Abstract 13588: New Index Derived From 3-Dimensional Speckle Tracking Echocardiography for the Estimation of Left Atrial Pressure

Abstract

Background: The ratio of the early diastolic transmitral flow velocity to mitral annular velocity (E/e’) is clinically useful to assess mean left atrial (LA) pressure. However, its use is limited to patients with regular rhythm because E and e’ cannot be obtained from the same beat. Moreover, it has been reported not reliable in patients with preserved ejection fraction or healthy subjects. Recently, 3-dimensional (3D) speckle tracking echocardiography has allowed us to measure left ventricular (LV) volume through one cardiac cycle. Assuming that mitral valve area does not change during diastole, the early filling rate derived from the time derivative of LV volume ([dV/dt]e) could substitute for E. Global early diastolic strain rate (SRe) calculated from all LV segments, which is simultaneously acquired with [dV/dt]e, reflects global LV relaxation more accurately than e’. Therefore the ratio of both parameters ([dV/dt]e/SRe) may be able to substitute for E/e’. We investigated whether this novel parameter can estimate mean LA pressure in an animal experiment using healthy dogs.

Methods: In 8 healthy dogs, hemodynamic conditions were varied by esmolol infusion and saline or dextran infusion. 3D full volume images were acquired in each condition with volume rate of 35.2 volumes/s (Artida, Toshiba). Parameters [dV/dt]e and global SRe were obtained from the same beat and semi-automatically analyzed by 3D speckle tracking software. Global SRe was measured from radial, circumferential, and longitudinal strain. E/e’ was also measured by conventional 2-dimensional echocardiography. LA and LV pressures were recorded by micromanometers.

Results: A strong positive correlation was observed between [dV/dt]e and E (r = 0.74, p < 0.0001). Global circumferential SRe was significantly correlated with time constant of LV pressure decay (τ) (r = -0.85, p < 0.0001) whereas global radial and longitudinal SRe and e’ were weakly correlated. Mean LA pressure was significantly correlated with [dV/dt]e/SRe derived from circumferential strain (r = 0.58, p = 0.01) , but not correlated with conventional E/e’ (r = -0.25, p = 0.35).

Conclusions: The novel parameter [dV/dt]e/SRe may allow more accurate estimation of LA pressure in healthy subjects compared to conventional E/e’.