Differential Impact of Appropriate Use Criteria on the Association between Age and Abnormal Stress Myocardial Perfusion SPECT

Background: The diagnostic and prognostic value of appropriate use criteria (AUC) for coronary artery disease (CAD) is well established. Whether the diagnostic yield of AUC for predicting CAD is preserved among the elderly is not known.

Methods: We analyzed a multisite prospective cohort of 1511 consecutive patients (age 59±13 years, 57% males) who underwent outpatient, community-based single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). Appropriateness of the studies was determined on the basis of the 2013 multimodality AUC for detection and risk assessment of stable ischemic heart disease. Abnormal SPECT MPI was defined by either a summed stress score of 4 or greater or a summed difference score of 2 or greater.

Results: Abnormal SPECT MPI was present in 190 patients (12.5%), while ischemia on MPI alone was present in 122 patients (8%). In multivariate logistic regression analysis, age of 60 years or greater, male sex, hypertension, diabetes mellitus, and known CAD were independent predictors of abnormal SPET MPI, while appropriate indication for testing was not. Age of 60 years or greater was also an independent predictor of inducible myocardial ischemia, while appropriate indication for testing was not. Among the elderly (≥60 years), regardless of appropriateness of testing, there was no difference in the prevalence of abnormal SPECT (19 vs. 14%, P=0.14) or prevalence of SPECT ischemia (11 vs. 11%, P=1.00). Among younger patients, however, appropriate testing predicted a greater prevalence of abnormal SPECT (12 vs. 7%, P=0.013).

Conclusion: In this multisite cohort, testing based on AUC did not discriminate the risk of abnormal SPECT MPI among the elderly. Caution is advised when relying on AUC for referral of elderly patients for SPECT MPI.