Abstract 14782: Quantitative Myocardial Perfusion Results From the EXErcise to Regadenoson in Recovery Trial (EXERRT)
Introduction: Current stress myocardial perfusion imaging (MPI) protocols require a pre-test decision whether a patient (pt) will undergo either exercise or pharmacologic stress. The EXERRT trial evaluated use of regadenoson during recovery in pts who did not achieve ≥85% maximum predicted heart rate or ≥5 METs with exercise.
Methods: In this multicenter, 1,147 pt clinical trial, following rest SPECT perfusion, eligible pts were randomized to receive 0.4 mg IV regadenoson at min 3 of a 5 min slow walk recovery (Group 1, n=578) or regadenoson administered 1 hour later (Group 2, n=569). This rest and stress pair was termed MPI1. All pts underwent non-exercise regadenoson SPECT perfusion 1-14 days later. This was paired with the initial rest SPECT and characterized as MPI2. Images were interpreted by 3 blinded core lab readers and underwent quantitative analysis (Emory Cardiac Toolbox, V3.2).
Results: Past MI was present in 23% and known CAD in 56%. MPI1 was a 1 day study in 96% of pts with rest and stress MPI performed on the same day. Using the median assessment of the number of segments with a reversible perfusion defect to define non-ischemic (0-1 segment) vs ischemic (≥2 segments), the overall reader agreement rate for Groups 1 and 2 was 75% and 77%, respectively; using quant this was 81% and 75% (Fig 1A). Pts were categorized as ischemic approx twice as often by quant than by readers (Fig 1B). Approx 30-50% more pts were categorized as ischemic on MPI2 than on MPI1, whether interpreted by readers or by quant.
Conclusion: Agreement rates between Groups 1 and 2 were similar whether evaluated by readers or quant. However, quant resulted in more pts categorized as ischemic than by readers. Also, more pts were categorized as ischemic on MPI2 than MPI1 by readers or quant. “Shine through” of residual perfusion from the rest study into the stress perfusion scan is the most likely explanation. One-day MPI protocols using 3:1 ratio of radiotracer may detect ischemia less well than widely believed.
Author Disclosures: G.S. Thomas: Speakers Bureau; Significant; Astellas Pharma. S.J. Cullom: Other; Significant; EXERRT Scientific Advisor. T.M. Kitt: Employment; Significant; Astellas. K.M. Feaheny: Employment; Significant; Astellas. K. Ananthasubramaniam: Research Grant; Significant; Astellas. R.J. Gropler: None. D. Jain: Research Grant; Significant; Astellas. Speakers Bureau; Significant; Astellas. Consultant/Advisory Board; Significant; Astellas. R.C. Thompson: None.
- © 2016 by American Heart Association, Inc.