Nephrotoxicity of nonionic contrast media after cardiac angiography

Determinants of amount of contrast utilized in patients undergoing percutaneous coronary procedures

OBJECTIVE

To determine predictors of contrast amount during coronary angiography and percutaneous coronary intervention.

BACKGROUND

Contrast-induced nephropathy is a leading cause of hospital-acquired acute renal insufficiency. During percutaneous coronary procedures, contrast amount is a major risk factor incriminated in development of contrast-induced nephropathy.

METHODS

Demographic and procedural details were obtained for consecutive patients undergoing percutaneous coronary procedures between January 2002 and October 2005 (N=962, mean+/-standard error of contrast amount: 216.6+/-3.0 ml) at a tertiary care hospital.

RESULTS

A significant difference (P value <0.05) in unadjusted mean contrast volume was observed between subgroups of percutaneous coronary intervention vs. coronary angiography, patients with a history of coronary artery bypass grafting, patients undergoing additional procedures and multivessel and multisite percutaneous coronary interventions. On General Linear Model analysis, independent predictors (beta coefficient, 95% confidence interval, P value) of increased contrast amount during percutaneous coronary procedures were history of coronary artery bypass grafting (44.4, 30.6-58.2, <0.001), type of coronary procedure (85.2, 73.4-97.0, <0.001 for percutaneous coronary intervention vs. coronary angiography), number of interventions and number of additional procedures performed. Among additional procedures, rotablation, intravascular ultrasound and Angiojet were associated with increased contrast use. No significant independent effect on the contrast amount was observed with percutaneous coronary intervention location (right coronary artery vs. left anterior descending artery vs. circumflex artery) site (ostial vs. proximal vs. mid vs. distal) of percutaneous coronary intervention or with interventions on chronic total occlusions on the contrast amount.

CONCLUSION

Data from our study could guide the coronary angiographer in moderating the volume of contrast utilized as well as assist with the elective planning of complex therapeutic procedures.

Efficacy of N-acetylcysteine and hydration versus placebo and hydration in decreasing contrast-induced renal dysfunction in patients undergoing coronary angiography with or without concomitant percutaneous coronary intervention

OBJECTIVE

Contrast-induced renal dysfunction is an iatrogenic complication that occurs more frequently in patients with preexisting renal dysfunction. A prospective, double-blind, randomized, placebo, controlled trial was completed to assess the efficacy of N-acetylcysteine in decreasing the incidence of contrast-induced renal dysfunction in patients with an acute coronary syndrome and renal insufficiency who underwent coronary angiography with or without percutaneous coronary intervention.

METHODS

With similar intravenous hydration protocols, 20 patients received N-acetylcysteine (treatment group) and 20 patients received placebo (control group) in a twice per day dosing regimen with one dose before and three doses after contrast media exposure.

RESULTS

The two groups were similar at baseline on demographic and clinical characteristics, and preexisting renal insufficiency. Contrast-induced renal dysfunction, defined as an increase in serum creatinine greater than 44 micromol/L (.5 mg/dL) and/or 25% above baseline within 48 hours, occurred in 7.5% of the cohort, with 2.5% in the treatment group, and 5% in the control group, for an absolute difference of 2.5%. There was no difference in serum creatinine or creatinine clearance at 24 hours or at 48 hours between the treatment and control groups.

CONCLUSION

These results suggest that this cohort gained no added protection to renal function with the use of N-acetylcysteine.

Contrast medium use

Various properties of iodinated contrast media (osmolality, ionic versus nonionic, and viscosity) may contribute to contrast-induced nephropathy (CIN). Therefore, the choice of contrast medium affects the risk for CIN. There is good evidence that low-osmolar contrast media are less nephrotoxic than high-osmolar contrast media in patients at increased risk for CIN who receive intra-arterial iodinated contrast. Current evidence suggests that nonionic isosmolar contrast presents the lowest risk for CIN in patients with chronic kidney disease (CKD), particularly in those patients with diabetes mellitus. Intra-arterial administration of contrast media may be associated with a greater risk for CIN above that observed with intravenous administration. The use of gadolinium or CO(2) as alternative contrast media to avoid the risk of nephrotoxicity cannot be substantiated by clinical trials and therefore cannot be recommended. Most studies show that, within a class, higher volumes (>100 mL) of iodinated contrast medium are associated with a higher risk for CIN. However, in patients at high risk, such as those with CKD and diabetes, even small volumes of contrast medium can have adverse effects on renal function.

Contrast medium-induced nephrotoxicity: pathophysiology and prevention

Contrast medium-induced nephrotoxicity (CMN) is a common form of iatrogenic acute renal failure. Typically, patients experience changes in serum creatinine or creatinine clearance between 1 and 5 days after exposure to a contrast medium, but they rarely require dialysis. The mechanism for CMN is not understood, but renal insufficiency, dehydration, and congestive heart failure are risk factors. The frequency of CMN with high-osmolality versus low-osmolality media is controversial. Prophylaxis can reduce CMN. Of many different strategies, hydration with normal saline before and after exposure offers the best protection with the fewest adverse effects.

