Practical implications of current natriuretic peptide research

NT-pro-BNP levels in patients with acute pulmonary embolism are correlated to right but not left ventricular volume and function

N-terminal pro-Brain Natriuretic Peptide (NT-pro-BNP) is primarily secreted by left ventricular (LV) stretch and wall tension. Notably, NT-pro-BNP is a prognostic marker in acute pulmonary embolism (PE), which primarily stresses the right ventricle (RV). We sought to evaluate the relative contribution of the RV to NT-pro-BNP levels during PE. A posthoc analysis of an observational prospective outcome study in 113 consecutive patients with computed tomography (CT)-proven PE and 226 patients in whom PE was clinically suspected but ruled out by CT. In all patients RV and LV function was established by assessing ECG-triggered-CT measured ventricular end-diastolic-volumes and ejection fraction (EF). NT-pro-BNP was assessed in all patients. The correlation between RV and LV end-diastolic-volumes and systolic function was evaluated by multiple linear regression corrected for known con-founders. In the PE cohort increased RVEF (β-coefficient (95% confidence interval [CI]) –0.044 (± –0.011); p<0.001) and higher RV enddiastolic-volume (β-coefficient 0.005 (± 0.001); p<0.001) were significantly correlated to NT-pro-BNP, while no correlation was found with LVEF ( β-coefficient 0.005 (± 0.010); p=0.587) and LV end-diastolic-volume (β-coefficient –0.003 (± 0.002); p=0.074). In control patients without PE we found a strong correlation between NT-pro-BNP levels and LVEF ( β-coefficient –0.027 (± –0.006); p<0.001) although not LV enddiastolic-volume (β-coefficient 0.001 (± 0.001); p=0.418). RVEF (β-co-efficient –0.002 (± –0.006); p=0.802) and RV end-diastolic-volume (β-coefficient <0.001 (± 0.001); p=0.730) were not correlated in patients without PE. In PE patients, lower RVEF and higher RV end-diastolic-volume were significantly correlated to NT-pro-BNP levels as compared to control patients without PE. These observations provide patho-physiological ground for the well-known prognostic value of NT-pro-BNP in acute PE.

Natriuretic peptides in the management of solid organ transplantation associated acute kidney injury: a systematic review and meta-analysis

Randomized controlled trials involving natriuretic peptide administration in solid organ transplantation setting have shown inconsistent effects for renal endpoints. We conducted a systematic review and meta-analysis of these trials to ascertain the role of natriuretic peptides in the management of solid organ transplantation associated acute kidney injury (AKI). MEDLINE, EMBASE, and Google scholar were searched independently by two authors for randomized trials evaluating renal effects of natriuretic peptides in solid organ transplantation settings. Two reviewers independently assessed the studies for eligibility and extracted the relevant data. The pooled estimate showed that natriuretic peptide administration is associated with a reduction in AKI requiring dialysis (odds ratio = 0.50 [0.26–0.97]), a statistically nonsignificant trend toward improvement in posttransplant creatinine clearance (weighted mean difference = 5.5 mL/min, [−1.3 to 12.2 mL/min]), and reduction in renal replacement requirement duration (weighted mean difference −44.0 hours, [−60.5 to −27.5 hours]). There were no mortality events and no adverse events related to natriuretic peptides. In conclusion, administration of natriuretic peptides in solid organ transplantation may be associated with significant improvements in renal outcomes. These observations need to be confirmed in an adequately powered, prospective multicenter study.

Multiple biomarkers and risk of clinical and subclinical vascular brain injury: the Framingham Offspring Study

BACKGROUND

Several biomarkers have been individually associated with vascular brain injury, but no prior study has explored the simultaneous association of a biologically plausible panel of biomarkers with the incidence of stroke/transient ischemic attack and the prevalence of subclinical brain injury.

