Abstract: Cardiac resynchronization therapy(CRT)has shown benefits in patients with advanced heart failure.It has shown with ultrasound cardiogram(UCG)that the presence of left ventricular mechanical dyssynchrony is an important predictor for response to CRT.Therapy trial showed that under present conditions the current available UCG techniques including tissue Doppler imaging(TDI)and myocardial strain-rate imaging are not ready for routine clinical practice to assess left ventricular dyssynchrony.Research now shows that the advantages of gated myocardial perfusion SPECT over TDI are its automation, repeatability, and reproducibility that are very promising in improving prediction of CRT response in heart failure patients.