Can the left ventricular early diastolic tissue-to-blood time interval be used to identify a normal pulmonary capillary wedge pressure?

The pulsed Doppler early diastolic left ventricular (LV) tissue (e)-blood (E) onset temporal relationship (e-E) is suggested to predict pulmonary capillary wedge pressure (PCWP), through the formulas: tau = 32 + 0.7(e-E) and PCWP = LV end-systolic pressure x e(-IVRT/tau). Small changes/errors in E could influence the quotient IVRT/tau by oppositely affecting IVRT and e-E. At rest in 50 healthy individuals we noted: e-E: 2 +/- 14 ms; IVRT: 89 +/- 17 ms; calculated tau: 33 +/- 10 ms; and PCWP: 9 +/- 9 mmHg (> 12 mmHg in 28%). Non-pharmacological preload alterations in 14 individuals rendered an intraindividual 'PCWP'-fluctuation of up to 40 mmHg. This application may therefore not be clinically robust.