Global diastolic strain rate for the assessment of left ventricular relaxation and filling pressures

BACKGROUND - Diastolic strain rate (SR) measurements that comprise all left ventricular (LV) segments are advantageous over myocardial velocity for assessment of diastolic function. Mitral early diastolic velocity (E)/SR ratio during the isovolumetric relaxation (IVR) period can be used to estimate LV filling pressures. METHODS AND RESULTS - Simultaneous echocardiographic imaging and LV pressure measurements (7F catheters) were performed in 7 adult dogs. Loading conditions were altered by saline infusion and caval occlusion, and lusitropic state was changed by dobutamine and esmolol infusion. A curve depicting global SR was derived from each of the 3 apical views, and SR was measured during IVR (SRIVR) and early LV filling (SRE). SRIVR had a strong correlation with time constant of LV pressure decay during the IVR period (τ) (r=-0.83, P<0.001), whereas SRE was significantly related to LV end-diastolic pressure (r=0.52, P=0.005) in the experimental stages where τ was <40 ms. In 50 patients with simultaneous right heart catheterization and echocardiographic imaging, mitral E/SRIVR ratio had the best correlation with mean wedge pressure (r=0.79, P<0.001), as well as in 24 prospective patients (r=0.84, P=0.001). E/SRIVR was most useful in patients with ratio of E to mitral annulus early diastolic velocity (E/Ea ratio) 8 to 15 and was more accurate than E/Ea in patients with normal ejection fraction and regional dysfunction (both P<0.01). CONCLUSIONS - Global SRIVR by 2-dimensional speckle tracking is strongly dependent on LV relaxation. E/SRIVR can predict LV filling pressures with reasonable accuracy, particularly in patients with normal ejection fraction and in those with regional dysfunction.