Impact of renal dysfunction and acute kidney injury on outcome in elderly patients with acute coronary syndrome undergoing percutaneous coronary intervention.

Background: Chronic kidney disease is common in patients admitted with acute coronary syndrome and its prevalence dramatically increases with age. Understanding the determinants of adverse outcomes in this extremely high-risk population may be useful for the development of specific treatment strategies and planning of secondary prevention modalities.

Aim: The aim of this study was to assess the impact of baseline renal function and acute kidney injury on one-year outcome of elderly patients with acute coronary syndrome treated with percutaneous coronary intervention.

Methods: Patients aged 75 years and older with acute coronary syndrome undergoing successful percutaneous coronary intervention were selected among those enrolled in three Italian multicentre studies. Based on the baseline estimated glomerular filtration rate (eGFR) calculated using the Cockcroft-Gault formula ([(140-age) × body weight × 0.85 if female]/(72 × serum creatinine)* 1.73 m of body surface area), patients were classified as having none or mild (eGFR ≥60 ml/min/1.73 m), moderate (eGFR 30-59 ml/min/1.73 m) or severe (eGFR <30 ml/min/1.73 m) renal dysfunction. Acute kidney injury was defined according to the Acute Kidney Injury Network classification. All-cause and cardiovascular mortality, non-fatal myocardial infarction, rehospitalisation for cardiovascular causes, stroke and type 2, 3 and 5 Bleeding Academic Research Consortium bleedings were analysed up to 12 months.

Results: A total of 1904 patients were included. Of these, 57% had moderate and 11% severe renal dysfunction. At 12 months, patients with renal dysfunction had higher rates ( < 0.001) of all-cause (4.5%, 7.5% and 17.8% in patients with none or mild, moderate and severe renal dysfunction, respectively) and cardiovascular mortality (2.8%, 5.2% and 10.2%, respectively). After multivariable adjustment, severe renal dysfunction was associated with a higher risk of all-cause (hazard ratio (HR) 2.86, 95% confidence interval (CI) 1.52-5.37,  = 0.001) and cardiovascular death (HR 3.11, 95% CI 1.41-6.83,  = 0.005), whereas non-fatal events were unaffected. Acute kidney injury incidence was significantly higher in ST-elevation myocardial infarction versus non-ST-elevation acute coronary syndrome patients (11.7% vs. 7.8%,  = 0.036) and in those with reduced baseline renal function ( < 0.001), and it was associated with increased mortality independently from baseline renal function and clinical presentation.

Conclusions: Baseline renal dysfunction is highly prevalent and is associated with higher mortality in elderly acute coronary syndrome patients undergoing percutaneous coronary intervention. Acute kidney injury occurs more frequently among ST-elevation myocardial infarction patients and those with pre-existing renal dysfunction and is independently associated with one-year mortality.