Contrast-Induced Nephropathy (CIN): An Update from the Cardiology Literature

Happy new year to all! I’ve been thinking about how much Nephrology content there is in non-renal journals and how much we miss by just reading the usual renal periodicals each month. You cannot be expected to read every Cardiology/Endocrinology/Rheumatology journal every month so I thought I would bring you what I’ve noticed in the non-Nephrology literature recently. Today I’m focusing on CIN. If the post proves popular, we may run a regular literature watch from non-Nephrology journals on RFN.

Since, N-acetylcysteine (NAC) has fallen out of favor, all we have in our armamentarium for CIN prevention is IV volume expansion. There were 3 recent publications in the Journal of the American College of Cardiology which you may have missed regarding novel therapies for CIN prevention. Firstly, the PRATO-ACS study which was a RCT of rosuvastatin in >500 consecutive statin-naïve patients presenting with a NSTEMI who proceed to cardiac catheterization. Greater then 50% of patients were diabetic and mean eGFR was 82mls/min. The incidence of CIN was significantly lower in the rosuvastatin group (6.7 vs 15.1%) as were other renal, cardiac events and mortality. In the same issue, a study of 3000 diabetic CKD (Stage 2 or 3) patients randomized patients to either rosuvastatin or placebo 5 days before intra-arterial contrast. The rosuvastatin group had a significantly lower incidence of CIN compared to controls (2.3% vs 3.9%). Statins are postulated to improve CIN by their anti-inflammatory and positive endothelial effects. These large scale prospective RCTs support a meta-analysis from 2012 suggesting a benefit in statin use for CIN.

A meta-analysis of trials using ascorbic acid for the prevention of CIN was also recently published in J Am Coll Card. Over 1500 patient were included from 9 RCTs and it was demonstrated that receiving ascorbic acid (mix of oral and IV) had 33% less risk of CIN compared to the control group. Six of the 9 studies had significantly p values themselves. The postulated mechaism of action of ascorbic acid is similar to the theory behind NAC, antioxidant free-radical scavenger i.e who knows?

Verdict: The 2 statin trials are good sized prospective studies in high risk populations (ACS & diabetic CKD) receiving intra-arterial contrast and do support short term statins in this circumstance. Knowledge gaps exist for lower risk patients and those already on statins (a lot of patients these days) as well as dose, duration and the benfit of other statins. The Vitamin C meta-analysis looks interesting but given the study heterogeneity and the NAC story, I remain skeptical until well powered RCTs are performed.