Myocardial flow reserve in chronic kidney disease and renal transplantation: A cross-sectional study of ammonia PET

Objective Renal transplantation (RT)’s effects on coronary artery and microvascular diseases is not yet elucidated. We aimed to quantify myocardial blood flow (MBF) using ¹³ N-ammonia positron emission tomography (NH ₃ -PET) and compare the results between RT recipients and patients with chronic kidney disease (CKD). Methods Adenosine-stress NH ₃ -PET measurements of 29 RT recipients and 564 patients with CKD were assessed. Stress and rest MBF were calculated from the dynamic data of the initial 2 min after the ammonia injection. Myocardial flow reserve (MFR) was defined as stress MBF divided by rest MBF; MFR < 2.0 or stress MBF < 2.0 ml/g/min was considered a significant decrease. Results Stress MBF for RT recipients and patients with end-stage and mild-stage CKD was 2.03 ± 0.60, 1.72 ± 0.62, and 2.07 ± 0.61 ml/g/min, respectively; their MFRs were 2.00 ± 0.60, 1.68 ± 0.51, and 2.26 ± 0.69, respectively. Stress MBF and MFR were significantly greater in RT recipients than in patients with end-stage CKD ( P < 0.01 ). The MFR was significantly greater in patients with mild-stage CKD than in RT recipients ( p < 0.05 ); however, there was no significant difference in stress MBF. The proportion of patients with MFR ≥ 2.0 or stress MBF ≥ 2.0 ml/g/min was significantly higher in RT recipients than in patients with end-stage CKD (51.7% vs. 26.3%, and 58.6% vs. 26.3%, p < 0.01 ). Conclusion RT may improve MFR in patients with end-stage CKD by acting on adenosine vasodilation.