Introduction and objectives: The plasma N-terminal probrain natriuretic peptide (NT-proBNP) level is a sensitive marker of ventricular dysfunction. The diagnostic and prognostic value of urinary NT-proBNP measurement has been demonstrated. The objective of this study was to determine the relationship between established parameters of ventricular function and the urinary NT-proBNP level.
Methods: The study involved 74 patients with heart failure (54 male, age 66 [12] years). A Doppler echocardiographic study was performed to measure atrioventricular plane displacement (AVPD), ejection fraction, mitral flow propagation velocity, and E/A. Urinary and plasma NT-proBNP levels, and the plasma aldosterone level were measured.
Results: In the whole group, the plasma NT-proBNP level was 948 (961) pg/mL, the urinary NT-proBNP level was 88.7 (17.8) pg/mL, and the aldosterone level, 165 (145) pg/mL. There were correlations between urinary NT-proBNP level and AVPD (r=-0.5; P< .0001), ejection fraction (r=-0.3; P< .01), and mitral flow propagation velocity (r=-0.24; P< .05). On dividing AVPD and ejection fraction measurements into quartiles, respectively, the urinary NT-proBNP levels for these quartiles were Q1: 103 (28) pg/mL, Q2: 89 (9) pg/mL, Q3: 86 (9) pg/mL, and Q4: 78 (9) pg/mL (P< .0001) and Q1: 101 (26) pg/mL, Q2: 85 (12) pg/mL, Q3: 83 (10) pg/mL, and Q4: 85 (11) pg/mL (P< .05), respectively. Multiple linear regression analysis showed that the plasma NT-proBNP level was an independent predictor of the urinary NT-proBNP level (P< .0001). When the plasma NT-proBNP level was excluded, AVPD and ejection fraction appeared as alternative independent predictors (P< .05).
Conclusions: There is a correlation between the urinary NT-proBNP level and left ventricular function parameters. This study supports the use of the urinary NT-proBNP level as a biochemical marker of ventricular function in heart failure patients.