Abstract 21379: The Prognostic Value of Longitudinal Change in Myocardial Perfusion Defect Size as Measured by Rubidium-82 Positron Emission Tomography
Tracking coronary artery disease (CAD) via myocardial perfusion imaging (MPI) may have value in guiding therapeutic management for minimizing coronary event risk. Few studies have evaluated the effects of changes in myocardial perfusion as measured by positron emission tomography (PET MPI) on clinical outcomes. Accordingly, this study identified 552 patients who underwent serial rubidium-82 PET MPI for evaluation of suspected or known CAD. The extent of left ventricular (LV) stress perfusion defects was measured at both scans Objectivesly by automated software as the percentage of the LV mass with <60% relative perfusion. All patients received aggressive medical therapy and 12% underwent interim revascularization. Mortality information was obtained through the National Death Index with mean follow-up of 2.5 years. Cox models were developed to estimate the effects of changes in stress perfusion defect size (change between serial scans in % of LV with stress perfusion defects) on all-cause and cardiac mortality risk. At the initial PET scan, 173 (31%) patients had no stress perfusion defects, 215 (39%) had small stress perfusion defects involving <5% of the LV, and 164 (30%) had large stress perfusion defects involving 5% or more of the LV. Interim revascularization rates among those with no, small, and large stress perfusion defects were 2%, 8%, and 26%, respectively. The average number of days between PET scans was 682. Revascularization was associated with an average improvement in perfusion defect size of 4% of LV mass after controlling for baseline defect size. For each 5% improvement in defect size between scans, there was a 20% improvement in risk of both all-cause (HR=0.8; p<0.01) and cardiac-specific mortality (HR=0.8; p=0.04). Patients with perfusion defect worsening of 5% or more (11% of the cohort) were at particularly high mortality risk (HR=2.7; p=0.01). These Results were unchanged when restricted to those with large stress perfusion defects or to those treated with medical therapy only. Improvements in myocardial perfusion as measured by PET MPI in response to either revascularization or medical management were associated with reduced mortality risk. PET MPI is useful in tracking CAD and guiding therapeutic management for risk minimization.
- © 2010 by American Heart Association, Inc.