Comparative toxic effects of iobitridol and iohexol on the kidney

RATIONALE AND OBJECTIVES

The authors compare the toxic effects of iobitridol and iohexol, which are nonionic contrast media with equivalent osmolalities and viscosities on the kidney.

METHODS

In a rat acute renal failure (ARF) model, iobitridol or iohexol (both at the dose of 2.87 g I/kg) were injected to rats after pretreatment with indomethacin and N omega-nitro-L-arginin methyl ester. The effects on histopathology, creatinine clearance, and urinary N-acethyl-beta-D-glucosaminidase (NAG) activity were assessed. In a rat renal slice system, the slices were exposed to iobitridol or iohexol (both at the concentration range of 17.5-70 mg iodine/mL) for 60 min. The accumulation of para-aminohippuric acid (PAH), an organic anion, and the intracellular potassium content as the indicators of renal tubular injury were measured to assess the direct effects of iobitridol and iohexol on renal tubules.

RESULTS

In the ARF model, no significant difference was detected between the effects of iobitridol and those of iohexol on the creatinine clearance and urinary NAG activity 24 hours after the injection. However, iobitridol produced a lower degree and incidence of renal tubular injury of renal proximal tubules (P < 0.001) and distal tubules (P < 0.05) compared with iohexol. In the rat renal slice system, the iobitridol treatment had significantly less effect on the PAH accumulation compared with iohexol (P < 0.001). There were no changes in the intracellular potassium content.

CONCLUSIONS

These findings suggest that iobitridol has significantly less toxic effects on the kidney compared with iohexol under the condition of our experiment.

Protection from the nephrotoxicity of contrast dye

Previous studies have reported a 4%-50% incidence of acute renal failure (ARF) following the use of radiocontrast media in patients with preexisting chronic renal insufficiency. In these studies, ARF was defined as a rise of the serum creatinine of at least 1 mg/dl above baseline. Using the same criteria, we studied 214 patients undergoing various intravascular radiocontrast media procedures. Patients were infused with a specially prepared cocktail solution (NSMF) containing 1000 ml half-normal saline, 12.5 g of mannitol (M), I ampule NaHCO3, and 200 mg of furosemide (F) at 100 ml/h from one hour prior to two hours after the procedure. Urinary output was replaced with normal saline for at least 6 h after the procedure. Seven percent of the patients developed acute renal insufficiency. Only 3% of the patients had a rise in serum creatinine greater than 2 mg/dl. No patient required dialysis therapy after the procedure. There was one unrelated death caused by acute myocardial infarction postangioplasty. Risk factors for development of ARF despite cocktail administration included the presence of diabetes mellitus and angiotensin converting enzyme (ACE) inhibitor therapy. We concluded that the properly administered NSMF solution protects against radiocontrast dye induced renal failure. In select patients with chronic renal insufficiency, consideration should be given to withholding ACE inhibitor therapy for 24-48 h prior to administration of intravenous radiocontrast dye. A large controlled trial will be required to establish whether the NSMF solution offers benefit beyond that of saline hydration alone.

Comparison of a low osmolarity nonionic radiographic contrast agent with a standard medium on renal function in cyanotic and normal dogs

Renal dysfunction may follow administration of iodinated radiographic contrast agents. This complication may be less common when low osmolarity nonionic agents are used. Although potential benefits from the use of low osmolarity nonionic contrast may be minimal in individuals with normal physiology, a greater benefit has been postulated in the presence of chronic cyanosis. To test this hypothesis, six adult mongrel dogs underwent anastomosis of the inferior vena cava to the left atrium. This produced chronic cyanosis with a mean pO2 of 48 +/- 4 mm Hg and polycythemia with a mean hematocrit of 56 +/- 2 gm%. Three to 5 months after preparation, these cyanotic dogs and five control dogs each received diatrizoate (a high osmolarity ionic agent) or ioversol (a low osmolarity nonionic agent), 465 mg iodine/kg body weight, by intravenous bolus injection. One month later, each animal received the other agent. The order of administration was randomized. Renal function studies, including serum creatinine and creatinine clearance, were performed precontrast, after 60 min, and 24 hr postcontrast. Neither agent adversely affected renal function in either the cyanotic or the normal group. We conclude that at the doses that are commonly used in clinical practice, high osmolarity ionic contrast agents do not create a greater risk of renal injury than do low osmolarity nonionic agents in this model of cyanosis.

Nephrotoxicity of contrast media following cardiac angiography: pathogenesis, clinical course, and preventive measures, including the role of low-osmolality contrast media

OBJECTIVE

To review the incidence, definition, clinical course, risk factors, pathogenesis and prevention of contrast-associated nephropathy (CAN) following cardiac angiography with emphasis on differences between high-osmolality contrast media (HOCM) and low-osmolality contrast media (LOCM).

