Transient reduction without normalization of brain natriuretic peptide early after heart transplantation

Brain natriuretic peptide and right heart dysfunction after heart transplantation

Heart transplantation (HT) should normalize cardiac endocrine function, but brain natriuretic peptide (BNP) levels remain elevated after HT, even in the absence of left ventricular hemodynamic disturbance or allograft rejection. Right ventricle (RV) abnormalities are common in HT recipients (HTx), as a result of engraftment process, tricuspid insufficiency, and/or repeated inflammation due to iterative endomyocardial biopsies. RV function follow-up is vital for patient management as RV dysfunction is a recognized cause of in-hospital death and is responsible for a worse prognosis. Interestingly, few and controversial data are available concerning the relationship between plasma BNP levels and RV functional impairment in HTx. This suggests that infra-clinical modifications, such as subtle immune system disorders or hypoxic conditions, might influence BNP expression. Nevertheless, due to other altered circulating molecular forms of BNP, a lack of specificity of BNP assays is described in heart failure patients. This phenomenon could exist in HT population and could explain elevated BNP plasmatic levels despite a normal RV function. In clinical practice, intra-individual change in BNP over time, rather than absolute BNP values, might be more helpful in detecting right cardiac dysfunction in HTx.

Brain natriuretic Peptide production and secretion in inflammation

Gene expression and secretion of the cardiac polypeptide hormones atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) are simultaneously upregulated in various cardiac disorders such as congestive heart failure, ischemic heart disease, and hypertensive heart disease, in which hemodynamic or neuroendocrine changes are key components in the progression of disease. However, during acute cardiac allograft rejection, plasma BNP levels are increased but not those of ANF. Successful treatment of the rejection episode decreases the elevated plasma BNP to prerejection values suggesting that substances related to inflammation may selectively influence BNP gene expression. Indeed, cytokines such as TNFα and IL-1β selectively stimulate cardiac BNP at the transcriptional and translational levels in cardiomyocyte cultures without affecting ANF. This selective BNP increase is seen in vivo, in addition to acute cardiac allograft rejection, in several circumstances where inflammation significantly contributes to the pathogenesis of disease such as in sepsis and in acute myocarditis.

Endocrine heart after lung transplantation: increased brain natriuretic peptide is related to right ventricular function

Brain natriuretic peptide (BNP) increases in proportion to the extent of right ventricular dysfunction in pulmonary hypertension and after heart transplantation. No data are available after lung transplantation. Clinical, biological, respiratory, echocardiographic characteristics and circulating BNP and its second messenger cyclic guanosine monophosphate (cGMP) were determined in thirty matched subjects (10 lung-, 10 heart-transplant recipients (Ltx, Htx) and 10 healthy controls). Eventual correlations between these parameters were investigated. Heart rate and pulmonary arterial blood pressure were slightly increased after transplantation. Creatinine clearance was decreased. Mean of forced expiratory volume in 1 s was 76.6 +/- 5.3% and vital capacity was 85.3 +/- 6.4% of the predicted values in Ltx. BNP was similarly increased in Ltx and Htx, as compared with control values (54.1 +/- 14.2 and 45.6 +/- 9.2 vs. 6.2 +/- 1.8 pg/ml, respectively). Significant relationships were observed between plasma BNP and cGMP values (r = 0.62; P < 0.05 and r = 0.75; P < 0.01, in Ltx and Htx) and between BNP and right ventricular fractional shortening and tricuspid E/Ea ratio in Ltx (r = -0.75 and r = 0.93; P < 0.01, respectively). BNP is increased after lung transplantation, like after heart transplantation. The relationships observed suggest that the cardiac hormone might counterbalance possible deleterious effects of lung-transplantation on right functioning of patient's heart.

Time-dependent changes in B-type natriuretic peptide after heart transplantation: correlation with allograft rejection and function

Endomyocardial biopsy is the gold standard to diagnose cardiac allograft rejection, although a noninvasive modality such as brain natriuretic peptide (BNP) is attractive. The authors examined the correlation of BNP levels with rejection patterns and allograft function in cardiac allograft recipients followed up to 8 years. One hundred forty-four consecutive patients underwent endomyocardial biopsy, right heart catheterization, and blood sampling. BNP levels decreased during the first 6 months after transplant but then reached a plateau. Time-dependent correlations were made between BNP levels and allograft rejection, left ventricular ejection fraction, pulmonary capillary wedge pressure, right atrial pressure, and serum creatinine. BNP levels were not different between patients with any rejection pattern and no rejection prior to or after 6 months following transplant. BNP levels did not correlate with ejection fraction, pulmonary capillary wedge pressure, right atrial pressure, or creatinine in the first 6 months after transplant. Statistically significant correlations existed between BNP and these parameters after 6 months following transplant. In cardiac transplant recipients, BNP levels decrease in the first 6 months following transplant and then reach a plateau regardless of the presence, type, or severity of allograft rejection. BNP levels do predict allograft rejection but correlate with allograft function after 6 months following transplant.

