Age-Dependent Risk of Long-Term All-Cause Mortality in Patients Post-Myocardial Infarction and Acute Kidney Injury.

Objectives: We aimed to investigate the association between acute kidney injury (AKI) and the risk for long-term (up to 10 years) all-cause mortality among elderly compared with younger patients following an acute myocardial infarction (AMI).

Methods: This study was a retrospective analysis of the Soroka Acute Myocardial Infarction registry and covered the years 2002 to 2017. It included patients diagnosed with an AMI who had a baseline estimated glomerular filtration rate (eGFR) greater than 60 mL/min/1.73 m² and serum creatinine measurements available during hospitalization. The patients were stratified by age: elderly (aged 65 years or older at admission) and younger. In each stratum, two groups were defined based on the presence of an AKI. The survival approach (Kaplan-Meier survival curves, log-rank test and Cox regressions) was utilized to estimate and compare the probability of long-term (up to 10 years) all-cause mortality in each group.

Results: Among the 10,511 eligible patients, which consisted of 6132 younger patients (58.3%) and 4379 elderly (41.7%), an AKI occurred in 15.2% of cases, where the elderly patients experienced a higher incidence than the younger patients (20.9% vs. 11.2%, p < 0.001). The presence of an AKI significantly increased the risk of death in both age groups, with the association being stronger among the younger patients (AdjHR = 1.634, 95% CI: 1.363-1.959, p < 0.001) than among the elderly (AdjHR = 1.278, 95% CI: 1.154-1.415, p < 0.001, p-for-interaction = 0.020).

Conclusions: An AKI following an AMI was associated with a high risk for long-term all-cause mortality in both age groups, with a stronger association among younger patients.