Left Ventricular Ejection Fraction Reserve and Its Association with Myocardial Perfusion, Coronary Calcification, and Strain in Type 2 Diabetes Without Overt Cardiovascular Disease

Background : Type 2 diabetes (T2D) is a major risk factor for cardiovascular disease (CVD), but the relationships between myocardial function, microvascular function, and atherosclerotic burden remain underexplored in asymptomatic individuals. This study investigates the associations between left ventricular ejection fraction (LVEF)-reserve, myocardial flow reserve (MFR), perfusion defects, coronary artery calcium score (CACS), and global longitudinal strain (GLS) in individuals with T2D but without overt CVD. Methods : Cross-sectional analysis of 871 individuals with T2D without overt CVD, recruited between 2020-2023. All underwent cardiac 82-Rubidium PET/CT to assess LVEF-reserve, MFR, perfusion defects, and CACS. GLS was measured using echocardiography. Associations were examined using linear regression adjusted for cardiovascular risk factors. Results : Mean (SD) age was 64.9 (±9.0) years, diabetes duration was 13.9 (±8.4) years, and 262 (30%) were women. Higher MFR was associated with higher LVEF-reserve (β = 1.64, 95% CI: 1.18 to 2.11, p<0.001). Individuals with CACS > 300 had lower LVEF-reserve than those with CACS ≤ 300 (β = -1.31, 95% CI: -2.01 to -0.60, p<0.001). Presence of Perfusion defects were associated with lower LVEF-reserve (β = -1.58, 95% CI: -2.32 to -0.85, p<0.001). LVEF-reserve was not associated with GLS (p=0.28). Sensitivity analysis excluding 248 participants with perfusion defects confirmed the association between MFR and LVEF-reserve (β = 1.52 (95% CI: 1.01, 2.04), p<0.001). Conclusions: In individuals with T2D without overt CVD, lower MFR, presence of perfusion defects, and CACS >300 were associated with lower LVEF-reserve. Underscoring a potential role of microvascular dysfunction in subclinical systolic impairment.