Conventional selection criteria are not consistently able to discriminate between responders and non-responders to cardiac resynchronization therapy (CRT). The objective of this study was to evaluate the usefulness of quantitative gated single-photon emission computed tomography (SPECT) in predicting the response to CRT. This prospective cross-sectional study included 25 patients with advanced congestive heart failure who underwent quantitative gated SPECT before and after CRT implantation. Patients with the left ventricular (LV) lead positioned at the latest activation segment away from the scar had a significantly higher chance of responding than those with the lead positioned at a different area. Responders were likely to have a phase standard deviation (PSD) value of >33°, with 86.6% sensitivity and 90% specificity, and a phase histogram bandwidth (PHB) value of >153°, with 100% sensitivity and 80% specificity. Quantitative gated SPECT can help refine patient selection for CRT implantation, using PSD and PHB cutoff points, in addition to guiding the positioning of the LV lead.