Impact of Appropriate Use on the Estimated Radiation Risk to Men and Women Undergoing Radionuclide Myocardial Perfusion Imaging

UNLABELLED: The impact of appropriate use criteria (AUC) for myocardial perfusion imaging (MPI) with SPECT on the estimated lifetime attributable risk (LAR) of cancer is unknown. METHODS: A cohort of 1,511 consecutive patients who underwent clinically indicated (99m)Tc-setamibi MPI were categorized into appropriate/uncertain (n = 823) versus inappropriate (n = 688) use groups according to the 2009 AUC and were prospectively followed for 27 ± 10 mo. Logistic regression models were used to determine the annualized probability of major adverse cardiac events (MACE) of cardiac death or myocardial infarction and the probability of revascularization within 6 mo of MPI, accounting for relevant covariates. We determined LAR for each subject on the basis of accepted risk estimates. We calculated MPI's benefit-to-risk ratios, defined by the annualized predicted MACE-to-LAR ratio and the predicted 6-mo-revascularization-to-LAR ratio. RESULTS: During follow-up, there were 22 MACE and 29 6-mo revascularizations. The administered radioactivity and effective radiation doses absorbed were similar between the study groups. Patients with inappropriate MPI had significantly higher LAR (median, 0.08% vs. 0.06%, P < 0.001), lower predicted MACE-to-LAR ratio (median, 1.5 vs. 4.3, P < 0.001), and lower predicted 6-mo-revascularization-to-LAR ratio (median, 5.4 vs. 15.5, P < 0.001). Women had higher LAR (median, 0.08% vs. 0.07%, P < 0.001) and lower predicted MACE-to-LAR ratio (median, 1.9 vs. 3.3, P < 0.001) and 6-mo-revascularization-to-LAR ratio (median, 4.4 vs. 17.5, P < 0.001). However, appropriate/uncertain use negated the difference between men and women in LAR (P = 0.94) and the predicted MACE-to-LAR ratio (P = 0.97). CONCLUSION: Inappropriate MPI use is associated with excess cancer risk and lower MPI's benefit-to-risk ratio. Appropriate/uncertain use neutralizes the sex gap in LAR with MPI.