Changing trends in incidence and predictors of radiographic contrast nephropathy after percutaneous coronary intervention with use of fenoldopam

Nephrotoxic effects in high-risk patients undergoing angiography

BACKGROUND

The use of iodinated contrast medium can result in nephropathy. Whether iso-osmolar contrast medium is less nephrotoxic than low-osmolar contrast medium in high-risk patients is uncertain.

METHODS

We conducted a randomized, double-blind, prospective, multicenter study comparing the nephrotoxic effects of an iso-osmolar, dimeric, nonionic contrast medium, iodixanol, with those of a low-osmolar, nonionic, monomeric contrast medium, iohexol. The study involved 129 patients with diabetes with serum creatinine concentrations of 1.5 to 3.5 mg per deciliter who underwent coronary or aortofemoral angiography. The primary end point was the peak increase from base line in the creatinine concentration during the three days after angiography. Other end points were an increase in the creatinine concentration of 0.5 mg per deciliter or more, an increase of 1.0 mg per deciliter or more, and a change in the creatinine concentration from day 0 to day 7.

RESULTS

The creatinine concentration increased significantly less in patients who received iodixanol. From day 0 to day 3, the mean peak increase in creatinine was 0.13 mg per deciliter in the iodixanol group and 0.55 mg per deciliter in the iohexol group (P=0.001; the increase with iodixanol minus the increase with iohexol, -0.42 mg per deciliter [95 percent confidence interval, -0.73 to -0.22]). Two of the 64 patients in the iodixanol group (3 percent) had an increase in the creatinine concentration of 0.5 mg per deciliter or more, as compared with 17 of the 65 patients in the iohexol group (26 percent) (P=0.002; odds ratio for such an increase in the iodixanol group, 0.09 [95 percent confidence interval, 0.02 to 0.41]). No patient receiving iodixanol had an increase of 1.0 mg per deciliter or more, but 10 patients in the iohexol group (15 percent) did. The mean change in the creatinine concentration from day 0 to day 7 was 0.07 mg per deciliter in the iodixanol group and 0.24 mg per deciliter in the iohexol group (P=0.003; value in the iodixanol group minus the value in the iohexol group, -0.17 mg per deciliter [95 percent confidence interval, -0.34 to -0.07]).

CONCLUSIONS

Nephropathy induced by contrast medium may be less likely to develop in high-risk patients when iodixanol is used rather than a low-osmolar, nonionic contrast medium.

Contrast-associated nephropathy

Contrast-associated nephropathy (CaN) has become a major cause of iatrogenic acute renal failure, especially with the increasing use of radiographic contrast media in both diagnostic and interventional procedures. CaN is the third most common cause of iatrogenic acute renal failure, and is associated with increased morbidity and in-hospital mortality. CaN typically presents as an acute rise in serum creatinine levels, usually within 48 hours after exposure to contrast media. Renal medullary ischemia secondary to contrast-induced vasoconstriction is now believed to be the most likely cause of CaN, although direct renal tubular cytotoxicity does appear to play a role. The occurrence of CaN is directly related to the number of coexisting clinical risk factors. Among the many risk factors, preexisting renal impairment, the presence of diabetes mellitus and the volume of the contrast agent administered are the most important. The most effective means of reducing the incidence of CaN is through prevention, by first identifying the risk factors and then attempting to correct for them before the administration of contrast material. Although the earliest and most well-tested preventive measure, namely intravenous hydration, continues to be the most effective way to prevent CaN, recent studies have provided many new preventive modalities. The growing use of these new agents, such as acetylcysteine, endothelin blockers, and most recently fenoldopam, has increased the options available for the prevention of CaN.

Strategies for Treatment and Prevention of Acute Renal Failure

Acute renal failure (ARF) is a potentially life-threatening medical condition that often complicates the hospitalization of critically ill patients. A variety of therapeutic strategies has been studied for both preventing ischemic and nephrotoxic injury to the kidney and improving renal function in established ARF. This article summarizes the role of pharmacologic therapy in the treatment of ARF. Strategies to reduce extracellular fluid volume and preserve renal function with loop diuretics, low-dose dopamine, and renal replacement therapy will be discussed. The value of preventative therapy has increased, and identifying patients at high risk for development of ARF is critical. Modification of drug regimens, administration of less nephrotoxic medications, and volume expansion prior to nephrotoxin administration can minimize toxicity to the kidney. The search for new agents that can improve survival, decrease the need for renal replacement therapy, and hasten the recovery of renal function in ARF is ongoing.