Brain natriuretic peptide as bridge to therapy for heart failure

Role of Biomarkers for the Prevention, Assessment, and Management of Heart Failure: A Scientific Statement From the American Heart Association

BACKGROUND AND PURPOSE

Natriuretic peptides have led the way as a diagnostic and prognostic tool for the diagnosis and management of heart failure (HF). More recent evidence suggests that natriuretic peptides along with the next generation of biomarkers may provide added value to medical management, which could potentially lower risk of mortality and readmissions. The purpose of this scientific statement is to summarize the existing literature and to provide guidance for the utility of currently available biomarkers.

METHODS

The writing group used systematic literature reviews, published translational and clinical studies, clinical practice guidelines, and expert opinion/statements to summarize existing evidence and to identify areas of inadequacy requiring future research. The panel reviewed the most relevant adult medical literature excluding routine laboratory tests using MEDLINE, EMBASE, and Web of Science through December 2016. The document is organized and classified according to the American Heart Association to provide specific suggestions, considerations, or contemporary clinical practice recommendations.

RESULTS

A number of biomarkers associated with HF are well recognized, and measuring their concentrations in circulation can be a convenient and noninvasive approach to provide important information about disease severity and helps in the detection, diagnosis, prognosis, and management of HF. These include natriuretic peptides, soluble suppressor of tumorgenicity 2, highly sensitive troponin, galectin-3, midregional proadrenomedullin, cystatin-C, interleukin-6, procalcitonin, and others. There is a need to further evaluate existing and novel markers for guiding therapy and to summarize their data in a standardized format to improve communication among researchers and practitioners.

CONCLUSIONS

HF is a complex syndrome involving diverse pathways and pathological processes that can manifest in circulation as biomarkers. A number of such biomarkers are now clinically available, and monitoring their concentrations in blood not only can provide the clinician information about the diagnosis and severity of HF but also can improve prognostication and treatment strategies.

Amino-terminal pro-B-type natriuretic peptide as predictor of mortality in patients with symptomatic peripheral arterial disease: 5-year follow-up data from the Linz Peripheral Arterial Disease Study

BACKGROUND

Amino-terminal pro-B-type natriuretic peptide (NT-proBNP) has emerged as predictor of mortality endpoints in cardiac disease. In contrast, the prognostic value of NT-proBNP in patients with peripheral arterial disease (PAD) is unclear. Therefore, we aimed to evaluate the capability of NT-proBNP as a marker for long-term prognosis in atherosclerotic PAD.

METHODS

We obtained NT-proBNP serum concentrations in 487 consecutive patients with symptomatic PAD admitted to a tertiary-care hospital. The endpoint was defined as all-cause mortality, and the study participants were followed for 5 years.

RESULTS

Of the 487 patients enrolled, 114 died and 373 survived during follow-up. The median NT-proBNP concentration was higher among decedents than survivors (692 vs 143 ng/L; P < 0.001). Using the median NT-proBNP concentration of the entire cohort (213 ng/L) as threshold level, Kaplan-Meier curve analysis demonstrated that the survival probability was lower in patients with NT-proBNP above the median (log-rank test, P < 0.001). In the fully adjusted Cox proportional-hazards regression analysis, NT-proBNP >213 ng/L had a risk ratio of 2.27 (95% CI 1.27-4.03; P = 0.005) independent of age, sex, glomerular filtration rate, clinical stage of PAD, cardiovascular comorbidity, and other potential confounders. Further analyses showed that NT-proBNP added significantly to the value of established and emerging outcome predictors of PAD.

CONCLUSIONS

In this study, a NT-proBNP serum concentration >213 ng/L was a robust and independent predictor of 5-year all-cause mortality in patients with symptomatic PAD. Thus, NT-proBNP measurements can be considered a valuable tool for risk stratification in these patients.

Mineralocorticoid escape by the kidney but not the heart in experimental asymptomatic left ventricular dysfunction

