ImportanceLong-term use of anabolic androgenic steroids (AASs) is associated with a high risk of left ventricular hypertrophy, heart failure with reduced systolic function, and early sudden death, with the mechanism of progression being understudied. Early and persistent impaired myocardial microcirculation could be of clinical importance and a potential underlying mechanism of frequent and early cardiac disease among individuals with AAS use and a future potential target for intervention.ObjectiveTo investigate coronary microcirculation by measuring myocardial flow reserve (MFR) in men with current and former AAS use compared with controls with no prior AAS use, using cardiac rubidium 82 (82Rb) positron emission tomography/computed tomography (PET/CT).Design, Setting, and ParticipantsThis cross-sectional study included men involved in recreational strength training without established cardiovascular disease grouped according to their history of AAS use. The study was conducted November 24, 2021, to August 16, 2023.ExposureCardiac PET/CT with 82Rb was performed at rest and after adenosine-induced stress.Main Outcome and MeasureThe primary outcome of this study was the MFR among the study groups; a secondary outcome was the coronary calcium score. By definition, impaired myocardial microcirculation was determined using a cutoff of MFR less than 2, and subclinically impaired microcirculation was determined using a cutoff of MFR less than 2.5.ResultsA total of 90 men (32 with current AAS use, 31 with former AAS use, and 27 controls) were included. Mean (SD) age was 35.1 (8.7) years. Elapsed duration since AAS cessation was a geometric mean of 1.5 (95% CI, 0.9-2.5) years. Eighteen men (58.1%) with former use discontinued AAS use more than 1 year before enrollment. Impaired MFR was present in those with current (6 [18.8%]) and former (1 [3.2%]) use, whereas no impairment was observed among the controls (P = .02). Subclinically impaired MFR was higher among men with current (9 [28.1%]) and former (8 [25.8%]) AAS use than the controls (1 [3.7%]) (P = .02). In a multivariable logistic regression model among men with former AAS use, every doubling of the accumulated weekly duration of AAS use (log2) was independently associated with a factor 2 increase in the risk of impaired MFR less than 2.5 (odds ratio, 2.1; 95% CI, 1.03-4.35; P = .04).Conclusions and RelevanceIn this study, men with former AAS use displayed impaired MFR years after AAS cessation, suggesting impaired coronary microcirculation persists beyond active use.