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

Abstract

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.

Keywords: SPECT; appropriate use criteria (AUC); cancer; lifetime attributable risk (LAR); myocardial perfusion imaging (MPI); outcome.