Echocardiographic evaluation of systolic and diastolic function: a preoperative study of correlation with serum NT-proBNP.

Abstract

The authors hypothesized that preoperative N-terminal probrain natriuretic peptide (NT-proBNP) correlates well with longitudinal strain measurements and with Doppler measurements of diastolic function.
Prospective observational study.
University teaching hospital.
Forty patients undergoing elective cardiac surgery.
Aortic valve replacement, coronary artery bypass grafting, or a combination of these procedures.
Plasma NT-proBNP concentration was obtained by analyzing blood samples with a commercially available kit. Left ventricular systolic function was assessed by speckle tracking ultrasound strain measurements and left ventricular diastolic function was assessed by 2 Doppler methods: E/A ratio and E/E' ratio. Tissue Doppler imaging velocities (E' and A') were measured in the basal septum (annular) and pulse-wave Doppler was used to measure mitral in-flow profile (E and A). The correlation between global strain data from the speckle tracking ultrasound measurement and NT-proBNP levels was ρ = 0.35 (p = 0.026). With a cutoff value of -15% in global strain measurements, there was a significant difference in NT-proBNP levels (117 v 57 pg/mL, p = 0.048). E/E' values correlated with NT-proBNP levels (ρ = 0.46, p = 0.011). With a cutoff of 15 in E/E' values, there were significant differences in corresponding NT-proBNP levels (33 v 113 pg/mL, p = 0.004).
A correlation was found between plasma levels of NT-proBNP and speckle tracking ultrasound strain measurements by an easily employed method applicable in the anesthesia and preoperative settings. In addition, the well-established marker of diastolic function, E/E', correlated well with NT-proBNP, whereas the E/A ratio failed to show any association.