The Value Of Plasma NT-proBNP Level For The Diagnosis Of Diastolic Heart Failure In Hypertensive Patients

ObjectiveTo investigate the relations of plasma NT-proBNP level with clinical severity, and echocardiographie parameters of diastolic dysfunction in patients with essential hypertension, and try to get the cut-off value of plasma NT-proBNP for the diagnosis of diastolic heart failure(DHF).Methods88 patients with essential hypertension and normal systolic function were selected for the study. Patients without congestive heart failure(CHF) and diastolic dysfunction were classified as group I,patients without CHF but with diastolic dysfunction were classified as group II and patients with both CHF and diastolic dysfunction were classified as group III. 20 healthy subjects were selected as control goup. Heart function was classified as NYHA class I toâ…£according to clinical data. Diastolic function, measured by Doppler echocardiogniphic within 24 hours after admission, was classified as normal, impaired relaxation, pseudonormal, and restrictivelike filling patterns. Plasma NT-proBNP level was measured within 24 hours after admission. The plasma level of NT -proBNP was compared respectively in study groups, and the relationships of plasma NT-proBNP level with diastolic disfunctional grades and NYHA classifications were analysed. ROC curves were established to determine the optimal cut-off values of plasma NT-proBNP for identifying diastolic dysfunction and diastolic heart failure in hypertensive patients.Results1. Plasma NT-proBNP levels were 42.05(6-85) pg/ml in control group;117 (30-258) pg/ml in group I;212.50 (72-378) pg/ml in group II and 1100.19 (150-5327) pg/ml in groupmâ…¢respectively,there were significant differences between groups (P<0.05).2. Plasma NT-proBNP level was correlated with the severity of diastolic dysfunction (r=0.887,P<0.01), the concentration was 81.31 (6.0-258.0) pg/ml in grade I; 257.29 (72.0-486.0) pg/ml in grade II; 689.29 (294.0-1104.0) pg/ml in grade III and 2596.27(1242.0-5327.0) pg/ml in gradeâ…£, there were significant differences between grades (P<0.01).3. Plasma NT-proBNP level was correlated with the NYHA-classification in hypertensive patients(r=0.831,P<0.01),NT-proBNP concentration was 42.05(6.0-85.0)pg/ml in control group, 166.83(30-378)pg/ml in patients with class I,539.88(550-1104)pg/ml in patients with class II,1232.7(192-3619)pg/ml in class III and 2615.5(1404-5327)pg/ml in classâ…£, there were significant difference between patients with different NYHA classifications (P<0.05).4. Plasma NT-proBNP level in patients with left ventricular hypertrophy was 973.034(60.0-5327.0)pg/ml, higher than that of patients with normal LVMI [740.243(6.0-3481.0)pg/ml,P<0.01], NT-proBNP level was correlated with LVMI in hypertensive patients(r=0.341, P<0.002).5.The area under the curve(AUC) was 0.960 (95%CI 0.903-0.988, P<0.001), as the ROC curve of plasma NT-proBNP level for defining diastolic disfunction was established. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value(NPV)of plasma NT-proBNP level for defining diastolic dysfunction were 83.3%, 95.24%, 96.5% and 78.4% respectively when the cut-off value was 186pg/ml.6. The AUC was 0.977(95%CI0.927-0.996,P<0.001). as the ROC curve of plasma NT-proBNP level for the diagnosis of DHF was established. The sensitivity,specificity, PPV and NPV of plasma NT-proBNP level for diagnosis of DHF were 90.5%, 97%, 95.0% and 94.1% respectively, when the cut-off value was 286pg/ml.ConclusionsPlasma NT-proBNP level was correlated with the severity of diastolic dysfunction in patients with essential hypertention. NT-proBNP concentration increased with increasing of diastolic disfunction grades and NYHA classifications. The plasma NT-proBNP levels in patients with left ventricular hypertrophy was higher than that in patients with normal LVMI. When the optimal cut-off value was established, diastolic disfunction can be diagnosed specifically and sensitivitily according to plasma NT-proBNP level. Therefore, plasmal NT-proBNP level is a simple and valuable parameter for the diagnosis of DHF. Key words:NT-proBNP; diastolic heart failure ; hypertension; lefe ventricular...