Coronary atherosclerotic burden vs. coronary vascular function in diabetic and nondiabetic patients with normal myocardial perfusion: a propensity score analysis

PURPOSE: To assess the relationship between coronary atherosclerotic burden and vascular function in diabetic and nondiabetic patients after balancing for coronary risk factors. METHODS: We studied 672 patients without overt coronary artery disease and normal myocardial perfusion on stress 82Rb PET/CT imaging. To account for differences in baseline characteristics between diabetic patients and nondiabetic patients, we created a propensity score-matched cohort considering clinical variables and coronary risk factors. RESULTS: Before matching, diabetic patients had higher coronary artery calcium (CAC) scores (p < 0.001) and lower coronary flow reserve (CFR; p < 0.001) than nondiabetic patients. After matching, CAC scores were comparable between diabetic and nondiabetic patients, but diabetic patients still had lower hyperaemic myocardial blood flow (p < 0.001) and CFR (p < 0.05). Patients were categorized by ln(CAC score) quartiles. There was a decrease in CFR with increasing CAC score quartile in both diabetic patients (p for trend < 0.01) and nondiabetic patients (p for trend < 0.005). Diabetes was associated with lower CFR across quartile categories (p < 0.002). In a multivariable linear regression analysis, CAC score was inversely related to CFR in both diabetic patients (p < 0.05) and nondiabetic patients (p < 0.001). CONCLUSION: Diabetic patients had higher CAC scores than nondiabetic patients, but the difference disappeared when clinical characteristics were taken into account. Of note, diabetic patients also had lower CFR regardless of CAC score than nondiabetic patients after matching. Thus, coronary atherosclerotic burden and vascular function have to be seen as two different entities.