Background: The pathophysiology of abnormal relaxation pattern in the transmitral flow (TMF) velocity waveform has not been fully elucidated.
Methods and results: A total of 173 patients who underwent comprehensive Doppler echocardiography and diagnostic cardiac catheterization for coronary artery disease were enrolled in the study. Peak early and late diastolic TMF velocities (E and A, respectively) were measured. Minimum left ventricular (LV) pressure; LV pre-A wave pressure (surrogate of mean left atrial [LA] pressure); time constant (τ) of LV pressure decay; and LV ejection fraction (LVEF) were calculated. Patients with E/A ratio <1.0 and LVEF ≥ 50% were enrolled. Patients with τ ≥ 48 ms and those with τ <48 ms were compared. The 2 groups had no significant differences in E or E/A. Minimum LV pressure (6.9 ± 2.2 mmHg vs. 3.6 ± 2.9 mmHg, P<0.0001) and LV pre-A wave pressure (9.5 ± 2.4 mmHg vs. 6.1 ± 3.0 mmHg, P<0.0001) were significantly higher in patients with τ ≥ 48 ms compared to those with τ <48 ms, but the difference between the LV pre-A and minimum LV pressures was similar between the groups (2.6 ± 1.4 mmHg vs. 2.5 ± 1.5 mmHg, P=0.89).
Conclusions: Proportional elevations in minimum LV and pre-A pressures, due to deteriorated LV relaxation, resulted in no changes in the pressure gradient between the LA and LV in early diastole, E, or E/A.