Is treatment with N-acetylcysteine to prevent contrast-induced nephropathy when using bicarbonate hydration out of date?

Chronic renal failure (CRF) is a major risk factor for contrast-induced nephropathy (CIN) and could be prevented by bicarbonate hydration. The effect of N-acetylcysteine (NAC) in preventing CIN in patients treated by bicarbonate hydration has never been investigated.Patients admitted for cardiac angiography from January 2002 to November 2004, with stable CRF (glomerular filtration rate (GFR) < 56 ml/min, Cockcroft-Gault formula) were included in a prospective, randomized, double-blind study comparing the efficacy of oral NAC + bicarbonate hydration vs oral placebo + bicarbonate hydration to prevent CIN. NAC 1,200 mg twice daily or placebo was given on Day -1 and Day 0 (Day 0 = cardiac angiography). A 1.4% bicarbonate solution (1 ml/ kg/h) was administered 12 hours before and after cardiac angiography. The overall CIN incidence on Day 2 was defined by one or more of the following criteria: increase in serum creatinine > 44.2 micromol/l, increase in serum creatinine > 25% or decrease in GFR > 5 ml/ min.Between NAC group (n = 28) and placebo group (n = 32) there was no difference in baseline demographics (age, sex ratio, weight, arterial hypertension, diabetes), in Day 0 characteristics (serum creatinine, GFR, hematocrit, protidemia) and in Day 0 cardiac angiography procedure (diagnostic or interventional, number of stents, type and volume of contrast media infused). The overall incidence of CIN in the NAC and placebo groups was 7.1 vs 9.3% (p = 1), respectively, and the rates of the observed criteria a, b, and c were 0 vs 6.3% (p = 0.49), 3.5 vs 6.3% (p = 1), and 7.1 vs 9.3% (p = 1).In CRF patients undergoing cardiac angiography, the use of bicarbonate hydration is associated with a very low incidence of CIN. In these conditions, on the basis of our results, we cannot draw any meaningful conclusion on the effect of NAC on the prevention of CIN.