DATA SOURCES

Investigations in animal models and in patients following cardiac angiography.

DATA EXTRACTION

Animal models of the pathogenesis of CAN are presented. Human studies describing the incidence, clinical course, risk factors, and prevention of CAN are reviewed. Comparative clinical trials of HOCM (diatrizoate, metrizoate) and LOCM (iohexol, iopamidol, ioxaglate) nephrotoxicity following cardiac angiography are critically evaluated.

DATA SYNTHESIS

All clinical studies comparing CAN of HOCM versus LOCM following cardiac angiography have some methodologic limitations (e.g., small sample size, lack of control for other factors) that may affect renal function, lack of stratification for other reported risk factors, and variable or short follow-up periods.

CONCLUSIONS

Whether the incidence of CAN following cardiac angiography is reduced with LOCM remains controversial. The incidence of CAN in patients with normal renal function does not appear to differ in patients treated with LOCM versus HOCM because few patients in each group develop renal failure. Additional controlled clinical trials comparing CAN of LOCM and HOCM in patients with renal dysfunction are needed. Because of greater product cost and scarcity of documented benefit compared with HOCM, selection of LOCM based on the presence of renal dysfunction cannot be recommended at this time.

Contrast agents for cardiac catheterization: conceptions and misconceptions

Ionic and nonionic contrast materials are similarly efficacious in providing excellent images with minimal risk to the patient. In comparison with ionic media, the nonionic agents produce minor alterations in intracardiac and peripheral pressures as well as in electrocardiographic intervals and morphology. In addition, nonionic media are less often associated with undesirable symptoms, such as flushing and vomiting. At the same time, ionic and nonionic media are accompanied by a similar incidence of nephrotoxicity, serious arrhythmias, and death. Finally, nonionic contrast material is substantially more expensive than ionic media. In light of this marked difference in cost, one could argue that nonionic media should be reserved for "high-risk" patients, that is, those with a history of a serious adverse reaction to ionic contrast media and those in whom contrast-induced hypotension would be particularly deleterious.

A randomized comparison of the nephrotoxicity of iopamidol and diatrizoate in high risk patients undergoing cardiac angiography

Three hundred seven high risk patients with renal impairment (serum creatinine greater than or equal to 1.5 mg/dl) were randomized in a double-blind manner to either iopamidol (a nonionic, low osmolar radiocontrast agent) or diatrizoate (a conventional radiocontrast agent) at cardiac angiography with subsequent follow-up study of renal function. Baseline clinical and angiographic variables were similar in the iopamidol (n = 155) and diatrizoate (n = 152) groups. Change in renal function after angiography was less pronounced with iopamidol compared with diatrizoate as measured by mean ( +/- SD) increase in 24 h serum creatinine (0.11 +/- 0.2 versus 0.22 +/- 0.26 mg/dl, p less than 0.001), mean maximal increase in serum creatinine (0.2 +/- 0.44 versus 0.38 +/- 0.73 mg/dl, p less than 0.0001) and percent of patients with a maximal increase in serum creatinine greater than 0.5 mg/dl (8% versus 19%, p less than 0.01). Such differences could not be documented in diabetic patients using insulin. There was no significant difference between agents in the number of patients developing clinically severe acute renal dysfunction. It is concluded that iopamidol is less nephrotoxic than diatrizoate in high risk patients at cardiac angiography. However, the difference in nephrotoxicity is small, of no major clinical significance in the majority of high risk patients and could not be documented in insulin-using diabetic patients. Iopamidol may be the preferred agent in certain patients with advanced renal impairment, but further study is warranted.

High-dose contrast agent administration during complex coronary angioplasty

To examine the necessity and consequences of high-dose contrast media administration during coronary angioplasty, the records of 730 consecutive patients over a 6-month period were reviewed. The 54 patients (7%) requiring contrast agent doses greater than or equal to 400 ml were examined in detail. The mean contrast dose in this group was 496 +/- 76 ml (range 400 to 785 ml). Their mean age was 63 +/- 11 years (range 36 to 83 years), 10 patients had diabetes mellitus (19%), and four patients had a baseline creatinine level greater than or equal to 1.5 mg/dl (7%). Following coronary angioplasty, the serum creatinine rose from 1.1 +/- 0.2 to 1.2 +/- 0.3 (p = 0.08). The creatinine rose greater than or equal to 0.5 mg/dl in six patients (11%) and greater than or equal to 1.0 mg/dl in one patient (2%). Five of these six patients had either diabetes mellitus, baseline renal insufficiency, or both. Oliguria was not observed. The most important procedural factors contributing to the high doses of contrast media were multilesion and multivessel angioplasty in 96% and 83% of patients, respectively, prior bypass surgery in 52%, and combined diagnostic cardiac catheterization and angioplasty in 13%. Thus renal dysfunction following high-dose contrast agent administration during complex coronary angioplasty is infrequently associated with nephrotoxicity. Whenever possible, contrast doses in patients with diabetes mellitus and renal insufficiency should be minimized.