Severity of Myocardial Nuclear Perfusion Imaging Defects is Associated with Late Gadolinium Uptake on Cardiac Magnetic Resonance Imaging

1624 Introduction: Myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT) is a widely used diagnostic tool in the evaluation for obstructive coronary artery disease (CAD). Patients with CAD or myocardial infarction may harbor varying degrees of myocardial scar, so called “fixed” defects, which portends increased mortality risk. Despite this, there are a paucity of studies that have investigated the correlation between SPECT assessment of fixed (scar) defects with scar identification on cardiac magnetic resonance imaging (MRI). We hypothesize that increasing SPECT perfusion segment defects correlates with greater scar burden by cardiac MRI. Methods: We performed a retrospective study (2010‑2019) in patients referred for both cardiac MPI and MRI, and were within 180 days apart. MPI fixed defect grading followed standardized guidelines: 1=mild, 2=moderate, 3= severe, 4=absent. MRI late gadolinium enhancement (LGE) was categorized in accordance with universally established protocols and served as the reference. We excluded patients with any cardiovascular events between MPI and cMRI, and patients with nonischemic cardiomyopathy. We used Spearman’s Rank Correlation and Fisher’s z‑transformation to obtain correlations Coefficients. Results: A total 185 patients and 3,145 segments (185 patients x 17 myocardial segments) were analyzed. The patient mean age of the studied population was 65 ± 11 and majority were males (71%). The most severe (grade 4 MPI) defects demonstrated a specificity 91% to predict >50% scar tissue thickness on MRI (likelihood ratio: 6.3). In addition, on a per segment basis, SPECT myocardial segments relating to left anterior descending (LAD) and left circumflex (LCx) territories demonstrated a moderate and significant correlation with MRI LGE scar as compared to the right coronary artery (RCA) myocardial segments (Figure 1). This relationship was strongest in males over age 65 with known CAD (p Conclusions: Increasing severity of SPECT perfusion defects correlates with increased scar on MRI. This relationship is strongest for the most severe perfusion defects, LAD/LCx distribution (compared to RCA territory), male gender, and age over 65 with CAD. These findings underscore the clinical relevance of SPECT assessed fixed defects. The use of prone imaging to resolve inferior wall SPECT perfusion defects may improve the accuracy and interpretation of myocardial segments along the RCA territory, and the correlation with MRI detected scar. These findings warrant further investigation in large prospective studies.