failure trials

Despite the continued growth of heart failure as a major public health problem, the development of new therapies for heart failure has slowed and recent studies have been neutral, suggesting the need for a reappraisal of the clinical research enterprise. Surrogate end points, defined as measurements that are used as substitutes for the more clinically meaningful end points, can play a valuable role in clinical trials by accelerating the timeline for determining appropriate dosages, efficacy, and safety. Biomarkers, such as the natriuretic peptides, have many of the characteristics of valid surrogates but have not been sufficiently validated for widespread use. Ongoing research into the role of biomarkers as surrogates may lead to better clinical trial design and more efficient development of new therapies for heart failure.

Bucindolol: a pharmacogenomic perspective on its use in chronic heart failure

Bucindolol is a non-selective β-adrenergic receptor blocker with α-1 blocker properties and mild intrinsic sympatholytic activity. The Beta-Blocker Evaluation of Survival Trial (BEST), which is the largest clinical trial of bucindolol in patients with heart failure, was terminated prematurely and failed to show an overall mortality benefit. However, benefits on cardiac mortality and re-hospitalization rates were observed in the BEST trial. Bucindolol has not shown benefits in African Americans, those with significantly low ejection fraction and those in NYHA class IV heart failure. These observations could be due to the exaggerated sympatholytic response to bucindolol in these sub-groups that may be mediated by genetic polymorphisms or changes in gene regulation due to advanced heart failure. This paper provides a timely clinical update on the use of bucindolol in chronic heart failure.