The Role of Albuminuria in Diagnosing and Stratifying Kidney Disease in Heart Transplant Recipients: A KDIGO Criteria-Based Analysis

Abstract

Background: Chronic kidney disease (CKD) is a common but poorly characterized complication in heart transplant (HT) recipients due to limited use of renal damage markers, such as albuminuria. Our aim is to determine CKD prevalence based on the Kidney Disease Improving Global Outcomes (KDIGO) criteria, assess CKD risk stratification according KDIGO guidelines, and describe the use of cardiorenal protective drugs in a contemporary HT cohort. Methods: A cross-sectional, single-center study was conducted in stable HT recipients under follow-up in 2023. CKD was defined as an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73m2 (using CKD-EPI) and/or albumin-to-creatinine ratio (UACR) ≥ 30 mg/g. Patients were stratified into KDIGO risk categories based on eGFR and UACR thresholds. Results: Among 207 patients (median age 65 years; 29% women; median time since transplant: 8 years), the median eGFR was 51 mL/min/1.73m2, with 58.9% having an eGFR < 60 mL/min/1.73m2 and median UACR was 45 (8–173) mg/g, with 57% showing elevated UACR. The prevalence of CKD was 79.2%, with 36 (17.4%) patients exhibiting elevated UACR despite an eGFR ≥ 60 mL/min/1.73m2. A total of 23.7%, 19.8%, 21.7%, and 34.8% were classified as low, moderate, high, and very high KDIGO risk categories, respectively. Among patients meeting the CKD criteria, 37.2% were on ACEi/ARBs and 26.2% on SGLT2i. Conclusions: CKD is highly prevalent in HT recipients, with UACR improving diagnostic accuracy. Over half of patients fell into high-risk KDIGO categories, indicating substantial CKD severity. However, the underuse of renal-protective therapies highlights the need for better alignment with current clinical guidelines.