The relationship between the time interval difference of isovolumic relaxation (T[IVRT-IVRTa]) and serum levels of N-terminal pro-brain natriuretic peptide in patients with intermediate E/Ea ratio

Abstract

Introduction: The ratio of early diastolic transmitral velocity to early mitral annular diastolic velocity (E/Ea) can be used to group patients according to filling pressures. However this relationship has not been validated in the intermediate group (E/Ea = 8-15). The time difference between the onset of E and Ea also correlates with left ventricular (LV) filling pressures. The purpose of our study was to evaluate the correlation between the time interval difference of isovolumic relaxation (T[IVRT-IVRTa]) and N-terminal pro-brain natriuretic peptide (NTpro-BNP) in patients with an intermediate E/Ea ratio.

Methods: Echocardiography was performed simultaneously with NTpro-BNP measurement in 60 consecutive patients who had an intermediate E/Ea and were in sinus rhythm. Ea and the isovolumic relaxation time (IVRTa) at the septal and lateral sites of the mitral annulus were measured using pulsed tissue Doppler and the average was utilised. Pulsed Doppler was used to measure E and IVRT. E/Ea and IVRT-IVRTa (T[IVRT-IVRTa]) were calculated.

Results: We demonstrated significant correlations between T[IVRT-IVRTa] and NTpro-BNP (r = -0.72, p<0.001), maximal systolic velocity of the mitral annulus (Sa: r = -0.50, p < 0.001), pulmonary artery systolic pressure (r = 0.42, p = 0.002), IVRTa (r = -0.27, p = 0.03), LV ejection fraction (LVEF: r = -0.26, p = 0.04), IVRT (r = -0.24, p = 0.04). We were unable to demonstrate significant relationships between NTpro-BNP and E deceleration time, left atrial diameter/area/volume, Ea or E. By a multiple linear regression analysis, including T[IVRT-IVRTa], IVRT, IVRTa, E/Ea, LVEF, pulmonary artery systolic pressure and Sa as potential determinants, TIVRT-IVRTa (= -0.57, p < 0.001) was shown to be the best independent predictor of NTpro-BNP (r 2 = 0.68, p < 0.001).

Conclusions: T[IVRT-IVRTa] correlates strongly with NTpro-BNP levels in patients with intermediate E/Ea, and could be used as a simple echocardiographic index, with reasonable accuracy.