Prognostic relationship between two serial determinations of B-type natriuretic peptide and medium-long-term events in heart transplantation

BACKGROUND

Persistent elevation of B-type natriuretic peptide (BNP) levels in the first year after transplant appears to be associated with an adverse prognosis. However, there are no data on the prognostic value of two serial determinations of BNP at the end of the first year after transplant in clinically stable patients.

OBJECTIVES

The purpose of this study was to analyze the association between the increase in two serial determinations of BNP at the end of the first year and the subsequent development of events in medium-long-term follow-up.

METHODS

An observational study was conducted in a consecutive series of 71 patients transplanted between January 1999 and January 2001. Patients who were "unstable" or had other conditions that could elevate BNP levels (rejection, elevated pulmonary pressures, renal dysfunction, depressed ventricular function or severe graft vascular disease) were also excluded. The final number of patients included was 51. BNP determinations were performed at 9 and 12 months post-transplant at the same time as biopsies. Three groups were formed depending on the relationship between the two determinations: Group 1 (20 patients), decrease >20%; Group 2 (16 patients), change <20%; and Group 3 (15 patients), increase >20%. The following were considered events: death; late rejection; and ventricular dysfunction associated or not with graft vascular disease.

RESULTS

The baseline clinical profile was similar in the three groups. There was a significant difference in the rate of events (Group 1, 10%; Group 2, 32%; Group 3, 53%; p < 0.017). Event-free survival was statistically different between the groups (p = 0.017), mainly because of the large difference between Groups 1 and 3 (p = 0.003). Thus, cumulative event-free survival at 3,000 days was 89.4% for Group 1, 68.3% for Group 2 and 48.2% for Group 3.

CONCLUSIONS

The increase between two serial determinations of BNP levels at the end of the first year post-transplant could identify a subgroup of patients with poor outcome.

Does circulating BNP normalize after heart transplantation in patients with normal hemodynamic and right and left heart functions?

BACKGROUND

Increased brain natriuretic peptide (BNP) in cardiovascular disease is thought to be a compensatory protective mechanism allowing to delay the occurrence of terminal heart failure. Heart transplantation should normalize the neuroendocrine balance but BNP remains elevated in stable heart-transplant recipients (Htx). Such increase has been related to persistent endothelial and cardiac dysfunctions. The purpose of this study was to determine whether selected Htx, presenting with normal hemodynamic and cardiac systolic and diastolic functions on both side of the heart, show a normalization of their BNP plasma values.

METHODS

Of a cohort of well-being 26 Htx, we selected 12 patients with normal hemodynamics and left and right heart systolic and diastolic functions and compared their circulating BNP, cyclic guanosine monophosphate (cGMP) (the BNP second messenger) and endothelin-1 (ET) values with that of 12 age-, body mass index- and mean arterial pressure-matched controls. Cardiac function determination by echodoppler included cardiac filling pressures assessment using tissue Doppler imaging. Blood samples for biological and hormonal determinations were drawn at rest, within 15 min before echocardiography.

RESULTS

As selected, hemodynamic and left and right heart systolic and diastolic functions were located in the normal range in Htx. Plasma ET value was also similar in Htx and controls (20.7 +/- 0.9 vs. 19.6 +/- 0.9 fmol/mL). However, circulating BNP, like cGMP, was still significantly increased after heart transplantation, when compared with controls (33.8 +/- 8.5 vs. 4.0 +/- 0.9 pg/mL, p = 0.002 and 8.2 +/- 1.1 vs. 4.4 +/- 0.3 nmol/L, p = 0.003) for BNP and cGMP, respectively, in Htx and controls. Interestingly, the sole correlation observed was between BNP and cGMP (r = 0.85, p < 0.0001) after heart transplantation.

CONCLUSIONS

After heart transplantation, BNP remained increased despite the normalization of hemodynamic and cardiac systolic and diastolic functions. This suggests that such endocrine heart stimulation should not be viewed only as a hemodynamic marker in Htx. Further studies will be useful to investigate the role of pro-inflammatory cytokines and whether elevated BNP still possesses antifibrotic properties, further supporting the interest of enhancing its activity after heart transplantation.

