Between Oct @ , @ , and July @ , @ , @ patients aged @ years or older undergoing cardiac catheterisation with an estimated glomerular filtration rate of @ mL/min per @ m ( @ ) or less and one or more of several risk factors ( diabetes mellitus , history of congestive heart failure , hypertension , or age older than @ years ) were randomly allocated in a @:@ ratio to left ventricular end-diastolic pressure-guided volume expansion ( n = @ ) or the control group ( n = @ ) who received a standard fluid administration protocol .