Abstract 18221: Validation of Transient Ischemic Dilation Ratio Associated with Triple Vessel Disease in Gated SPECT Myocardial Perfusion Imaging (MPI) Using Regadenoson

Abstract

Background: In a recent retrospective study of 213 patients who underwent regadenoson MPI, the TID associated with severe disease was found to be 1.39 using non-obstructive disease on angiography to establish low risk for CAD. Framingham risk score less than 5% resulted in a higher cutoff of 1.43.The objective of this study was to validate the TID cutoffs associated with severe CAD for gated SPECT MPI rest/stress studies.

Methods: This is a retrospective study of patients who underwent dual isotope (thallium/technetium) MPI with Regadenoson between April 2009 and June 2011. The receiver operating characteristics were analyzed for 406 patients who had MPI and angiography. The validation cohort included 194 patients with an angiogram and MPI within 3 months from March 2010 to June 2011. Sensitivity analysis was performed. TID was calculated using Emory Cardiac Toolbox.

Results: In the validation cohort, the cutoff of 1.39 yielded a sensitivity (Se)/ specificity (Sp)/positive predictive value/negative predictive value of 10%, 91%, 17% and 85% for detecting triple vessel disease (3VD). Alternatively, a cutoff of 1.43 revealed a Se/Sp/PPV/NPV of 10%/95%/ 23%/86%.The ROC for TID as a predictor of 3VD in the overall population had an area under the curve (AUC) of 0.60. A cutoff of 1.39 yields Se/Sp/ positive likelihood ratio (LR+)/negative likelihood ratio (LR-) of 18.5%/94%/ 3.09/0.86, while 1.43 yields Se/Sp/LR+/LR- of 12%/95%/2.6/0.91.The overall population was stratified based on the MPI results. In the MPI positive group with n=315, AUC was 0.62 (figure 1). Using 1.39 as a cutoff yields Se/Sp/LR+/LR- of 18%/93%/2.87/0.87, while 1.43 results in Se/Sp/LR+/LR- of 12%/94%/2.1/0.93.

Conclusion:In MPI using Regadenoson, TID is a specific but not sensitive measure that is associated with 3VD in patients with an abnormal MPI. The two cut points yields similar results.