Unlike healthy subjects, overt congestive heart failure cannot "escape" the sodium- and water-retaining actions of mineralocorticoid excess. It is undefined whether escape occurs in asymptomatic left ventricular dysfunction (ALVD), which is characterized by preserved sodium homeostasis, natriuretic peptide activation, and normal circulating aldosterone. We hypothesized that, in ALVD, mineralocorticoid excess with exogenous deoxycorticosterone acetate (DOCA) would overwhelm renal compensatory mechanisms, resulting in sodium and water retention, and promote renal and cardiac collagen deposition. ALVD was induced in 2 groups (N=5 each) of dogs by tachypacing at 180 bpm. Urine was collected daily and blood drawn at baseline and days 2, 5, 8, and 11. One group served as control (ALVD), and the other received DOCA (ALVD+DOCA) starting at day 2 of pacing. Urine flow and sodium excretion were unchanged in the ALVD group. In ALVD+DOCA, urine flow and sodium excretion decreased on the first 2 days DOCA was given but normalized starting day 4. Urine flow and urinary cGMP excretion increased in ALVD+DOCA after DOCA escape. Plasma atrial natriuretic peptide, B-type natriuretic peptide, and cGMP increased equally in both groups. There were no differences in cardiorenal and hemodynamic parameters in an acute study on day 11. Although renal collagen area fraction was similar, left ventricular collagen area fraction in ALVD+DOCA was significantly higher than in ALVD (3.3+/-0.4% versus 2.0+/-0.2%; P=0.012). We conclude that ALVD can escape the sodium- and water-retaining effects of mineralocorticoid excess. Despite renal escape, increased left ventricular collagen deposition suggests that the heart but not the kidney failed to escape the tissue effects of DOCA.

Daily dialyses decrease plasma levels of brain natriuretic peptide (BNP), a biomarker of left ventricular dysfunction

Brain natriuretic peptide or B-type natriuretic peptide (BNP) is a sensitive marker of heart disease. Plasma levels of BNP increase in left ventricular failure and determination of plasma BNP has become a useful tool in the diagnosis of heart failure. Hemodialysis (HD) patients may have elevated plasma levels of BNP, particularly predialysis, that correlate with echocardiographic signs of left ventricular dysfunction. High BNP levels are also a strong predictor of mortality in both nonrenal and HD patients. We studied plasma BNP levels in patients who changed from conventional thrice-weekly dialysis to daily dialysis 6 times a week while maintaining a total weekly time on dialysis of 12 hr. Twelve HD patients, mean age 55 years, had 4 hr of conventional thrice-weekly treatment for 4 weeks. Predialysis and postdialysis blood samples were obtained at the last dialysis. Patients were then dialyzed for 2 hr, 6 times weekly, for 4 weeks (daily dialysis). Again, predialysis and postdialysis blood samples were collected at the last HD. Brain natriuretic peptide plasma concentrations were determined by immunoradiometric assay. Predialysis BNP levels decreased from 194+/-51 ng/L (68+/-19 pmol/L; mean+SE) during thrice-weekly HD to 113+/-45 ng/L (41+/-18 pmol/L; p = 0.001) after 4 weeks on daily dialysis. With thrice-weekly HD, predialysis BNP levels were higher than postdialysis levels: 120+/-26 ng/L (39+/-8 pmol/L; p = 0.059). With daily dialysis, predialysis BNP levels did not differ significantly from postdialysis levels. Elevated predialysis plasma levels of BNP, considered sensitive and early markers of left ventricular dysfunction, decreased when patients were changed from conventional thrice-weekly HD to daily dialysis maintaining total hours of dialysis per week constant. Given the accumulated evidence that BNP is a biomarker of left ventricular dysfunction and can be used for risk stratification and guidance in pharmacotherapy of heart failure, daily dialysis appears to lead to less cardiac distress.

Brain (B-type) Natriuretic Peptide

Heart failure is the leading cause for hospitalization in the United States, resulting in over $8 billion in costs annually. Over 4.8 million Americans are afflicted with the disease and the number is increasing as the baby boomer generation continues to age. It is imperative that new and innovative modalities of therapy and diagnosis evolve as we continue to redefine the nature of heart failure and discover more about this debilitating disease. This article addresses the implications for endogenous brain (B-type) natriuretic peptide (BNP) testing in patients diagnosed with heart failure as well as the implications for the first available form of exogenous BNP, nesiritide. In addition, the pathophysiology of heart failure and traditional treatment modalities are discussed.

Increased Plasma Concentration of Natriuretic Peptides by Selective β1-Blocker Bisoprolol

Beta-blocker therapy has been shown to be associated with an increase in the plasma concentration of A-type natriuretic peptide (ANP). Whether the plasma concentration of B-type natriuretic peptide (BNP), which is mainly derived from ventricular tissue, is also increased and whether this increase is caused by increased production or decreased metabolism by down-regulation of the natriuretic peptide-clearance receptor remains to be established. In a double-blind crossover study effects of 8 weeks' treatment of bisoprolol,10 mg once daily, and losartan, 50 mg once daily, on plasma concentrations of ANP, BNP, and N-terminal (Nt)-ANP and ambulatory blood pressure (ABP) were measured in 24 hypertensive patients. With bisoprolol plasma concentrations of ANP and BNP increased (P < 0.001) by 93 +/- 88% (mean +/- SD) and 148 +/- 117%, whereas these parameters did not change with losartan. Nt-ANP, which is not metabolized by the NP clearance receptor, increased by 83 +/- 45%, and increments in ANP and Nt-ANP were related (r =0.77, P < 0.001). The decrease in ABP was greater with bisoprolol than with losartan. Monotherapy with bisoprolol, but not with losartan, is associated with substantial increments in plasma concentrations of ANP, Nt-ANP, and BNP. As the magnitude of the increase in ANP and Nt-ANP was comparable, the beta-blocker-induced increase in NPs is not likely to be explained by a decrease in NP clearance receptor density.