METHODS AND RESULTS

In 3127 stroke-free Framingham offspring (age, 59±10 years; 54% female), we related a panel of 8 biomarkers assessing inflammation (C-reactive protein), hemostasis (D-dimer and plasminogen activator inhibitor-1), neurohormonal activity (aldosterone-to-renin ratio, B-type natriuretic peptide, and N-terminal proatrial natriuretic peptides), and endothelial function (homocysteine and urinary albumin/creatinine ratio) measured at the sixth examination (1995-1998) to risk of incident stroke/transient ischemic attack. In a subset of 1901 participants with available brain magnetic resonance imaging (1999-2005), we further related these biomarkers to total cerebral brain volume, covert brain infarcts, and large white-matter hyperintensity volume. During a median follow-up of 9.2 years, 130 participants experienced incident stroke/transient ischemic attack. In multivariable analyses adjusted for stroke risk factors, the biomarker panel was associated with incident stroke/transient ischemic attack and with total cerebral brain volume (P<0.05 for both) but not with covert brain infarcts or white-matter hyperintensity volume (P>0.05). In backward elimination analyses, higher log-B-type natriuretic peptide (hazard ratio, 1.39 per 1-SD increment; P=0.002) and log-urinary albumin/creatinine ratio (hazard ratio, 1.31 per 1-SD increment; P=0.004) were associated with increased risk of stroke/transient ischemic attack and improved risk prediction compared with the Framingham Stroke Risk Profile alone; when the <5%, 5% to 15%, or >15% 10-year risk category was used, the net reclassification index was 0.109 (P=0.037). Higher C-reactive protein (β=-0.21 per 1-SD increment; P=0.008), D-dimer (β=-0.18 per 1-SD increment; P=0.041), total homocysteine (β=-0.21 per 1-SD increment; P=0.005), and urinary albumin/creatinine ratio (β=-0.15 per 1-SD increment; P=0.042) were associated with lower total cerebral brain volume.

CONCLUSION

In a middle-aged community sample, we identified multiple biomarkers that were associated with clinical and subclinical vascular brain injury and could improve risk stratification.

Plasma brain natriuretic peptide is associated with hepatic veno-occlusive disease and early mortality after allogeneic hematopoietic stem cell transplantation

Fluid retention is characteristic of veno-occlusive disease (VOD). We hypothesized that plasma brain natriuretic peptide (BNP), a neurohormone secreted in response to volume expansion, may be associated with VOD after hematopoietic stem cell transplantation (HSCT). BNP was measured before and weekly after HSCT in 46 recipients. Sixteen patients developed VOD. BNP concentrations were similar before and on day 0 in patients with and without VOD, but were significantly higher on day 7 and later in those with VOD. Patients with VOD had significantly higher peak BNP concentrations before engraftment than those without VOD (median, 634.4 versus 80.9  pg  ml⁻¹; P=0.01). Multivariate analysis showed that VOD was independently associated with BNP elevation (odds ratio, 50.1; 95% CI: 5.2-478.4; P<0.01). Landmark analysis at day 7 showed that patients with peak BNP concentration of ≥ 180  pg  ml⁻¹ had significantly worse 100-day survival than patients with peak BNP <180  pg  ml⁻¹ (54 versus 91%; P<0.01). In multivariate analysis, BNP elevation before day 7 significantly predicted 100-day survival (hazard ratio 5.3; 95% CI: 1.1-24.3; P=0.03). These findings suggest that plasma BNP may serve as a diagnostic and prognostic marker of VOD.

PROTECTING THE PUMP: Controlling Myocardial Inflammatory Responses

Because of the anatomy, function, and nonregenerative nature of the myocardium, inflammation in this tissue is not well tolerated. Nevertheless, various diseases of the heart are characterized by inflammatory responses involving the effector mechanisms of innate and adaptive (lymphocyte-dependent) immunity. The innate immune response to ischemia-reperfusion injury is, by far, the most common cause of myocardial inflammation. Innate responses may have beneficial influences that preserve myocardial function in the short term but may be maladaptive in chronic states. Adaptive responses in the myocardium occur with infection or loss of tolerance, and lead to myocarditis. Given the narrow margin for benefit of cardiac inflammation, special regulatory mechanisms likely raise the threshold, compared to other tissues, for the induction and persistence of adaptive immune responses. These mechanisms include strong central and peripheral T cell tolerance to heart antigens and induction of anti-inflammatory feedback mechanisms involving cytokines such as interferon-gamma.