Probrain Natriuretic Peptide and C-Reactive Protein as Markers of Acute Rejection, Allograft Vasculopathy, and Mortality in Heart Transplantation

BACKGROUND

N-terminal probrain natriuretic peptide (NT-proBNP) and C-reactive protein (CRP) are useful in risk stratification of patients with congestive heart failure. They could also be markers of distinctly altered hormonal and immunological milieus, but the combined prognostic value of these biomarkers in heart transplant (HTx) recipients has not been assessed previously.

METHODS

We sought to assess the individual and combined value of NT-proBNP and CRP as markers of acute rejection, cardiac allograft vasculopathy (CAV) and all-cause mortality in HTx recipients. We evaluated 101 patients for acute rejection and 210 patients for CAV and all-cause mortality. Patients evaluated for rejection had serial endomyocardial biopsies and plasma sampling performed during the first year postHTx. All other patients had plasma samples taken upon inclusion at an annual visit. Median follow-up for CAV and all-cause mortality was 2.2 years and 5.4 years, respectively.

RESULTS

Altogether, 1131 biopsy procedures were performed, and increased NT-proBNP and CRP levels were not useful markers of acute cellular rejection. In total, 78 (37%) patients developed CAV, and 39 (19%) patients died. Neither biomarker was a predictor of CAV, but both were independent predictors of mortality. When combining both biomarkers, elevated levels of both NT-proBNP and CRP identified patients at highest risk for CAV (HR 2.10, P=0.01) and all-cause mortality (HR 3.14, P=0.01).

CONCLUSIONS

In HTx recipients, NT-proBNP and CRP are not useful as markers of acute cellular rejection during the first year postHTx, but combined analysis adds significantly to their predictive value for development of CAV and all-cause mortality.

Brain natriuretic peptide predicts serious cardiac allograft rejection independent of hemodynamic measurements

BACKGROUND

Serum brain natriuretic peptide (BNP) has been reported to be elevated in heart transplant recipients with both cellular and vascular rejection. Whether BNP can be used to help predict the severity of rejection is not well established.

METHODS

We analyzed serial BNP measurements obtained during endomyocardial biopsy procedures in consecutive heart transplant patients occurring >45 days after transplantation. To eliminate potential confounding from prior rejection episodes, we included only observations in which the previous biopsy grade was 0 or 1A. Multivariable linear regression was performed examining the outcome of increasing seriousness of rejection, defined as grade 0 < 1A < 2 < 1B < 3A < vascular rejection. A univariable logistic regression model was performed using log-transformed BNP as a predictor of vascular rejection.

RESULTS

There were 77 patients, with 161 separate observations. Median time between transplantation and first assessment was 6.0 months (interquartile range, 2.1, 31.6). Using multivariable linear regression, 3 factors were significantly associated with biopsy score: pulmonary capillary wedge pressure (p < 0.0001), BNP (p = 0.003), and heart rate (p = 0.01). Even after other significant univariable predictors (including pulmonary capillary wedge pressure) were forced into the model, BNP remained a significant predictor of biopsy score (p = 0.02). Log BNP was a significant univariable predictor of vascular rejection, with an odds ratio of 12.55 (per 1 unit increase, 95% confidence interval 3.43-45.84; p = 0.0001) and a model c-statistic of 0.91.

CONCLUSIONS

BNP predicts new episodes of serious cardiac allograft rejection, particularly vascular rejection, independent of hemodynamic measurements, and may be a useful part of rejection surveillance.

Determinants of B-type natriuretic peptide plasma levels in the chronic phase after heart transplantation*

Determinants of B-type natriuretic peptide (BNP) plasma levels in the chronic phase after heart transplantation remain unclear. BNP was measured in 105 stable long-term heart transplant recipients with normal left ventricular function by echocardiography and correlated with clinical, demographic and hemodynamic parameters. Multivariate analysis revealed a significant correlation of BNP with female recipient gender (P = 0.006), time post-transplant (P =0.006), donor age (P = 0.007), angiographic signs of transplant vasculopathy (TVP) (P = 0.03), serum creatinine level (P = 0.04), and a strong trend for diastolic dysfunction (P = 0.09). Donor gender, recipient age, cyclosporin A blood levels, rejection history, and pulmonary artery pressure had no independent effect on BNP. BNP after heart transplantation appears to be influenced both by established general determinants (female gender, renal function) and transplant-specific determinants such as time post-transplant, donor age and potentially also TVP. In order to determine the value of BNP as a potential surrogate marker of TVP serial intraindividual measurements appear appropriate.

