IVRT'/IVRT Index Is a Useful Tool for Detection of Elevated Left Ventricular Filling Pressure in Patients with Preserved Ejection Fraction

Objective: Deterioration of active relaxation results in prolongation of isovolumteric relaxation time (IVRT), however, when left ventricular filling pressure elevates, mitral valve opens earlier and IVRT shortens. This shortening is not seen when IVRT is measured with tissue Doppler imaging (IVRT′). Then, IVRT′ prolongs with the deceleration of active relaxation independent of left ventricular filling pressure. We hypothesized that IVRT′ reflects the relaxation rate, thus, the ratio of IVRT′ to IVRT may possibly detect left ventricular filling pressure elevation. Methods: The group of 39 subjects (aged 64 ± 5 years) with preserved ejection fraction (EF > 50%) underwent combined echocardiographic and hemodynamic examinations. Echocardiographic parameters of mitral inflow and mitral annular motion were correlated with invasive indices of left ventricular relaxation and filling pressure. Results: Time constant of isovolumetric pressure decline (tau) correlated closely with IVRT′ (r = 0.73, P < 0.001) but not with early diastolic velocity of mitral annulus (E′) (r =−0.207, P = 0.206). The best parameter correlating with M-LVDP was IVRT′/IVRT (r = 0.694, P < 0.001, M-LVDP = 7.7 × IVRT′/IVRT + 5.1). A weaker relation was also noted between the ratio of early mitral peak inflow velocity to early diastolic velocity of mitral annulus (E/E′) and M-LVDP (r = 0.469, P < 0.001). The relationships between standard Doppler parameters and left ventricular diastolic pressures were uniformly poor. Conclusions: The study demonstrated that IVRT′ may serve as a surrogate of left ventricular active relaxation. IVRT′/IVRT index may be applied to estimate left ventricular filling pressure.