Introduction: Transplant Renal Artery Stenosis (TRAS) stands as the leading vascular complication following kidney transplantation (KT), posing a significant threat to graft longevity and elevating mortality risk post-KT. Prompt diagnosis and timely intervention can prevent irreversible allograft damage caused by TRAS. A substantial body of research has identified several risk-factors for TRAS, such as prolonged cold ischemia-time, extended-criteria donors, and delayed graft function, primarily in the context of deceased donor-KT. However, a significant gap persists in comprehending specific risk factors for TRAS and its long-term outcomes in living donor-KT. This matched case-control study, conducted at a premier national transplant center that predominantly performs living donor-KT, assesses various risk factors and long-term outcomes of clinical-TRAS (cTRAS) in kidney transplant recipients(KTRs).
Methods: cTRAS cases diagnosed from January 2007 to December 2022 were individually matched with four control KTRs to control for various confounding factors. The study was powered to evaluate whether ex-vivo arterial vascular reconstruction of multiple renal arteries (VR-MRA) increases the risk of cTRAS by employing a dual-method analytical framework integrating multivariable regression analysis with all predictor variables and bidirectional stepwise selection to assess VR-MRA's impact on increased risk of cTRAS development.
Results: Of the 2,454 KT performed during the study period, 28 KTRs (1.14%) were diagnosed with cTRAS around 3.62 ± 1.04 months post-KT, with stenosis predominantly in the juxta-anastomotic region. The majority of cTRAS cases (92.86%) presented with renal allograft dysfunction, with 57.14% of them necessitated ≥2 antihypertensive medications. Mild acute tubular necrosis was the most common biopsy finding in 67.85% of cTRAS cases. Endovascular intervention as percutaneous transluminal angioplasty (PTA), accompanied by stenting, was performed in 89.28% of cases, while PTA alone was utilized in three cases. All cTRAS cases demonstrated favorable outcomes over 6-180 months of follow-up. Recurrence of cTRAS occurred in two cases, leading to a 7.14% reintervention rate. Both these cases were successfully treated with cutting balloon-angioplasty and drug-eluting stenting. A significant finding of this study is the identification of ex-vivo VR-MRA as an independent risk factor for cTRAS (P<0.001) (Figure-a, table-1). Notably, cTRAS cases and control KTRs demonstrated comparable long-term graft and patient survival rates (figure-b)
Conclusion: This largest single-center experience from Asia on clinical-TRAS underscores VR-MRA as a significant independent risk factor for cTRAS. We advocate for regular color Doppler screening during the initial six months post-KT, especially in KTRs with VR-MRA and unexplained renal allograft dysfunction, to ensure prompt detection and timely intervention.