STUDY OBJECTIVEThis study seeks to examine whether the finding of an abnormal estimated glomerular filtration rate (eGFR) in the emergency department (ED) was associated with acute coronary syndrome in the population of patients presenting for investigation of chest pain.METHODSWe used prospectively collected data on adult patients presenting with suspected acute coronary syndrome to 2 EDs in Australia and New Zealand. Trained research nurses collected clinical data with a customized case report form. Creatinine measurements were taken on presentation, and the glomerular filtration rate ([GFR]; milliliters per minute per 1.73 m(2)) was estimated with the chronic kidney disease epidemiologic collaboration equation. The primary endpoint was acute coronary syndrome within 30 days of presentation, as adjudicated by cardiologists using standardized guidelines. Logistic regression analyses examined the relationship between eGFR and acute coronary syndrome.RESULTSAcute coronary syndrome was diagnosed in 421 (21%) of the 1,968 patients recruited. Compared with patients with an eGFR greater than 90 mL/minute per 1.73 m(2), patients with an eGFR between 60 and 90 mL/minute per 1.73 m(2) and patients with an eGFR less than 60 mL/minute per 1.73 m(2) were 1.64 (95% confidence interval 1.10 to 2.44) and 1.70 (95% confidence interval 1.01 to 2.77) times more likely to receive a diagnosis of acute coronary syndrome after controlling for age, sex, hypertension, dyslipidemia, family history of cardiac disease, diabetes, patient history of cardiac disease, cardiac troponin level, and ECG findings.CONCLUSIONThere is an independent association between eGFR and acute coronary syndrome risk in patients presenting to the ED with chest pain; this association is independent of age, traditional cardiac risk factors, medical history, troponin level, and ECG findings. Reduced eGFR should be considered an acute coronary syndrome risk factor, and clinicians should maintain high clinical suspicion for acute coronary syndrome in patients with abnormal renal function results regardless of whether they have known kidney disease, traditional acute coronary syndrome risk factors, or abnormal diagnostic test results. Risk stratification tools should include reduced eGFR as a high-risk feature.