Background: Microalbuminuria is one of the earliest biomarkers of kidney injury that reflects an endothelial dysfunction with increased glomerular permeability and it is independently associated with adverse outcomes in several clinical situations.
Methods: To evaluate the very long-term prognostic yield of baseline microalbuminuria in patients with acute coronary syndrome (ACS), we prospectively studied 589 ACS patients admitted to three Italian hospitals. The baseline albumin/creatinine ratio (ACR) was measured on days 1, 3, and 7 in 24-h urine samples. Patients were followed for 24 years or until death.
Results: Virtually all patients completed the follow-up, representing 7066 person-years. During follow-up, 482(82%) had died: 38% due to non-sudden cardiac death (non-SCD), 19% sudden cardiac death (SCD), and 43% due to non-cardiac (non-CD) death.
Throughout the 1st admission week, ACR was consistently higher in the patients who died during follow-up than in those who survived. Similar higher values were found for deaths from non-SCD causes.
The unadjusted Cox regression analysis revealed that ACR is a significant predictor of all-cause mortality (HR:1.24; 95%CI 1.20-1.28; p˂0.0001) and the 3 causes of death (HR:1.38; 95%CI 1.31-1.45; p˂0.0001), (HR:1.16; 95%CI 1.07-1.25; p=0.0001) and (HR:1.17; 95%CI 1.10-1.23; p˂0.0001) for non-SCD, SCD and non-CD respectively. Yet the fully adjusted model showed that ACR is a significant independent predictor of all-cause mortality (HR:1.10; 95%CI 1.08-1.14; p˂0.0001) and only non-SCD (HR:1.18; 95%CI 1.12-1.25; p˂0.0001).
A positive interaction between ACR and the presence of heart failure during admission (HR:1.12; 95%CI 1.02-1.24; p=0.02) and a negative interaction with LVEF (HR:0.86; 95%CI 0.78-0.95; p=0.004) for all-cause death was also observed at the multivariable level.
Conclusion: This prospective study shows that baseline ACR during ACS seems to be a strong independent long-term risk predictor, chiefly associated with non-sudden cardiac death. Positive independent interaction with indicators of heart failure has been also observed.