The impact of myocardial perfusion imaging (MPI) on prediction of risk for future cardiac events was examined by comparing predictions based on clinical information alone and in combination with MPI findings. A 3-cardiologist Cardiac Event Prediction Panel (CEPP) estimated three-year cardiac event (non-fatal MI; aborted sudden cardiac death; cardiac death) risk based on clinical data (C) for 371 subjects. CEPP repeated this estimation after receiving Summed Stress Scores (SSS) and Summed Rest Scores (SRS) from blinded reading of rest-stress 99mTc-tetrofosmin MPI SPECT studies (C + MPI). The C and C + MPI estimates were then compared with three-year and total event rates. MPI was normal (SSS ≤ 3) in 227 patients (61%), mildly abnormal (SSS 4-8) in 31 (8%), moderately abnormal (SSS 9-13) in 36 (10%), and severely abnormal (SSS > 13) in 77 (21%). Eighteen cardiac events occurred within 3 years and 33 occurred during a mean follow-up of 3.9 years. C + MPI estimates of low risk (