The determinants and prognostic value of albuminuria remain unclear in patients with adult congenital heart disease (ACHD), especially in those with Fontan circulation (FC).

We retrospectively reviewed 512 consecutive ACHD patients and investigated the determinants of urinary albumin-to-creatinine ratio (ACR) and albuminuria (MAU) and their association with all-cause mortality. Demographic data and laboratory and hemodynamic parameters were collected. Regression analysis and Cox proportional hazard models were used to identify the relationship between log ACR and variables, and clinical factors and all-cause mortality, respectively.

Body mass index, aortic systolic blood pressure (ASP), arterial oxygen saturation (SaO₂), glycated hemoglobin (HbA1c), B-type natriuretic peptide, and diuretic use were independently associated with log ACR. ASP, SaO₂, and HbA1c were independently associated with MAU (P < .05-0.001). The prevalence of MAU was highest in unrepaired patients with low SaO₂ (50%; P < .0001). Log ACR and MAU were associated with exercise capacity and all-cause mortality (P < .0001 for both) independent of renal function. Patients with ACHD, MAU, and renal dysfunction (n = 23) had the highest risk of all-cause mortality, while those without MAU or renal dysfunction had the lowest risk (P < .0001). These prognostic values remained significant in separate analyses of Fontan and biventricular circulation (P < .0001).

ASP, SaO₂, and HbA1c levels were independently associated with MAU in ACHD patients. MAU and log ACR were associated with all-cause mortality in patients with Fontan and biventricular circulation, independent of renal dysfunction.