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Introduction Patients with ESRD are at an increased risk of accelerated atherosclerosis, calcification, microvascular and endothelial dysfunction which increases vascular stiffness which leads to a higher risk of cardiac events in this high-risk population. 82-Rubidium Positron Emission Tomography (Rb PET) can be used to inform perioperative risk assessment of coronary artery disease (CAD) in patients being appraised for kidney transplantation. In addition to an assessment of regional ischemia from epicardial coronary stenosis, it also has the ability to detect microvascular disease, using myocardial blood flow (MBF), specifically myocardial blood flow reserve (MBFR). In this study, we investigated the relationship between global MBFR and traditional risk factors, perfusion defects on Rb PET, CAD on invasive coronary angiography(CAG), and CV outcomes.Methods Retrospective single-centre study, of ESRD patients who had a clinically indicated Rb PET to exclude CAD, as part of a pre-operative assessment for kidney transplantation, between Jan 2013 and Sep 2019 at Manchester University NHS Foundation Trust. A comprehensive review of clinic letters, in-patient admission, discharge documents was performed by a researcher blinded to the Rb PET result (A.V.). MBFR was calculated as the ratio of stress to rest MBF and patients were divided into two groups using a MBFR threshold of ≤1.8, based on a large prospective prognostic study. 1 Differences of MBFR between different groups were explored using Mann Whitney U or Kruskal Wallis tests for continuous variables.Results 75 patients were included in our study, aged between 33–81(median 62) years. MBFR was found to be universally reduced with </=1.8 in 92%. As seen in table1, risk factors such as diabetes and obesity were associated with a higher reduction in MBFR and MBF. In the 49/75 patients who had an invasive CAG after Rb PET study, MBF at rest was significantly reduced in patients with severe CAD(p<0.018). Follow up period after Rb PET was for a median duration of 2.5 years (3 months to-5 years) at the time of review. 27/75 patients died with 10 recorded as a cardiac cause. Although the cause of death was not known in 10/27 patients, those that died had a lower MBF at rest (P:0.046). The main limitation in our study was that MBFR was universally reduced and the small number of participants with CV outcomes, making it difficult to find a statistically significant association between MBFR with MPI and CAG findings and cardiac outcomes.Abstract 6-012 Table 1Shows the significant reduction MBFR in DM, MBF at stress and rest with obesity, MBF at rest with significant CAD on CAG and those that died N Median (IQR) P Value Diabetes Mellitus (DM)MBFR Yes 56 1.130 (0.980, 1.555) 0.0389 No 19 1.400 (1.265, 1.695) ObesityMBF at stress Yes 45 1.290 (1.020, 1.640) 0.012 No 27 1.620 (1.450, 1.735) ObesityMBF at rest Yes 45 1.010 (0.910, 1.200) <0.001 No 27 1.220 (1.121, 1.490) CAG findingsMBF at rest Significant disease 37 1.370 (1.010, 1.630) 0.018 Non-significant disease 9 1.320 (1.050, 1.560) DiedMBF at rest Yes 25 0.990 (0.860, 1.230) 0.046 No 47 1.150 (1.010, 1.425) Conclusion Reduced MBFR was a near-universal finding in keeping with current knowledge of the prevalence of epicardial and microvascular disease in this population. Like previous studies, we found risk factors such as diabetes and obesity to be associated with reduced MBFR and MBF. A better understanding of pathophysiology of reduced MBFR in this high-risk population could guide risk stratification and targeted therapy, with the aim of reducing cardiac events.Reference Patel KK, Spertus JA, Chan PS, et al. Myocardial blood flow reserve assessed by positron emission tomographymyocardial perfusion imaging identifies patients with a survival benefit fromearly revascularization. Eur Heart J 2020;41(6):759–768.doi:10.1093/eurheartj/ehz389.Abstract 6-012 Figure 1Distribution of MBFR within each group of outcomesAbstract 6-012 Figure 2Distribution of MBFR in patients with significant perfusion defects on myocardial perfusion imaging and in patients with significant CAD on CAG