Nurse-recorded clinic and ambulatory blood pressures correlate equally well with left ventricular mass and carotid intima-media thickness

OBJECTIVE

To assess relationships between noninvasive ambulatory blood pressure (BP), clinic BP (mean value of three readings in the seated position measured by nurses), structural cardiac indices, intima-media thickness of the common carotid artery and several hormones.

DESIGN

Cross-sectional study of 75 subjects with hypertension and left ventricular hypertrophy (HTH) according to echocardiography, 35 subjects with hypertension and normal left ventricular dimensions (HT) and 23 normotensive subjects (NT).

RESULTS

We found an excellent correlation between mean 24-h ambulatory BP and clinic BP, the r-value for systolic BP being 0.82 and for diastolic levels 0.78 (both P < 0.0001). Clinic and ambulatory BP correlated equally well with left ventricular (LV) mass index (r-values between 0.55 and 0.64, all P < 0.0001) and to intima-media thickness of the carotid artery (r = 0.18-0.34, P < 0.01). The systolic white-coat effect (clinic BP - day-time BP) was higher in the HTH and HT compared with NT and was weakly correlated to LV mass index (r = 0.18, P = 0.04). Nondippers (mean arterial night/day BP ratio of > 0.9) had higher brain (6.1 +/- 7.5 pmol L(-1) vs. 3.7 +/- 3.2 pmol L(-1), P = 0.01) and atrial (14 +/- 3.4 pmol L(-1) vs. 9.3 +/- 5.4 pmol L(-1), P = 0.04) natriuretic peptide levels, and also exhibited a lower ejection fraction (49 +/- 8% vs. 57 +/- 9%, P = 0.006), than dippers.

CONCLUSION

Clinic BP recordings performed by nurses as three measurements 1 min apart provide excellent relationship to target organ damage. Nondippers exhibited signs of a more advanced hypertensive organ damage than dippers which corresponds well with the poor prognosis linked to this condition.

Synthetic Human α-Atrial Natriuretic Peptide Improves the Management of Postoperative Hypertension and Renal Dysfunction after the Repair of Abdominal Aortic Aneurysm

OBJECTIVE

Delayed hypertension (HT) and renal dysfunction (RD) are observed after aortic operations accompanied by infra-renal aortic cross-clamping (AXC). Atrial natriuretic peptide (ANP) has effects on vasodilation and renal protection, and we examined the hypothesis that synthetic human alpha-ANP (hANP) improves the postoperative management for abdominal aortic aneurysm (AAA).

METHODS

Fifty patients undergoing elective aneurysmectomy for infrarenal-AAA between 1998 and 2001 (M:F = 43:7, mean age 70.5 +/- 7.7 years) were randomly allocated to one of 2 groups; Group H (n = 24) received hANP immediately after operation (initial dose: 0.025 microg/kg/min), and Group C (n = 26) served as a control group.

RESULTS

All patients in Group C required nicardipine hydrochloride (4.41 +/- 1.68 mg/h) for prevention of postoperative HT, whereas only 6 patients in Group H required the increase in hANP dose due to HT (P < 0.0001). Maximum hANP dose was 0.035 +/- 0.019 microg/kg/min. Group H showed significantly smaller furosemide dosage in the initial 3 days (H vs. C; 9.2 +/- 11.0 vs. 58.8 +/- 41.5 mg, P < 0.0001), significantly lower peak-Crn (H vs. C; 1.16 +/- 0.53 vs. 2.58 +/- 1.42 mg/dL, P < 0.0001), and significantly lower plasma renin-activity (7.09 +/- 2.38 vs. 11.52 +/- 4.89 ng/mL/h, P = 0.0002) and aldosterone (51.6 +/- 12.7 vs. 81.2 +/- 34.2 pg/mL, P = 0.0002) on the first postoperative day than Group C did.

CONCLUSIONS

These results imply that renin-angiotensin system may play a role in the incidence of postoperative HT and RD, and suggest that hANP infusion is a simple, reliable, and effective method for management during the immediate period after AAA operations.