Correlates and Predictors of NT-proBNP in Life Insurance Applicants

OBJECTIVES

-To document the various laboratory and demographic/historical correlates of NT-proBNP levels in applicants for life insurance, and to explore the accuracy of a prediction model based on those variables.

METHOD

-NT-proBNP blood test results were obtained from 1.34 million insurance applicants between the age of 50 and 85 years, beginning in 2003. Exploratory data analysis was carried out to document correlations with other laboratory variables, sex, age, and the presence of relevant diseases. Further, predictive models were used to quantify the proportion of the variance of NT-proBNP, which can be explained by a combination of these other, easier to determine variables.

RESULTS

-NT-proBNP shows the expected, negative correlation with estimated glomerular filtration rate (eGFR) is markedly higher in those with a history of heart disease and is somewhat higher in those with a history of hypertension. A strong, unexpected, negative correlation between NT-proBNP and albumin was discovered. Of the variables evaluated, a multivariate adaptive regression spline (MARS) model automated selection procedure selected 7 variables (age, sex, albumin, eGFR, BMI, systolic blood pressure, cholesterol, and history of heart disease). Variable importance evaluation determined that age, albumin and eGFR were the 3 most important continuous variables in the prediction of NT-proBNP levels. An ordinary least squares (OLS) model using these same variables achieved a R-squared of 24.7%.

CONCLUSION

-Expected ranges of NT-proBNP may vary substantially depending on the value of other variables in the prediction equation. Albumin is significantly negatively correlated with NT-proBNP levels. The reasons for this are unclear.

The impact of renal function on the prognostic value of N-terminal pro-B-type natriuretic peptide in patients with coronary artery disease

BACKGROUND

The impact of renal function on the prognostic value of N-terminal pro-B-type natriuretic peptide (NT-proBNP) remains unclear in coronary artery disease (CAD). This study sought to investigate the value of using NT-proBNP level to predict prognoses of CAD patients with different estimated glomerular filtration rates (eGFRs).

METHODS

A retrospective analysis was conducted from a single registered database. 2087 consecutive patients with CAD confirmed by coronary angiography were enrolled. The primary endpoint was allcause mortality.

RESULTS

The mean follow-up time was 26.4 ± 11.9 months and death events occurred in 197 cases. The NT-proBNP levels increased with the deterioration of renal function, as well as the optimal cutoff values based on eGFR stratification to predict endpoint outcome (179.4 pg/mL, 1443.0 pg/mL, 3478.0 pg/mL, for eGFR ≥ 90, 60-90 and < 60 mL/min/1.73 m2, respectively). Compared with the routine cut-off value or overall optimal one, stratified optimal ones had superior predictive ability for endpoint in each eGFR group (all with the highest Youden's J statistics). And the prognostic value became weaker as eGFR level decreased (eGFR ≥ 90 vs. 60-90 vs. < 60 mL/min/1.73 m2, odds ratio [OR] 7.7; 95% confidence interval [CI] 1.7-33.9 vs. OR 4.8; 95% CI 2.7-8.5 vs. OR 3.0; 95% CI 1.5-6.2).

CONCLUSIONS

This study demonstrated that NT-proBNP exhibits different predictive values for prognosis for CAD patients with different levels of renal function. Among the assessed values, the NT-proBNP cut-off value determined using renal function improve the accuracy of the prognosis prediction of CAD. Moreover, lower eGFR is associated with a higher NT-proBNP cut-off value for prognostic prediction.

The influence of metabolic syndrome and diabetes mellitus on the N-terminal pro-B-type natriuretic peptide level and its prognostic performance in patients with coronary artery disease

OBJECTIVES

Our aim was to investigate whether the presence of metabolic syndrome (MetS) and diabetes mellitus (DM) influenced the N-terminal pro-B-type natriuretic peptide (NT-proBNP) level and its prognostic performance in coronary artery disease (CAD).

PATIENTS AND METHODS

The present study enrolled a total of 1638 CAD patients. Multivariate regression analyses were carried out to relate NT-proBNP to metabolic components, nondiabetic MetS, DM, and MetS score. Furthermore, we examined the prognostic performance of NT-proBNP in patients with non-MetS, nondiabetic MetS, and DM.

