Coronary Microvascular Dysfunction Predicts Long-Term Outcome in Simultaneous Pancreas-Kidney Transplantation

Background Patients with diabetes are at increased cardiovascular risk. Simultaneous pancreas-kidney transplantation (SPKT) is the treatment of choice in patients with type 1 diabetes mellitus and diabetic nephropathy. We assessed coronary flow reserve (CFR) by transthoracic echocardiography as a marker of major adverse cardiac events (MACE) in SPKT patients. Methods We studied 48 consecutive SPKT patients (28 male, age at SPKT 54 ± 8 years). Time from transplantation was 8.5 ± 3 years. Follow-up was 4.6 ± 1.8 years. Coronary flow velocity in the left anterior descending coronary artery was detected by Doppler echocardiography at rest and during adenosine infusion. CFR was the ratio of hyperemic diastolic flow velocity (DFV) to resting DFV. A CFR ≤ 2 was considered abnormal and a sign of coronary microvascular dysfunction. MACE were cardiac death, myocardial infarction, and heart failure. Results CFR was 2.55 ± 0.8. CFR was ≤2 in 13 (27%) patients. CFR was lower in SPKT patients with MACE (2.1 ± 0.7 vs 2.7 ± 0.8, P =.03) and patients with MACE had a higher incidence of CFR ≤ 2 (P =.03). Time from transplantation was shorter in patients with MACE (P < .0001). Patients with CFR ≤ 2 had a lower MACE-free survival (P = .03). CFR ≤ 2 predicted the risk of MACE (P = .007) independently from coronary artery disease and metabolic control. However, this predicted role is lost when adjusted for the time from transplantation, which plays a protective role (P = .001). Conclusions In SPKT, CFR ≤ 2 may be a reliable marker for MACE, independent of coronary artery disease diagnosis. However, this role seems to be reduced over time. This finding suggests a gradual reduction of cardiovascular risk in SPKT patients.