Acute kidney injury, baseline renal function, troponin, and survival after myocardial infarction

Background: The roles of chronic kidney disease and acute kidney injury (AKI) as determinants of short- and long-term survival following myocardial infarction (MI) have not been well investigated. Methods: A retrospective analysis of electronic health record data was conducted for U.S. veterans between 2002 and 2015, with up to 15 years of follow-up after MI. Eligible participants included 49,150 veterans with a serum creatinine measurement prior to MI hospitalization. AKI stage was determined by the change between the pre-hospitalization creatinine level and the peak in-hospital measurement. The associations of AKI, estimated glomerular filtration rate (eGFR), and troponin I ratios with survival were evaluated using Cox proportional hazards models. Results: Compared to the no-AKI group, the hazard ratios (HRs) and 95% confidence intervals (CIs) for 30-day mortality were 3.12 (2.87-3.39), 5.12 (4.65-5.65), and 7.81 (6.93-8.81) across worsening stages of AKI. For 15-year mortality, the HRs were 1.76 (1.68-1.85), 2.33 (2.17-2.50), and 2.66 (2.37-2.99). Compared to those with eGFR >60 mL/min/1.73 m², HRs (95% CI) for 30-day mortality were 1.23 (1.13-1.33), 1.46 (1.33-1.59), and 1.92 (1.72-2.13) across decreasing eGFR levels. For 15-year mortality, HRs were 1.21 (1.17-1.25), 1.55 (1.49-1.61), and 2.13 (2.03-2.24). Mortality rates increased with rising troponin I (cTnI) ratios, particularly for 30-day mortality. Conclusions: AKI, baseline eGFR, and troponin levels were associated with both short- and long-term survival following MI. AKI during MI hospitalization was a particularly strong determinant of short-term mortality.