Characterizing Resting Myocardial Blood Flow by Left Ventricular Geometry Using Positron Emission Tomography.

656 Introduction: Left ventricular hypertrophy (LVH) is a common compensatory mechanism for chronic increases in myocardial wall stress that often results in pathology characterized by impaired myocardial blood flow that is independent of epicardial coronary artery disease. Impairment in myocardial blood flow has been closely tied to cardiovascular outcomes, but to date resting myocardial blood flow (rMBF) differences have not been examined in the four established ventricular geometries; normal, remodeled, concentric, and eccentric. In this study we examine changes in resting myocardial blood flow stratified by gender and type of LVH. Methods: 1,488 individuals with echocardiograms and PET stress tests without significant perfusion abnormalities within 30 days of each other were included in this study. PET stress scans were performed under fasting conditions on an Attrius PET scanner (Positron, Westmont, IL) with Ge-68 rod source attenuation correction. Rest emission data were obtained over 7 min using generator-produced Rb-82 (Bracco Diagnostics, Monroe Township, NJ). MBF was collected using FDA-approved software (HeartSee™, University of Texas, Houston). 2D echocardiography parameters were collected using GE Vivid E95 (General Electric Vingmed, Horton, Norway) ultrasound machines equipped with a 4-7 MHz transducer. Rate pressure product corrected (RPP Cor) rMBF, were compared by gender and LV groups. Estimated averages were obtained after adjusting for significant covariates from a pool of 20 clinically judged as potentially relevant. Covariates included were those being significant (p<0.2) to remain in model under backward selection. All possible means comparisons were carried out and p-values adjusted by the Tukey’s test (alpha=0.05 for each analysis variable). Adjusted estimated means (at observed means of covariates) with corresponding standard errors are reported. Analyses were carried out in SAS 9.4. Results: In patients with normal LV geometry, women had significantly higher rate-pressure-product-corrected (RPP Cor) rMBF (cc/min/g) than men; 0.86 ± 0.03 vs. 0.75 ± 0.02 (p<0.001). Comparisons of RPP cor rMBF between LV geometries showed no significant intra-gender differences. (Figure 1) Conclusion: There were significant differences in rMBF across the various LV geometries between men and women. However, there were no significant differences in myocardial blood flow per gram of tissue between different LV geometries. These findings mirror studies from prior animal models and suggest that PET-measured flows are accurate in both normal and pathological human hearts.