What is the latest literature on contrast-induced nephropathy (CIN), also known as contrast-induced acute kidney injury (CI-AKI)?

From the Guidelines

Contrast-induced nephropathy (CIN) prevention should prioritize adequate hydration and minimization of contrast media volume, as recommended by the 2021 ACC/AHA/SCAI guideline 1. The most effective approach involves identifying high-risk patients (those with pre-existing kidney disease, diabetes, advanced age, or dehydration) and implementing preventive measures.

• Key prevention strategies include:
  • Intravenous hydration with isotonic saline
  • Minimizing contrast volume using the lowest diagnostic dose possible
  • Using iso-osmolar or low-osmolar contrast agents preferred over high-osmolar agents
  • High-dose statins before diagnostic catheterization have been demonstrated to reduce the occurrence of contrast-induced AKI 1 Recent studies suggest that the risk of CIN may be lower than previously thought, especially with newer contrast agents, but vigilance remains important in high-risk populations.
• Post-procedure monitoring of kidney function at 48-72 hours is recommended for at-risk patients. The pathophysiology involves direct tubular toxicity and renal vasoconstriction leading to medullary hypoxia and oxidative stress, explaining why adequate hydration is so important for prevention. Other measures such as the use of radial access instead of femoral access have been shown to significantly reduce the risk of AKI compared with femoral access 1. N-acetylcysteine has fallen out of favor due to inconsistent evidence 1. The use of low-osmolar or iso-osmolar contrast media is recommended, and the volume of contrast media should be minimized 1. Short-term, high-dose statin therapy should be considered, and iso-osmolar contrast media should be considered over low-osmolar contrast media 1. Furosemide with matched hydration may be considered over standard hydration in patients at very high risk for CIN or in cases where prophylactic hydration before the procedure cannot be accomplished 1. Prophylactic renal replacement therapy is not recommended as a preventive measure 1.

From the Research

Definition and Incidence of Contrast-Induced Nephropathy

• Contrast-induced nephropathy (CIN) is a complication of contrast medium administration during diagnostic and interventional procedures, with important prognostic relevance 2.
• The incidence of CIN varies depending on the population and the definition used, with some studies reporting an incidence of less than 3% in patients with normal baseline renal function, while others report an incidence of up to 50% in patients with chronic kidney disease (CKD) 3.

Risk Factors for Contrast-Induced Nephropathy

• Chronic kidney disease is the primary predisposing factor for CIN, with patients having an estimated glomerular filtration rate <60 ml/1.73 m2 being at high risk 4.
• Other risk factors for CIN include hydration status, the type and amount of contrast used, use of concomitant nephrotoxic agents, and recent contrast administration 4.
• The Mehran scoring system can be used to risk stratify patients undergoing contrast exposure 3.

Prevention of Contrast-Induced Nephropathy

• The cornerstone of CIN prevention is adequate parenteral volume repletion, with intravenous hydration with isotonic saline being the standard of care for prophylaxis 5.
• Other strategies for preventing CIN include withholding potentially nephrotoxic medications, using low or iso-osmolar contrast agents, and minimizing contrast volume 4.
• N-acetylcysteine may be considered for prevention of CIN in high-risk groups, although its effectiveness is still debated 6.
• Hemofiltration has been shown to be an effective strategy for CIN prevention in patients with CKD undergoing cardiovascular procedures, particularly when performed before and after contrast exposure 2.

Controversies and Debates

• Recent studies have suggested that the risk of CIN may be overestimated, with some studies reporting a lower incidence of CIN than previously thought 3.
• The definition and diagnosis of CIN are still debated, with different studies using different criteria to define CIN 3.
• Further studies are needed to determine the true incidence and risk factors for CIN, as well as the most effective strategies for prevention 3.