Abstract 21400: The Prognostic Value of Mild Perfusion Defects as Identified by Rubidium-82 Positron Emission Tomography Myocardial Perfusion Imaging
Positron emission tomography myocardial perfusion imaging (PET MPI) has enhanced sensitivity for identifying mild myocardial perfusion defects compared to other MPI modalities. Whether mild perfusion defects as measured by PET MPI provide prognostic information is not known. Among 3739 patients referred for rest-stress rubidium-82 PET MPI for evaluation of known or suspected coronary artery disease (CAD) between April 2000 and June 2006, we identified 2922 without significant severe stress perfusion defects, defined as relative perfusion <60% of maximum. Among this subset, automated software measured the extent of mild perfusion defects, defined as the percentage of the left ventricle (LV) with relative perfusion between 60% and 80% of maximum. The percentage of the LV mass with mild perfusion defects was grouped into <40%, 40–50%, 50–60%, 60–70%, & >70% of the LV. Mortality information was obtained through the National Death Index with mean follow-up of 3.2 years. Cox proportional hazards models were developed to estimate the independent prognostic value of mild perfusion defects after adjusting for important predictors of mortality. Greater extent of mild perfusion defects was associated with younger age, male gender, higher body mass index, and history of known CAD. Annual cardiac mortality rates across the aforementioned mild perfusion defect groups were 0.4%, 0.4%, 0.7%, 1.0%, and 0.6%, respectively (p for trend = 0.05). After adjustment for important predictors of mortality, greater extent of mild perfusion defects was associated with increased risk of cardiac mortality with hazard ratios across groups of 1.0, 0.9, 1.5, 2.2, and 2.2, respectively (p for trend = 0.04). A significant positive association was also observed for all-cause mortality (p for trend = 0.03). The extent of mild perfusion defects as measured via PET MPI provided independent prognostic information among individuals without significant severe stress perfusion defects - a group typically considered at low risk of cardiac events. Future research should determine whether relative perfusion measures characterizing mild perfusion defects provide value in guiding therapy.
- © 2010 by American Heart Association, Inc.