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Background: Up to date there is no evidence of the association between      microalbuminuria, measured as single spot urine albumin to creatinine ratio (ACR), with very long-term mortality in patients with non-ST segment Elevation Acute Coronary Syndromes.

Aim: To evaluate the association between admission ACR and very long-term all-cause mortality in an unselected cohort of non-ST-segment elevation acute coronary syndromes patients.

Methods: A prospective cohort study was conducted, including patients with non-ST-segment elevation acute coronary syndromes admitted in the Intensive Care Unit. The ACR was determined in spontaneous urine samples during the first 24 hours after admission and analyzed by immunoturbidimetry. The primary endpoint was all-cause mortality during the follow-up. Actuarial survival curves were compared by log rank test and a logistical Cox regression analysis was performed to identify variables independently associated with mortality in the follow-up. Statistics were calculated using the IBM Statistics program SPSS version 26. 

Results: 600 patients were analyzed. The overall average ACR value was 7 mg/gr (95% CI 4-26). 76% had normoalbuminuria (ACR 0-30 mg/gr), 22% had microalbuminuria (ACR 30-300 mg/gr), and 1.5% had macroalbuminuria (ACR > 300 mg/gr). The median and interquartile range of follow-up was 12 years (95% IC 11-14). The average ACR among those who met the primary endpoint was 59.15 mg/gr (95% CI 52-66) and among the survivors, 27.66 mg/gr (95 % CI 63-77), p > 0,003. ACR terciles were defined by 33th and 66th percentiles: tercile 1: patients with ACR of 0 to 4 mg/gr, tercile 2: ACR from 4 to 17 mg/g and tercile 3 values greater than 17mg/gr. Strong associations were observed between ACR with age, hypertension, stroke and history of COPD, previous use of angiotensin II converter/blocking enzyme inhibitors, systolic blood pressure at admission, ST segment deviation, left ventricle ejection fraction and elevation of serum Troponin T and CPK MB.  All cause-mortality during the follow-up was 14% (CI 95% 11-17). Elevation of ACR was significantly associated with long term mortality risk: log rank test chi square: 133.936, p = 0.0001. By multivariate Cox regression analysis adjusted by age, gender, diabetes, hypertension, serum creatinine, troponin T elevation, ST segment deviation, previous AMI, prior use of aspirin, statins and percutaneous coronary intervention after hospitalization, the ACR was independently associated with a 12-year follow-up mortality: OR 13 (95% IC 5-35; p < 0.0001). 

Conclusion: Single spot urine ACR at admission is a strong predictor of 12-year follow-up mortality in an unselected cohort of patients with non-ST-segment elevation acute coronary syndromes.