RESULTS

NT-proBNP levels correlated inversely with BMI (β=-0.11, P=0.003) and correlated positively with fasting glucose (β=0.12, P=0.001). There were no significant relationships of NT-proBNP with other metabolic parameters. Compared with non-MetS, the presence of DM significantly increased NT-proBNP levels (P=0.004), whereas nondiabetic MetS did not influence NT-proBNP levels (P=0.954). During the median follow-up of 21 months, 109 all-cause deaths occurred. NT-proBNP levels independently predicted all-cause deaths irrespective of the presence of nondiabetic MetS and DM (Pinteraction=0.43).

CONCLUSION

DM, but not nondiabetic MetS, is associated with higher NT-proBNP levels. NT-proBNP can still predict death in patients with CAD, even with the confounding effect of MetS and diabetes.

The influence of age on the clinical implications of N-terminal pro-B-type natriuretic peptide in acute coronary syndrome

Currently, there are no studies addressing the influence of age on the prognostic information of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in Asian population with acute coronary syndrome (ACS). The purpose of this study was to investigate the prognostic performance of NT-proBNP in Chinese patients with ACS across different age groups. A total of 1512 ACS patients with venous blood NT-proBNP measured were enrolled. Patients were divided into tertiles based on their ages (<61, 61-71, ≥72 years). The median NT-proBNP concentrations in the three groups (T1-T3) were 406, 573, and 1288 pg/ml (p < 0.001), respectively. During a median follow-up of 23 months, 150 all-cause deaths occurred, and 88 (58.7 %) were attributed to cardiovascular cause. NT-proBNP levels are independently associated with mortality in each age group [1st group: HR 2.19 95 % CI (1.17-4.10); 2nd group: HR 1.82 95 % CI (1.04-3.20); 3rd group: HR 1.48 95 % CI (1.09-2.01), P interaction = 0.062]. NT-proBNP improves discrimination and reclassification for mortality beyond thrombolysis in myocardial infarction score in patients of all ages. The optimal NT-proBNP cutoff points for predicting mortality in three age groups are 1511, 2340, and 2883 pg/ml, respectively. In conclusion, NT-proBNP is a valuable biomarker in predicting long-term mortality and provides an improvement in discrimination and reclassification for prognosis in ACS patients of all ages.

Relation Between C-X-C Motif Chemokine Receptor 4 Levels and the Presence and Extent of Angiographic Coronary Collaterals in Patients With Chronic Total Coronary Occlusion

Coronary collateral circulation is an alternative source of blood supply to the myocardium in the presence of chronic total coronary occlusion (CTO). C-X-C motif chemokine receptor 4 (CXCR4) signaling usually contributes to neovascularization. Here, we investigate the relation between CXCR4 levels in peripheral blood CD34+ cells and the formation of angiographic coronary collaterals and determine the risk factors that affect CXCR4 expression in patients with CTO. Demographic, biochemical, and angiographic variables were collected from 324 patients with CTO and 90 negative controls. The presence and extent of collaterals were scored according to the Rentrop scoring system (Rentrop's). CXCR4 levels and plasma biochemical factors were detected. Clinical outcomes were collected during a 12-month follow-up. Results show that low (Rentrop's 0 or 1) and high (Rentrop's of 2 or 3) coronary collateralizations were detected in 183 and 141 patients, respectively. The Rentrop scores were positively correlated with CXCR4 levels in patients with CTO. Patients with low CXCR4 expression exhibited worse clinical outcomes compared with those with high CXCR4 expression. Univariate correlation analysis revealed that age of ≥65 years, women, diabetes, increased plasma level of high-sensitivity C-reactive protein (hs-CRP), and N-terminal brain-type natriuretic peptide were associated with low CXCR4 levels. In conclusion, CXCR4 levels were positively correlated with the presence and extent of angiographic coronary collaterals in patients with CTO. Elder age, women, diabetes, increased plasma level of high-sensitivity C-reactive protein, and N-terminal brain-type natriuretic peptide may be risk factors of CXCR4 expression.

