Background: A noninvasive estimation of left ventricular (LV) diastolic chamber stiffness (K(LV)) is still a challenge. Experimental data suggests that K(lv) can be obtained by using Doppler mitral flow deceleration time (DT) as the only variable: K(lv) = (70/[DT-20])(2) mm Hg/mL. We assessed the accuracy of this noninvasive estimate of K(lv) by comparing it with invasive measurement of K(lv) in intact patients with a wide range of LV size and function under varying loading conditions.
Methods: Twenty-five patients (age 54 +/- 12 years) with ischemic heart disease (n = 19) or primary LV dysfunction (n = 6), with a wide range of DT (79-324 ms) and ejection fraction (8%-57%), underwent simultaneous assessment of LV pressure by micromanometer and volume by 2-dimensional (2D) echocardiography-guided Doppler mitral flow velocity (where volume = mitral flow velocity integral x annular area) calibrated to 2D echocardiography stroke volume. Invasive K(lv) [delta pressure (from minimum to end-diastolic)/delta volume (during the same time interval)] was obtained at baseline and in 23 patients after LV unloading by prostaglandin E(1) (30-60 ng/kg/min) (n = 12), nitroglycerin (0.2 mg) (n = 9) or magnesium (1 g) (n = 2). Noninvasive K(lv) was estimated according to the above formula.
Results: In this set of patients with normal mitral annular area (3.9 +/- 1.1 cm(2)/m(2)), multivariate analysis showed that DT is inversely related to K(lv) (P <.001) but not to left atrial chamber stiffness, LV volume, relaxation time constant, mitral valve opening pressure, or area. The relation between noninvasively calculated and directly measured K(lv) was close to the line of identity under all conditions, (y = 0.93x + 0.05, r = 0.67, n = 48, P <.001), although with a wide standard error of the estimate (0.26 mm Hg/mL).
Conclusion: We conclude that K(lv) can be calculated +/- 0.5 mm Hg/mL from noninvasively measured DT in patients.