Comparison of cardiovascular and renal toxicity after cardiac catheterization using a nonionic versus ionic radiographic contrast agent

Both ionic and nonionic contrast agents used in angiography are relatively well tolerated but have a number of undesirable effects, particularly on the cardiovascular system and the kidney.^1-7 Whereas low osmolar agents may reduce acute events, contrast nephropathy remains a common cause of in-hospital renal injury, and the potential advantage of one contrast agent over another is less well defined.^2,3 The best method of evaluating the relative toxicity of iopamidol and diatrizoate is by a randomized controlled clinical trial. In principle, there are 2 major designs for a randomized trial: (1) a cohort trial that compares results between different patients, and (2) a crossover trial that compares results within the same patient. The crossover design provides the greatest assurance that between-patient differences will not affect the results, and this design is generally well suited for investigations of pharmaceuticals. As part of a randomized trial using a cohort design,^1,2 we prospectively designed a crossover protocol so that any patient randomized in the trial would receive the alternative contrast agent if a second coronary angiogram proved to be clinically indicated within the study period. In all, 67 of the 443 randomized patients had a second procedure, 41 of whom received the alternative agent. This report summarizes the results of 41 randomized patients in this prospective controlled crossover investigation.