Stress-only Tc-99m SPECT MPI saves time and reduces radiation exposure while a normal study has a benign prognosis. However, no guidelines exist as to which patients should undergo stress-first MPI. The purpose of this study was to validate a previously published pre-test prediction scoring model and refine the stress-first triage process further if possible. We retrospectively reviewed all patients who underwent an attenuation-corrected Tc-99m SPECT MPI over a 39-month period. Based on 17-segment model semi-quantitative scoring, a successful stress-first MPI was defined as a summed stress attenuation-corrected score ≤ 1. Based on results from multivariate analysis, the previously published prediction score (comprised eight clinical and demographic variables) was compared to triage based on coronary artery disease (CAD) status alone and with the addition of other highly associated variables. Logistic regression and Chi-squared analyses were used to determine the magnitude of variable effect and to compare model results. A total of 2,277 patients were included, and the prediction score successfully stratified patients into low-risk (91.1% successful stress-first), intermediate-risk (79.4%), and high-risk (50.7%) groups. Comparing the use of the prediction score to the use of a history of CAD as the only triage factor, 69.0% of patients would be accurately triaged using the prediction score with a cutoff of 7 (maximized sensitivity and specificity), while 78.6% were correctly triaged with CAD status alone (P