Improvement of diastolic dyssynchrony by cardiac resynchronization therapy are closely related to the improvement of global diastolic filling

Objectives Here, we describe a novel method for separately evaluating systolic and diastolic LV-DS by using gated myocardial perfusion SPECT (GMP SPECT). The aim of this study is to investigate the reason why improvement of the LV dyssynchrony improve the chronic heart failure.

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. We examined the relation between improvement of systolic dyssynchrony and improvement of the peak ejection rate. We also examined the relation between improvement of diastolic dyssynchrony and improvement of the peak filling rate.

Results The phase-SD values of peak thickening and thinning were significantly lower during CRT-on than during CRT-off. As compared to peak thickening, the phase-SD of peak thinning showed a strong correlation with the serum BNP level. The phase-SD of peak thinning was positively correlated with that in global diastolic filling.

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 global diastolic filling