['Patients with unstable angina or myocardial infarction are at risk of acute kidney injury, which may be aggravated by the iodine-containing contrast agent used during coronary angiography; however, the relationship between these two conditions remains unclear.', 'The current study investigated the relationship between acute kidney injury and coronary heart disease prior to coronary angiography.', 'All patients were evaluated after undergoing coronary angiography in the cardiac catheterization laboratory of the Vinzentius Hospital in Landau, Germany, in 2011. The study group included patients with both acute coronary heart disease and acute kidney injury (as defined according to the classification of the Acute Kidney Injury Group); the control group included patients without acute coronary heart disease. Serum creatinine profiles were evaluated in all patients, as were a variety of demographic and health characteristics.', 'Of the 303 patients examined, 201 (66.34%) had coronary artery disease. Of these, 38 (18.91%) also had both acute kidney injury and acute coronary heart disease prior to and after coronary angiography, and of which in turn 34 (16.91%) had both acute kidney injury and acute coronary heart disease only prior to the coronary angiography. However, the occurrence of acute kidney injury was not significantly related to the presence of coronary heart disease (P = 0.95, Chi-square test).'] Is coronary heart disease significantly linked to acute kidney injury identified using Acute Kidney Injury Group criteria?