Abstract 11488: Comparative Effectiveness of PET and SPECT Myocardial Perfusion Imaging for Identification of Low-Risk Patients With Cardiometabolic Disease

Introduction: The epidemiology of coronary artery disease (CAD) has shifted, with increasing cardiometabolic (CM) disease and decreasing obstructive CAD in patients referred for myocardial perfusion imaging (MPI). Coronary microvascular dysfunction, defined as impaired coronary flow reserve (CFR) by positron emission tomography (PET), has emerged as a key mediator of risk. Our objective was to assess whether CFR provides additive value to identify low-risk CM disease patients compared with single-photon emission computed tomography (SPECT) MPI. Methods: We retrospectively studied patients with CM disease (obesity, diabetes, or chronic kidney disease (CKD) stage ≥3) and without known CAD referred for PET or SPECT MPI at our center from 2006 to 2020. Annualized all-cause and cardiac mortality was determined from death certificates, and propensity-matched low-risk PET and SPECT patients were compared using Poisson and Cox regression. Results: CM disease was prevalent in consecutive MPI referrals without CAD including obesity (N=8869), diabetes (N=4896) and CKD (N=3555), and higher among PET MPI (p <0.001). Prevalence of summed stress score (SSS) >3 reflecting obstructive CAD was low (12%, 15% and 16%). Conversely, prevalence of CFR <2 was high (52%, 61% and 69%), reflecting impaired myocardial perfusion. In adjusted hazard analysis, normal MPI was associated with lower risk of all-cause and cardiac death (p <0.001). Normal PET (SSS ≤3 and CFR >2) was associated with lower all-cause death compared to normal SPECT (Figure, A). Normal PET and SPECT identified low-risk (<1%/year cardiac death) patients with obesity and diabetes, however those with CKD remained moderate-risk (1-3%/year) (Figure, B). Conclusion: CM disease is common among patients without CAD referred for MPI. Normal PET and SPECT MPI identify a low-risk group for obesity and diabetes, but not CKD. PET with CFR has additive prognostic utility to identify low-risk individuals compared to SPECT.