Major increase in brain natriuretic peptide indicates right ventricular systolic dysfunction in patients with heart failure

This study sought to investigate whether the presence of right ventricular systolic dysfunction with pre-existing left ventricular systolic dysfunction is associated with higher plasma brain natriuretic peptide (BNP) levels, compared with patients with isolated left ventricular dysfunction. Eighty-five patients referred for evaluation of isotopic ventricular function were prospectively included in the study. Left (LVEF) and right (RVEF) ventricular ejection fractions were evaluated by gated blood pool scintigraphy and compared with plasma BNP levels. BNP correlated negatively with LVEF, except in patients with ischaemic heart disease (P=0.09) and in patients with LVEF<40% (P=0.11). In contrast, BNP levels correlated negatively with RVEF for all subgroups. Among patients with RVEF<40%, no significant BNP difference was found between patients with or without additional left ventricular systolic dysfunction (P=0.51). Among patients with LVEF<40%, plasma BNP levels were significantly higher in patients with RVEF<40% than in patients with RVEF>/=40% (P=0.004) whereas age, renal function, clinical findings, ventricular volumes, LVEF or medication were not significantly different. In conclusion, an important increase in BNP levels in patients with left ventricular systolic dysfunction should be considered by cardiologists as an indication of high risk of right ventricular dysfunction and should justify further investigation.

Role of nonglycosidic inotropic agents: indications, ethics, and limitations

Nonglycosidic inotropic agents have been used for the short-term management of low output states and hypotension complicating acute myocardial infarction for several years. Without adequate reperfusion of the ischemic myocardium, inotropic agents are seldom effective in producing sustained hemodynamic responses. Furthermore, the potential exists for enhancement of ischemia and extension of myocardial necrosis. Thus, inotropic and vasopressors therapy should be regarded as temporary supportive treatment in patients with acute coronary syndrome and should be discontinued as soon as feasible. Parenteral sympathomimetic agents, usually dobutamine, and phosphodiesterase inhibitors, usually milrinone, are used for the management of exacerbations of chronic systolic heart failure. Although hemodynamics, and occasionally clinical status, improve, such therapy is associated with increased mortality and can potentially hasten a patient's demise. Nonparenteral sympathomimetics, such as ibopamine, phosphodiesterase-III inhibitors, such as milrinone and enoximone, calcium-sensitizing agents, such as pimobendan, and other novel inotropic agents, such as vesnarinone, all increase mortality of patients with chronic heart failure. Furthermore, newer noninotropic agents, such as B-natriuretic peptide, have been introduced for treatment of decompensated heart failure. New nonpharmacologic devices, such as biventricular pacing, are available for the treatment of advanced heart failure. Thus, indications for the use of presently available nonglycosidic inotropic agents are limited and should be considered only for short-term therapy or when no other treatment is available.

Surrogate end points in heart failure

OBJECTIVE

To describe the potential utility of a true surrogate marker of heart failure outcomes, historically investigate the validity of surrogates most commonly evaluated in heart failure, and identify specific end points offering the most potential for future use.

DATA SOURCES

A MEDLINE search (1966-June 2001) was completed to identify relevant literature. Additional references were also retrieved from selected articles. Search terms included b-type natriuretic peptide, cardiac remodeling, end-diastolic volume, heart failure, and surrogate end points.

DATA SYNTHESIS

By definition, true surrogate end points must predict outcomes associated with disease progression and response to therapy. A validated surrogate measure of mortality would render significant utility in both heart failure drug development and clinical practice. Improvements in traditional functional markers of heart failure, including ejection fraction and exercise capacity, have produced inconsistent results in regard to mortality in a number of clinical trials. Numerous measures of cardiac remodeling and neurohormonal activation, however, have proven to be reliable predictors of disease progression and therapeutic response. These findings have contributed significantly to the current understanding of heart failure pathophysiology and approach to treatment. Specifically, measures such as left-ventricular end-diastolic volume (LVEDV) and, potentially, b-type natriuretic peptide (BNP) concentrations may correlate with disease progression and parallel the mortality reductions observed with angiotensin-converting enzyme inhibitor and beta-blocker therapy.

