Correlation between plasma B-type natriuretic peptide levels and left ventricular diastolic function using color kinetic imaging.

BACKGROUND: B-type natriuretic peptide (BNP) has been used widely as an objective marker for severity and prognostic predictor of heart failure. Recently it has been reported that plasma BNP level is associated with left ventricular (LV) diastolic dysfunction. Color kinesis (CK), a technique based on acoustic quantification, has been developed to facilitate the evaluation of regional wall motion and LV function. The aim of this study is to investigate the relationship between plasma BNP levels and LV diastolic function using diastolic CK imaging.

METHODS AND RESULTS: The study included 65 subjects in sinus rhythm who were referred for echocardiography to evaluate cardiac function with simultaneous measurements of plasma BNP. Thirty-five patients were in New York Heart Association class I or II, and 15 were in class III or IV. We performed echocardiography with assessment of LV function, including LV ejection fraction (EF), transmitral flow (E/A), early diastolic mitral annular velocity (e'), and diastolic CK. Diastolic CK images, obtained from LV mid-papillary short-axis view, were analyzed using ICK software. The CK-diastolic index (CK-DI) was defined as the calculated LV segmental filling fraction during the first 30% of diastole, expressed as a percentage. The mean CK-DI was determined from the average CK-DI of six segments (anterior, anteroseptal, septal, inferior, posterior, lateral wall). Blood for BNP was collected on the same day as the echocardiographic study. We found significant correlations between mean CK-DI and log BNP (r=-0.66, p<0.0001), whereas log BNP correlated weakly with EF (r=-0.26), E/A (r=0.22), DT (r=-0.15) and E/e' (r=0.41).

CONCLUSION: Our results suggest that the plasma BNP level may be related to LV relaxation. The analysis of diastolic CK may be useful for quantitative assessment of LV diastolic function in patients with heart failure.