N-Terminal Pro-B-Type Natriuretic Peptide Levels Inversely Correlated With Heart Rate Variability in Patients With Unstable Angina Pectoris

We explored the relationships between heart rate variability (HRV) and levels of N-terminal Pro-B-type natriuretic peptide (NT-proBNP) in patients with unstable angina pectoris (UA).A total of 90 consecutive patients admitted < 48 hours for UA were included. Serum levels of NT-proBNP were measured from blood samples. The cohort was divided into tertiles according to NT-proBNP levels. HRV parameters including SDNN, RMSSD, LF, HF, TP, and VLF were assessed by 24-hour Holter ECG monitoring.The median (IQR) NT-proBNP level was 177.02 (64.76, 740.70) pg/mL. Patients with SDNN < 100 ms had higher levels of NT-proBNP than those with SDNN > 100 ms (P = 0.003). With increasing levels of NT-proBNP, both the 24hour monitoring HRV and night-monitoring HRV showed that SDNN and VLF gradually decreased (P < 0.01), and patients in the NT-proBNP lowest tertile group had higher LF values than the other two groups (P < 0.05); however, no difference was found in RMSSD, HF, and TP. During the daytime, the LF, VLF, and TP values were lower in the NTproBNP highest group compared with the lowest tertile group (P < 0.05). NT-proBNP levels correlated negatively with SDNN (r = -0.314, P = 0.003) and VLF (r = -0.397, P < 0.001) but not with other HRV parameters. Multiple regression analysis showed that serum levels of NT-proBNP remained predictive of SDNN (β = -0.060, P = 0.001) and VLF (β = -0.145, P < 0.001), even after adjustment for confounders.Our study showed that the elevated serum levels of NT-proBNP predict reduced HRV parameters, and the increased NT-proBNP levels combined with decreased HRV represent the degree of neurohormonal dysfunction and may be better prognostic predictors for risk stratification in UA patients.

Effect of natriuretic peptides on cerebral artery blood flow in healthy volunteers

The natriuretic peptides (NPs), atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP), have vasoactive functions that concern humans and most animals, but their specific effects on cerebral circulation are poorly understood. We therefore examined the responsiveness of cerebral arteries to different doses of the natriuretic peptides in animals and humans. We conducted a dose-response experiment in guinea pigs (in vitro) and a double-blind, three-way cross-over study in healthy volunteers (in vivo). In the animal experiment, we administered cumulative doses of NPs to pre-contracted segments of cerebral arteries. In the main study, six healthy volunteers were randomly allocated to receive two intravenous doses of ANP, BNP or CNP, respectively, over 20 min on three separate study days. We recorded blood flow velocity in the middle cerebral artery (VMCA) by transcranial Doppler. In addition, we measured temporal and radial artery diameters, headache response and plasma concentrations of the NPs. In guinea pigs, ANP and BNP but not CNP showed significant dose-dependent relaxation of cerebral arteries. In healthy humans, NP infusion had no effect on mean VMCA, and we found no difference in hemodynamic responses between the NPs. Furthermore, natriuretic peptides did not affect temporal and radial artery diameters or induce headache. In conclusion, natriuretic peptides in physiological and pharmacological doses do not affect blood flow velocity in the middle cerebral artery or dilate extracerebral arteries in healthy volunteers.

Association of serum myeloid cells of soluble triggering receptor-1 level with myocardial dysfunction in patients with severe sepsis

OBJECTIVE

To investigate the association of serum sTREM-1 with myocardial dysfunction in patients with severe sepsis.

METHODS

A total of 85 patients with severe sepsis were divided into severe sepsis group (n = 40) and septic shock group (n = 45). Serum levels of sTREM-1, NT-proBNP, APACHE II score, SOFA score, cardiac index, cardiac function index, global ejection fraction, and left ventricular contractility index were measured on days 1, 3, and 7 after admission to ICU.

RESULTS

Serum sTREM-1 levels of patients with septic shock were significantly higher than those with severe sepsis on days 1, 3, and 7. Serum sTREM-1 was positively correlated with APACHE II scores, SOFA scores, and NT-proBNP. However, The sTREM-1 level was markedly negatively correlated with CI, CFI, GEF, and dP/dt max, respectively. Multiple logistic regression analysis showed that sTREM-1 was independent risk factor to NT-proBNP increasing. The optimal cut-off point of sTREM-1 for detecting patients with myocardial dysfunction was 468.05 ng/mL with sensitivity (80.6%) and specificity (75.7%). There is no difference in TREM-1-mRNA expression between the two groups.

CONCLUSIONS

Serum sTREM-1 is significantly associated with myocardial dysfunction and may be a valuable tool for determining the presence of myocardial dysfunction in patients with severe sepsis.