Letter: Outcomes of Kidney Transplant Recipients Undergoing Percutaneous Coronary Intervention

Dear Editor,

We found the article by Ang et al ¹ titled “Trends, Characteristics, and Outcomes of Percutaneous Coronary Intervention Among Kidney Transplant Recipients” to be of considerable interest. Ang et al ¹ compared in-hospital outcomes, temporal trends, and predictors of mortality between kidney transplant recipients (KTRs) and non-transplant patients undergoing percutaneous coronary intervention (PCI). KTRs were more likely to develop acute kidney injury (AKI) both before and after propensity-score matching. In contrast, the initially higher rates of bleeding complications (7.59% vs 4.96%) and transfusion (5.24% vs 2.75%) in KTRs were no longer significant after matching. They underscore the need for meticulous periprocedural management, kidney-sparing contrast strategies, and targeted risk stratification to mitigate renal complications in this growing, high-risk, population.

Zheng et al ² reported that renal transplant was associated with similar short-term outcomes to chronic kidney disease (CKD), and better outcomes than dialysis post PCI. After multivariable adjustment, kidney transplant was associated with an increased hazard for long-term mortality compared with CKD and dialysis. Another study ³ showed that AKI is an important prognostic determinant in KTRs undergoing coronary angiography and PCI. Periprocedural bleeding events were associated with AKI. Other authors reported that patients with coronary artery stenting before kidney transplant have similar long-term outcomes compared with patients managed medically. ⁴ Furthermore, Nakao et al ⁵ found that renal transplant may improve clinical outcomes after PCI, and it is encouraged for hemodialysis patients to increase life expectancy and reduce the occurrence of adverse events after PCI.

Several mechanisms might clarify why KTRs have a higher risk of AKI but similar in-hospital mortality rates. First, calcineurin inhibitors impair renal reserve and cause direct nephrotoxicity, both of which heighten vulnerability to contrast-induced kidney injury. ⁶ These agents upregulate endothelin-1 and drive superoxide-mediated nitric oxide scavenging, leading to persistent afferent-arteriolar constriction and reduced perfusion. ⁷ Secondly, long-term exposure will further activate the transforming growth factor-β/small mothers against decapentaplegic (TGF-β/Smad) signaling pathway and the oxidative stress pathway, thereby causing lumen damage, interstitial fibrosis, and progressive functional impairment of the transplanted organ. ⁸ Thirdly, immunosuppressants can also cause dyslipidemia, hypertension and endothelial dysfunction. ⁹ These conditions may lead to diffuse, calcified coronary artery disease, which may necessitate the use of a greater contrast dose and more complex treatment interventions.^10,11

In summary, KTRs undergoing PCI experience higher AKI risk and resource utilization despite similar in-hospital mortality compared with non-transplant patients. These findings highlight the need for tailored risk stratification, contrast-sparing strategies, and meticulous periprocedural management to optimize outcomes in this growing, high-risk, population.