Figure 8: (A) A patient without dyssynchrony on gated SPECT. Synchronous onset of contraction is shown on relatively uniform phase angle distribution (left) and tight width and highly peaked histogram (right). At 6 month after CRT, no improvement in NYHA functional class was observed and LVEF remained unchanged (32%→33%). (B) A patient with apparent dyssynchrony on gated SPECT. LV dyssynchrony is demonstrated by heterogeneous phase angle distribution of polar map (left) and wide histogram width (right). At 6 month after CRT, NYHA functional class improved (III→II), with increase in LVEF (21%→33%) (Fig. 7). Left ventricular dyssynchrony was analyzed using Quantitative Gated SPECT software (Cedars-Sinai Medical Center, LA, USA) [48].