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ICON: 1-year mortality lower with ionic vs. nonionic contrast medium during cardiac catheterization
In patients with chronic kidney disease undergoing cardiac catheterization, the use of an ionic low-osmolar contrast medium appears to yield numerically lower mortality compared with use of a nonionic contrast medium, according to 1-year results of the ICON trial.
In the randomized, prospective, controlled, double blind, multicenter study, researchers evaluated 146 high-risk patients with stable chronic kidney disease undergoing arterial catheterization. Stable chronic kidney disease was defined as two consecutive stable serum creatinine values of more than 1.5 mg/dL and at least 3 mg/dL. Patients were randomly assigned to receive the low-osmolar contrast medium ioxaglate (Hexabrix, Guerbet; n = 74) or the nonionic iso-osmolar contrast medium iodixanol (Visipaque, GE Healthcare; n = 72).
The primary endpoint was median peak increase in serum creatinine between days 0 and 3. The primary objective was analysis of differences in mortality, MI and coronary revascularization (PCI or CABG) at 1 year. Patients were followed by telephone at 30 days and 1 year.
At 30 days, there was one death in the ioxaglate group (1.4%) vs. four in the iodixanol group (5.7%; RR = 0.24; 95% CI, 0.03-2.06). Acute renal failure occurred in 18 patients in the ioxaglate group vs. 14 patients in the iodixanol group (24.3% vs. 20%; RR = 1.22; 95% CI, 0.66-2.25). Dialysis was required in three patients in the ioxaglate group vs. one patient in the iodixanol group (4.1% vs. 1.4%; RR = 2.84; 95% CI, 0.3-26.64).
At 1 year, the researchers found a numerically lower rate of all-cause mortality in the ioxaglate group vs. the iodixanol group (4.1% vs. 13.6%; RR = 0.3; 95% CI, 0.09-1.07). Deaths in the ioxaglate group were caused by the following: MI (n = 1), cardiac arrest (n = 1) and unknown cause (n = 1). In the iodixanol group, deaths were caused by HF (n = 4), acute renal failure (n = 1), MI (n = 1), cardiac arrest (n = 1) and idiopathic pulmonary fibrosis (n = 1). The researchers observed no significant between-group differences in MI (1.4% vs. 1.5%; RR = 0.9; 95% CI, 0.06-14.17) and repeat revascularization (6.8% vs. 9.1%; RR = 0.75; 95% CI, 0.24-2.35).
“In high-risk patients undergoing coronary angiographic procedures, there were no significant differences in 1-year mortality between the ionic [low-osmolar contrast medium] ioxaglate and the nonionic [iso-osmolar contrast medium] iodixanol,” the researchers wrote. “Given that the ICON study was underpowered to test differences in mortality at 1 year, the present results must be considered hypothesis-generating and have to be confirmed in appositely designed clinical trials.” – by Jennifer Byrne
Disclosure: Two researchers have participated on advisory boards of AstraZeneca, OrthoMcNeil and Regado Biosciences, and report receiving institutional research support from Bristol-Myers Squibb/Sanofi Aventis and The Medicines Company.
Perspective
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This study adds long-term outcomes data to the very important clinical question of the outcome differences driven by chemical composition of radiocontrast media. Patients with chronic kidney disease are increasingly seen in the interventional laboratory, and represent a very high-risk subset from an outcome standpoint. The study is well-conducted and the authors deserve credit for their attention to this patient subset. Although statistically not significant, the strong numeric difference is certainly hypothesis-generating, and indicates the necessity of retesting this hypothesis with a larger study sample. Results of several other strategies, such as access-site choice or contrast-conserving technologies, to improve outcomes of patients with chronic kidney disease after radiocontrast exposure will also enhance our understanding of the dynamics driving outcomes in this space.