Abstract 1774: The Prognosis of a Normal Stress-Only SPECT Myocardial Perfusion Imaging Study
Objectives: To determine the prognosis of stress-only SPECT MPI in routine clinical practice.
Background: With normal stress perfusion images, rest imaging appears superfluous. Stress-only imaging saves time and radiation exposure. A benign prognosis of normal stress-only imaging has not been validated in a large cohort.
Methods: Patients at lower pre-test risk for CAD presenting for a Tc-99m SPECT MPI over a 26 month period underwent a stress-only protocol (ADAC/Philips, Vantage Pro). If the stress images were normal (with or without attenuation correction), rest images were not performed. All cause mortality was determined using the Social Security Death Index; survival was analyzed using Kaplan-Meier statistics.
Results: A total of 1,797 patients (891 exercise and 906 pharmacologic), follow-up of 22 ± 7 months were analyzed. The exercise cohort was 53% F, 49 ± 11 yrs; the pharma group was 67% F, 58 ± 15 yrs. The exercise capacity was 11 ± 4 METS and 96% had a low and 3% intermediate risk of CAD. The pharma group risk was 80% low and 13% intermediate. The 1 year all-cause mortality was 0.0% in the exercise group and 7.2% in the pharma cohort (p<0.0001). If patients with end-stage kidney or liver disease (n=233) and those with abnormal EF (n=73) were removed from the pharma group, the 1 year mortality was 7.4%.
Conclusions: A negative stress-only exercise SPECT MPI has an excellent 1 year prognosis. However, a negative pharmacologic stress-only study has a high 1 year mortality and deserves further analysis as to the causes of death. This group may have an increased mortality given their higher prevalence of significant comorbities rather than due to misinterpretation of perfusion images.