Study On The Relationship Between Brain Natriuretic Peptide And Renal Function In Patients With Congestive Heart Failure

Objective: This study sought to evaluate the relationship between brain natriuretic peptide (BNP), renal function, and the severity of congestive heart failure (CHF)Materials and Methods: We selected 283 patients with CHF according to the NYHA class. We measured the plasma URIC,plasma BNP level. Estimated glomerular filtration rate(eGFR) by the Cockcroft-Gault equation was used as an indicator of renal function. We divide the patients into 4 groups according to the NYHA class or GFR class, and analyses the plasma BNP varies; We also divide the patients into 2 groups according to the National Kidney Foundation Practice Guidelines, and analyses the plasma BNP varies.Results:1. Comparison of BNP values in five pathogenesis groupsThe BNP values in CHD group(group1), DCM group(group2), hypertension group(group3), rheumatic heart disease group(group4) and congenital heart disease group(group5) are 233.8±89.4 pg/ml,285.3±112.4 pg/ml,258.5±100.4 pg/ml,217.6±110.4 pg/ml,296.9±167.5 pg/ml respectively, but there was no significantly difference been found between them(p>0.05).2. Comparison of BNP values in four NYHA class groupsThe plasma level of BNP in NYHAI (group1), NYHAII (group2), NYHAIII (group3) and NYHAIV (group4)are 45.3±11.1 pg/ml,69.3±18.2 pg/ml,145.6±49.9 pg/ml,322.5±101.1 pg/ml. The BNP values were increases follows the NYHA class, and BNP value in NYHAIV group was significantly higher than other groups (P<0.01). The difference between 4 groups was regarded as significant (P<0.01).3. Comparison of BNP values in four renal function class groupsThe plasma level of BNP in eGFR≥90(group1),60≤eGFR<90(group2),40≤eGFR<60 (group3),eGFR<40(group4) is 109.4±71.0 pg/ml,154.7±110.0 pg/ml,227.8±161.3 pg/ml,281.4±176.5 pg/ml respectively. The BNP values were increases follows the eGFR class(P<0.01). And the difference between 4 groups was regarded as significant(P<0.01).4. Interaction between NYHA functional class and renal function on BNP①We divided the patients into16 groups according to the NYHA functional class and renal function: NYHAI and eGFR≥90, NYHAI and eGFR≥90, NYHAIII and eGFR≥90, NYHAIV and eGFR≥90, NYHAI and 60≤eGFR<90,NYHAII and 60≤eGFR<90, NYHAIII and 60≤eGFR<90, NYHAIV and 60≤eGFR<90, NYHAI and 40≤eGFR<60, NYHAII and 40≤eGFR<60, NYHAIII and 40≤eGFR<60, NYHAIV and 40≤eGFR<60, NYHAI and eGFR<40, NYHAII and eGFR<40, NYHAIII and eGFR<40, NYHAIV and eGFR<40. We analysis the effect on BNP.②The result shows that plasma level of BNP was increased with the severity of CHF and was also independently affected by the degree of renal function (P<0.01, on two-way analysis of variance). In the same renal function class, the plasma level of BNP was increased with the severity of CHF(P<0.01); in the same NYHA class, plasma level of BNP was increased with the severity of renal function(P<0.01), and the more severity of CHF ,the more significant this tendency is. In the patients of NYHAIV class, the plasma BNP levels were approximately two-fold greater in patients with an GFR<40 compared with that in patients with an eGFR≥90.5. Spearman rank correlation analysisBecause BNP levels were not normally distributed, we use㏒BNP instead of plasma BNP in correlations and regression models. not only NYHA, LVEF and LVEDP but also eGFR and age has correlation with plasma BNP. The correlation Coefficient is NYHA(rs=0.621,P<0.0001)> LVEF(rs=-0.781,P<0.0001)> LVEDd(rs=0.409,P<0.0001)> eGFR(rs=-0.363,P<0.0001)> age(rs=0.246,P<0.0001). The gender was not significantly correlate with the㏒BNP(rs=-0.056,P=0.196).6. Stepwise regressionIn the stepwise regression about㏒ BNP and its relative factors, taking age, gender, NYHA, eGFR, LVEF and LVEDd as variables. Set Pin=0.05,Pout=0.10. NYHA(X1),eGFR(X2),LVEF(X3),LVEDd(X4)were positively correlated with LogBNP. The regression equation is Y=3.069+0.563X1-0.32X2-0.06X3-0.33X4. NYHA were positively correlated with㏒ BNP, LVEDd, eGFR ,LVEF were negative correlation with㏒ BNP.7. Comparison of BNP values in renal function normal group and renal function impaired groupIn the NYHAI class, the plasma BNP in patients with eGFR≥60 and eGFR<60 is 41.8±10.4pg/ml,54.0±7.2pg/ml(P<0.01) respectively; In the NYHAII class, the plasma BNP in patients with eGFR≥60 and eGFR<60 is 62.5±17.7pg/ml,79.9±13.3pg/ml(P<0.01) respectively; In the NYHAIII class, the plasma BNP in patients with eGFR≥60 and eGFR<60 is 125.2±29.2pg/ml,217.6±40.3pg/ml(P<0.01) respectively; In the NYHAIV class, the plasma BNP in patients with eGFR≥60 and eGFR<60 is 249.1±67.1pg/ml,416.3±41.8pg/ml (P<0.01) respectively.Conclusion:1.The renal function has correlation with the plasma level of BNP, withing the renal function contaminated, the plasma level of BNP increases gradually; 2. In the same NYHA class, the plasma level of BNP was significantly higher in renal function impaired group than normal one. It indicate that the optimal cutoff for BNP to diagnose CHF should be increased for patients with an eGFR<60.3. Patients with CHF and renal function impaired is very common in clinic, and the eGFR index is fast, simple and cheap. These findings gives us an usefull tool to evaluate patients overall.