Safety of gadodiamide mixed with a small quantity of iohexol in patients with impaired renal function undergoing coronary angiography

Gadolinium-based contrast agents can be used in diagnostic and interventional angiography, and are safe in recommended doses in patients with impaired renal function, but the image quality is usually unsatisfactory. The objective of the present study is to evaluate the safety of gadolinium mixed with a small quantity of iodine-based contrast agent and the image quality of this mixture in patients with renal insufficiency undergoing diagnostic coronary angiography. Forty-two patients with baseline creatinine level>1.5 mg/dl were randomized into gadolinium or iodine groups. In the gadolinium group gadodiamide was mixed with 1:3 iohexole and in the iodine group only this agent was used as contrast material. Peak creatinine levels 48-72 h after the procedure were measured. The primary end point was the development of contrast-induced nephropathy (CIN), defined as >25% increase of baseline creatinine levels, and the secondary end points were absolute and relative changes in baseline creatinine levels. Total contrast volumes used were not different between groups (57+/-11 ml in gadolinium and 55+/-10 ml in iodine; P=0.68). Mean creatinine level did not increase significantly in the gadolinium group (from 1.9+/-0.3 to 1.9+/-0.4 mg/dl; P=0.06), but did in the iodine group (from 2.0+/-0.4 to 2.3+/-0.5 mg/dl; P=0.001). No patient had CIN in the gadolinium group whereas 5 (23%) patients had this phenomenon in the iodine group (P=0.048). Contrast regimen was very well tolerated in the gadolinium group, with only transient headache in two patients. Gadodiamide mixed with a small quantity of iohexol is safe in patients with azotemia undergoing diagnostic coronary angiography. The image qualities obtained with this combination are also satisfactory in all of the cases. Further evaluation of the safety of this technique is warranted, especially in other types of diagnostic and interventional procedures in which a higher amount of contrast dye is needed.