Background: We hypothesized that the severity of resting perfusion abnormalities assessed by the summed rest score (SRS) would be associated with a higher rate of adverse outcomes in patients with heart failure (HF) and reduced left ventricular (LV) ejection fraction (EF). Methods: A subset of 240 subjects from HF-ACTION underwent resting technetium-99m tetrofosmin-gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). Images were evaluated using a 17-segment model to derive the SRS and additional nuclear variables. Results: After adjusting for prespecified covariates, SRS was significantly associated with the primary end point (hazard ratio 0.98, 95% confidence interval [CI] 0.97-1.00, P = .04), with a higher SRS corresponding to lower risk of an event. This association was not present in the unadjusted analysis. The relationship between SRS and the primary outcome was likely due to a higher event ratein patients with ischemic HF and a low SRS. The LV phase SD was not predictive of the primary outcome (hazard ratio 1.00, 95% confidence interval 0.99-1.01, P = .49). In a post hoc analysis, nuclear variables provided incremental prognostic information when added to clinical information (P = .006). Conclusions: Gated SPECT MPI provides important information in patients with HF and reduced LVEF. In the adjusted analysis, SRS has an unexpected relationship with the primary end point. Phase SD was not associated with the primary end point. Rest-gated SPECT MPI provides incrementally greater prognostic information than clinical information alone. © 2011 Mosby, Inc. All rights reserved.