CONCLUSIONS

Currently, LVEDV and plasma BNP offer the greatest potential as surrogate end points in heart failure. Further investigation of these measures is required before routine implementation in drug development and clinical practice can be justified.

Natriuretic peptides in the pathogenesis of cardiac dysfunction in the recipient fetus of twin-twin transfusion syndrome

OBJECTIVE

Although serial amnioreduction has substantially improved the prognosis of twin-twin transfusion syndrome, the majority of recipient twins develop cardiac dysfunction in utero and some have structural abnormalities in the neonatal period. The mechanism of cardiac dysfunction is unclear. To test the hypothesis that this occurs as a result of preload or pressure overload, we determined atrial natriuretic peptide and brain natriuretic peptide levels and their association with endothelin-1 in monochorionic pregnancies with or without chronic twin-twin transfusion syndrome.

PATIENTS AND METHODS

Matched maternal and fetal blood samples were obtained in utero from monochorial twin pregnancies complicated with (n = 14) and without twin-twin transfusion syndrome (n = 6). Serial fetal echocardiography assessment included cardiac anatomy, chamber size, cardiothoracic ratio, ventricular thickness, and the presence and severity of atrioventricular valve regurgitation. Postnatal echocardiograms were obtained on the surviving twins. The plasma levels of atrial natriuretic peptide, brain natriuretic peptide, and endothelin-1 were measured by use of radio-immunoassay.

RESULTS

Levels of fetal atrial natriuretic peptide (P <.001), brain natriuretic peptide (P <.001), and endothelin-1 (P <.001) in the recipient fetuses were higher than in donor twins. Fetal concentrations of atrial natriuretic peptide, brain natriuretic peptide, and endothelin-1 in the donor twins were similar to those concentrations in twins that did not have twin-twin transfusion syndrome. Fetal brain natriuretic peptide (P <.01) and endothelin-1 (P <.01) levels were significantly higher in the recipient fetuses when compared to those without severe cardiac dysfunction. A significant positive correlation was present between levels of fetal brain natriuretic peptide and endothelin-1 (y = 230.9 LOG(x) - 264.1, r =.82; P <.01). In contrast, there was no association between levels of fetal atrial natriuretic peptide and the severity of cardiac dysfunction, or with levels of fetal brain natriuretic peptide and endothelin-1.

CONCLUSION

Fetal natriuretic peptide levels were higher in the recipient twins than the co-twins, and the severity of cardiac dysfunction was related to levels of brain natriuretic peptide. These data, thereby, suggest that brain natriuretic peptide is a sensitive surrogate biochemical marker of cardiac dysfunction in the recipient twin.

Pro-atrial natriuretic peptide hormone from right atria is correlated with cardiac depression in septic patients

N-terminal pro-atrial natriuretic peptide [proANP(1-98)] has been extensively investigated in patients with chronic heart failure and ishemic heart disease. It is found to be a better marker of cardiac dysfunction than atrial natriuretic peptide (ANP). The possible involvement of proANP(1-98) in cardiac depression caused by sepsis has not been studied yet. Therefore, we analyzed atrial plasma concentration of proANP(1-98) in 17 septic patients with hemodynamic variables measured or calculated using pulmonary artery catheter. The results of altogether 96 measurements show a significant negative correlation of proANP(1-98) and cardiac index (p<0.024), oxygen delivery (p<0.03) and oxygen consumption (p<0.03). There is also a positive correlation with pulmonary vascular resistance (p<0.03). ProANP(1-98) is significantly higher in patients who developed acute respiratory distress syndrome (ARDS) (p<0.001). This study implies that proANP(1-98) is a possible novel hormone marker of cardiac depression caused by sepsis that could be used for prediction of ARDS.

Overview: old and new controversies in the treatment of advanced congestive heart failure

In 2001, patients with decompensated congestive heart failure can be treated with various intravenous inotropic agents, vasodilator agents, invasive hemodynamic monitoring, ventricular assist devices, and cardiac transplantation. The use of many of these agents is limited by toxicities and potentially incremental costs associated with intensive care unit stays. As new pharmacologic therapies become available, such as beta-blockers and natriuretic peptides, the combinatorial use of agents for the treatment of patients with decompensated heart failure presents new opportunities with potentially reduced toxicities. Finally, given the natural history of patients with advanced heart failure, it behooves all caregivers to understand the wishes and preferences of the patients who face life-threatening decompensation. This is particularly true with long-term intravenous inotropic therapy. This review article addresses some of the issues that can affect the balance between efficacy, toxicity, and patient preferences for end-of-life care.