Usefulness of N-terminal-pro-brain natriuretic peptide levels in predicting survival in heart transplant recipients

We evaluated the prognostic value of plasma N-terminal-pro-brain natriuretic peptide (NT-pro-BNP) in 71 transplanted heart recipients during a 38 +/- 2 month follow-up. The negative predictive value of NT-pro-BNP levels </=800 pg/ml to predict death was 97% (95% confidence interval 92 to 100). Thus, NT-pro-BNP levels </=800 pg/ml predict a middle-term good survival in transplanted heart recipients.

BNP Consensus Panel 2004: A Clinical Approach for the Diagnostic, Prognostic, Screening, Treatment Monitoring, and Therapeutic Roles of Natriuretic Peptides in Cardiovascular Diseases

Among the most exciting developments in the field of heart failure in recent times has been the rediscovery of the natriuretic peptide system and its pleuripotent effects on cardiac structure and function. This is particularly true of its natriuretic and hemodynamic effects. There has been an explosion of the knowledge base seeking to understand the wide range of homeostatic, regulatory, and counter-regulatory functions in which the natriuretic peptide system participates. Additional interest has been stimulated by advances in technology such as point-of-care and core laboratory BNP assays and the use of the recombinant B-type natriuretic peptide nesiritide as a treatment option. Despite this recent interest, the available literature lacks a comprehensive expert review of the current science and roles of natriuretic peptides for diagnostic, prognostic, screening, treatment monitoring, and therapeutic purposes. More importantly, a summary updating and guiding the clinician on most of these advances was lacking. An expert Consensus Panel with basic, methodological, and clinical expertise was convened to summarize current knowledge in these areas and the findings and consensus statements are contained herein.

Usefulness of an elevated B-type natriuretic peptide to predict allograft failure, cardiac allograft vasculopathy, and survival after heart transplantation

B-type natriuretic peptide (BNP) has emerged as an important marker of ventricular wall stress and is predictive of hemodynamic abnormalities in heart transplantation despite "preserved" systolic function. We evaluated the capacity of BNP to predict deaths due to allograft failure in 62 patients long after heart transplantation (mean 5 +/- 2.5 years). Based on the median tendency of measurement of BNP in the absence of rejection during stable surveillance, 2 distinct patient groups were identified as having low BNP (n = 39, < 250 pg/ml; median BNP 70 pg/ml) and high BNP (n = 23, > or =250 pg/ml; median BNP 592 pg/ml). No differences between the 2 BNP groups were noted with regard to age, gender, race, time after transplantation, diabetes mellitus, hypertension, and hyperlipidemia with measurement of BNP. Multivariable analysis showed that decreased left ventricular ejection fraction, angiographic coronary artery disease, and increased serum creatinine were independent predictors of elevated BNP. Cardiac deaths were significantly greater in those with high BNP levels (35%) than in those with low BNP (2.5%, p = 0.01). Absence of significant angiographic coronary artery disease coupled with a BNP of < 250 pg/ml was associated with the lowest event rate (0%), whereas patients with coronary artery disease and BNP > or =250 pg/ml exhibited a 50% cardiac death rate (p <0.01 for trend). Cox's model confirmed that increased BNP and decreased left ventricular ejection fraction are independent predictors of poor survival. Survival analysis associated lower BNP levels with an excellent long-term survival rate (95%) and higher BNP levels with a markedly decreased survival rate (60%, p = 0.002). Higher BNP levels in patients long after heart transplantation are associated with allograft dysfunction and cardiac allograft vasculopathy and are strongly and independently predictive of cardiovascular death.

B-type natriuretic peptide in heart transplantation: an important marker of allograft performance

The successful management of a cardiac allograft recipient centers around detection of allograft dysfunction early and preferably in a noninvasive manner. Up to this point, echocardiography or right heart catherization with endomyocardial biopsy are the only definitive methods available to diagnose allograft dysfunction. However, these methods do not reflect early structural changes and neurohormonal aberrations involved in allograft dysfunction. B-type natriuretic peptide (BNP) reflects ventricular wall stress and pressure and early studies have intimated potential usefulness of this marker in heart transplantation. Recent studies utilizing point-of-care BNP assay in heart transplant recipients have demonstrated elevated BNP levels at baseline compared with controls. Furthermore, the two most significant correlates of BNP levels are central hemodynamic perturbations despite preserved systolic function and presence of right sided cardiac dysfunction. Initial investigations have demonstrated BNP levels to serve as prognostic marker for cardiac related events and to track responses to therapeutic interventions. Further studies are needed to further assess the utility of BNP as surrogate marker for cardiac function and adaptation.

