Improvement of LV diastolic filling is the important determinant in treatment of heart failure with CRT

Objectives Left ventricular dyssynchrony (LV-DS) is one of the most important abnormalities in patients with severe heart failure. However, little is known about the clinical significance of systolic LV-DS and diastolic LV-DS.Here, we describe a novel method for separately evaluating systolic and diastolic LV-DS by using gated myocardial perfusion SPECT (GMP SPECT).

Methods The data for GMP SPECT were obtained for 30 patients with CRT or CRT-D during CRT-on and CRT-off (self beats). Short-axis DICOM images were transferred to a personal computer. Peak counts were obtained at every 8° from the short-axis images. Time course of counts were fitted with third harmonic Fourier approximation at each pixel. Phases of peak thickening and early peak thinning were calculated from the first derivative of the fitted curve. Further, standard deviation of phase (Phase-SD) for peak thickening and early peak thinning was also calculated. Global LV peak filling rate was assessed by QGS analysis.

Results As compared to peak thickening, the phase-SD of peak thinning showed a strong correlation with the serum BNP level. Change of the serum BNP level was correlated with the change of early diastolic filling rate (r=0.68, P<0.01), but was not correlated with the change of systolic ejection rate (r=0.44, n.s.).

Conclusions In a clinical setting, diastolic dyssynchrony may be a more important determinant than systolic dyssynchrony for the treatment of heart failure with CRT. The correction of diastolic LV-DS by cardiac re-synchronization therapy might improve heart failure via improvement of the early diastolic filling