Aminoterminal pro-brain natriuretic peptide and ventricular filling pressures in heart transplant recipients

We tested the hypothesis that, in heart transplant recipients, plasma aminoterminal pro-brain natriuretic peptide (NT-proBNP) dosage is useful for diagnosis of high ventricular loading pressures in the absence of systolic dysfunction. We studied 60 consecutive transplanted heart recipients without systolic dysfunction at 1 to 16 years after transplantation. We found that, in these patients with frequent high ventricular filling pressures, plasma NT-proBNP was highly correlated with creatininemia and not correlated with ventricular loading pressures. These results do not support the hypothesis that NT-proBNP is useful for diagnosis of isolated diastolic dysfunction in transplanted heart recipients.

Usefulness of B-type natriuretic peptide levels in predicting hemodynamic perturbations after heart transplantation despite preserved left ventricular systolic function

The aim of this prospective study was to evaluate the association of peripheral B-type natriuretic peptide (BNP) levels with clinical symptoms and central hemodynamic and echocardiographic measures in cardiac transplantation. BNP reflects ventricular wall stress and correlates with severity of heart failure. No previous investigation has comprehensively assessed the rapid bedside BNP assay for predicting hemodynamic measures of cardiac allograft function in heart transplantation. We evaluated BNP levels using a rapid point-of-care assay in 87 stable cardiac transplant recipients who had 237 consecutive measurements along with endomyocardial biopsy, right-sided cardiac catheterization, and echocardiography. Using median tendencies, 2 groups were identified: the low BNP group (n = 116, BNP <150 pg/ml) and the high BNP group (n = 121, BNP >/=150 pg/ml). The high BNP group had increased right atrial pressures, higher pulmonary artery systolic pressures, pulmonary capillary wedge pressures, and lower cardiac index. Besides hemodynamic variables, the presence of right ventricular dysfunction (p = 0.05) and significant tricuspid regurgitation (p = 0.003) were associated with higher BNP levels. Independent predictors of BNP levels on multivariate analysis included elevated pulmonary capillary wedge pressure, lower cardiac index, and symptoms of dyspnea and fatigue. This initial investigation establishes the accuracy of a point-of-care BNP assay in predicting cardiopulmonary hemodynamic aberrations despite preserved left ventricular systolic function in heart transplant recipients. Rapid bedside BNP analysis may provide a noninvasive surrogate method for the comprehensive assessment of cardiac allograft function and hemodynamics in heart transplantation.

Discoordinate modulation of natriuretic peptides during acute cardiac allograft rejection in humans

BACKGROUND

Increased circulating levels of the cardiac polypeptide hormones atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) may be observed after orthotopic cardiac transplantation. Both the hypertrophic and inflammatory processes in the allograft may contribute to this increase, but no mechanistic explanation has been suggested for this observation.

METHODS AND RESULTS

Plasma immunoreactive ANF and BNP determinations were performed in 10 consecutive transplant patients. These were correlated with degree of rejection as reflected by histopathological findings at serial endomyocardial biopsies. Three patients had associated hemodynamic measurements and blood samples 24 hours before and after transplantation. All rejection episodes that received treatment were accompanied by a marked increase in BNP plasma levels to > approximately 400 pg/mL. Steadily increasing BNP levels preceded overt rejection as assessed by histopathological criteria. The increase in plasma BNP was not always accompanied by an increase in ANF, which suggests the specific upregulation of BNP gene expression during acute rejection episodes. Treatment of the acute rejection episodes led to a substantial decrease of BNP plasma levels.

CONCLUSIONS

The significant selective increase in plasma BNP levels found in the present study has not been previously described. This finding provides a new insight into the mechanism of allograft rejection and the modulation of natriuretic peptide synthesis and release. Furthermore, although preliminary, the data suggest that BNP plasma levels could form the basis for a new, noninvasive screening test to predict acute cardiac allograft rejection. Because treatment with the antilymphocyte monoclonal antibody OKT3 (murine monoclonal antibody to the CD3 antigen of the human T-cell) decreased BNP plasma levels, cytokine production by T-cells may mediate the selective increase in circulating BNP.